Contents
Preface
1. Scope
2. Terms and Definitions
3. Stamping direction
3.1. Establish the rotation of the part
3.2. Determine the orientation of the part
4. Deep drawing process
4.1. The use of drawing process standards
4.2. Deep drawing depth of parts
4.3. Corner radius
4.4. Elongation of materials
4.5. Deepen the transition angle
4.6. Draw the bevel deeply
4.7. Internal forming angles
4.8. Planar fillets
4.9. Open and deep
4.10. Stiffeners
5. Flanging process
5.1. Flange holes
5.2. Flange type
5.3. Single negative angle flange
5.4. Secondary flanging
5.5. Angle of the flange
5.6. Flanging direction
5.7. Radii of flanged corners
5.8. Straight flange height
5.9. Compression/stretch flanging
5.10. The distance between flips
5.11. Flange to edge distance
5.12. Flange to punching distance
6. Trimming process
6.1. Type of dicing
6.2. Typical dicing
6.3. Complex dicing
6.4. Angle of the punching surface
6.5. Punching and cutting vertical wall angle
6.6. The distance from the cut edge to the vertical wall
6.7. The distance from the edge line to the edge line
6.8. Undulating cut edges
6.9. Lapping of cut edges
6.10. Compression/Extension Gaps
6.11. Cutting corners
6.12. Scrap angles
7. Punching process
7.1. Punching type
7.2. Standard typical hole type
7.3. Holes on three or more faces
7.4. Complex holes
7.5. Tumbling/reaming (single process)
7.6. Stamping nuts
7.7. Corner radius of the hole
7.8. Punching angle
7.9. The distance from the hole to the wall
7.10. The distance from the hole to the edge line
7.11. Relationship between holes and holes
7.12. Minimum punching size
8. Pipe bending process
8.1. Common methods of bending pipes
8.2. Pipe bending deformation and minimum bending radius
Preface
The purpose of compiling this document is to provide guidance on stamping process for designers of sheet metal products, in the initial stage of product design, consider whether the parts are easy to manufacture, whether it is conducive to product quality control, the stamping process of good product digital modules released to the next link, to avoid subsequent product changes caused by unreasonable stamping process, improve development efficiency, reduce mold costs, improve production efficiency, but also conducive to reducing the uncontrollable factors of the late stamping mold development cycle, Laying the foundation for the early production of qualified stamping parts.
Stamping process specifications
1 Range
This document stipulates the general guidelines for the structural design of stamping parts, as well as the reasonable structural size and limit size of various sheet metal characteristics, through the analysis and induction of the whole process of stamping parts, under the premise of not affecting the function of product use, there is an overall grasp of the stamping process of parts, and try to avoid the appearance of unmanufacturable, uneconomical and uncontrollable quality sheet metal structures, providing convenience for the manufacture and production of parts.
This document applies to the structural design of sheet metal parts involving body-in-white parts and the design of cold stamped parts in other systems in the development of our models.
2 Terms and Definitions
2.1
Stamping direction
The vector direction relative to the car coordinates of the part when the mold is stamped.
2.2
Unloading
Cut the raw material into the required geometry.
2.3
Blanking
Separate the sheets to obtain the flat blank or part of the desired shape and size.
2.4
Punching
The scrap is separated along the closed contour and the perforated part is obtained.
2.5
Cut the edges
Cut off excess edge material from the formed part.
2.6
curved
Changing the angle of the part along a bending line, when using this term as the name of the operation, specifically refers to the bending line is the bending of a straight line.
2.7
Drawing
The sheet produces plastic deformation under tensile stress and its thickness is basically unchanged.
2.8
figuration
The plate is locally plastically deformed, and the part is directly copied according to the shape of the punch and concave molds.
2.9
plastic
Correct the part to an accurate shape and size.
2.1
Flip holes
Punching the edge of a vertical hole on a pre-made or unformed sheet is a special case of flanging.
2.11
Flanging
The curved line along the curve changes the angle of the edge of the workpiece.
2.12
amputation
Separate the part from the blank or the part from the part along an unclosed profile.
2.13
incision
At the edge of the part, the scrap is separated along an unclosed contour.
2.14
Cut the tongue
Cut and bend part of the sheet along the unclosed profile.
2.15
Roll round
Bending the ends or edges of the material into a near-closed cylinder is a special case of bending.
2.16
Hemming
Bend the ends of the material into overlapping edges or other geometric shapes.
2.17
Swelling
Plastic deformation of sheets or hollow blanks under the action of two-way tension stress.
2.18
Shrink
Reduces the radial size of the end of the hollow core blank or tubular blank.
2.19
Shrinkage
Reduces the radial size of the middle of a hollow or tubular blank.
2.2
Embossing
The sheet is deformed in the direction of thickness, causing its surface to form patterns or characters.
2.21
Flare
Expands the radial size of the ends of hollow or tubular blanks.
2.22
renovation
A layer of material is cut along the outer edge or inner hole of the semi-finished part to improve the dimensional accuracy of the part and the finish of the punched cross-section.
2.23
Leveling
Eliminates warping, local convexity and unequal defects in plates or flat parts.
2.24
alignment
Restores the profile or tube to a straight state.
2.25
Press-fit
The flanges of the two parts are joined by means of folding edges.
Benefit collection: a full set of 500G information, click on the small editor's avatar private message I reply to the "information" two words, automatic collection!
3 Stamping direction
The most critical factor in the stamping process analysis of sheet metal parts is the direction of stamping of the part, which must be determined first before the analysis. The stamping direction consists of two factors: the rotation of the part and the orientation of the part.
The rotation of a part is the position of the part in the mold after it is rotated.
The part orientation is the downward side of the part. All molds or operations for a part should use the same orientation.
For the purpose of stamping process evaluation, the determination of the stamping direction is divided into two steps, and it is assumed that there are only three basic stamping processes: deep drawing, flanging, cutting edge and punching. The determination of the stamping direction only considers the shape of the part itself, not the process.
3.1. Establish the rotation of the part
If the part is symmetrical to the left and right relative to the midline of the body, the part cannot be rotated left and right, only forward and backward. Confirm that the part can be left and right common mode, and if so, determine the middle connection area (also considering the part ordering), in which case the part can only rotate in the direction of the connection area.
3.1.1. Deep drawing process
Suppose the part is placed on a plane (with flanging removed);
Flip forward and backward, left and right to balance the angle of the vertical wall at both ends;
If it is a progressive mold, you should ask the mold engineer how to sort it.
3.1.2. Flanging process
Adjust the rotation angle of the part so that most of the flanges of the part can be directly formed;
If the press block of the mold is subjected to a lateral force, rotate the part to eliminate the lateral force so that the press block is in equilibrium.
3.1.3. Cutting edges and punching processes
If the part has the following punching types:
Flange holes, nut holes, pierced holes, countersunk nut holes, bosses, in consultation with the product engineer, determine whether the punching can be canceled; if not, rotate the part so that the punching direction is vertical.
If there are more than two types of punching, the flange hole determines the rotation position of the part. (If it is a continuous progressive punching die, it should be consulted with the mold engineer)
Rotate the part so that the punching direction is vertical, which is the rotation position of the part.
If the part does not have punching characteristics, analyze the angle of the peripheral edge surface of the part so that the edge direction is vertically downward. This is the rotation position of the part.
3.2. Determine the orientation of the part
The orientation of the part (part facing down) is mainly composed of the following 3.2. 1) ~5) characteristics determine that all operations of the part use the same direction.
1) If the part has an inward flange, the part is oriented in the same direction as the first bend (Figure 3-1).
2) If the part has a hole or cut part on the flange, negotiate with the product engineer whether the hole or cut part can be canceled. If not, the part orientation should be opposite to the direction in which the part protrudes to avoid scrap falling into the part cavity (Figure 3-2).
Figure 3-1
Figure 3-2
3) If the part has the following punching types: flange hole, nut hole, punch hole, countersunk nut hole, boss. Consult with the product engineer to decide whether to cancel the punching. If not, the part orientation will be determined by the flanging of the hole or nut hole. If there are multiple punch types, the flange hole is used to determine the part orientation.
4) If the cut edge surface of the part has an angle, the direction of the part should be within ±30° of the angle between the cut edge face and the horizontal direction.
5) If there is no one of the above, there is no need to analyze the part orientation.
4. Drawing process
The drawing process includes all processes that require edge rings to control the flow of the sheet, as well as an elongation drawing forming process.
4.1. Use of drawing process standards
z Parts with more than twice the thickness of the material are dented or raised deformations, or are open and deep, using this standard.
z Parts that require a crimping ring to control material flow are used in this standard.
z If there are no above two cases, enter the flanging process analysis. If in doubt, please consult a mold engineer.
Note to mold engineers: For a forming process (without crimping rings), if there is no concave or convex deformation between the flanges on both sides, skip this section to enter the flanging process analysis.
4.2. Deep drawing depth of the part
Feature Definition: The deep drawing depth of the part is the maximum depth of the part in the direction of the mold stamping. Flanging is not taken into account, because the flange is flattened to the deep surface when it is pulled deep, and it is bent later.
Calculate the maximum blanking value of the part, the width value is based on the maximum width of the part plus 2XD (part drawing depth) plus 125mm, and the length is based on the maximum length of the part plus 2XD (part drawing depth) plus 125mm.
The calculation of the maximum depth and blanking value is to ensure that the drawing depth of the part does not exceed the machining capacity of the machine tool in terms of depth, length and width.
Figure 4-1
Stamping direction
4.3. Corner Radius
Feature definition: The corner radius is the bending radius formed by the intersection of two part faces, which is not suitable for flanging, open parts and style molding. Only the inner surface radius is evaluated. The first purpose here is to target the formability of the part, and then consider the manufacture and repair of the mold.
Note: Use as large a rounded corner as possible under the part design permission.
Figure 4-2
Table 4-1 Deep corner radius
| R | Pull deep rounded corners halfway through |
| ≥6.0mm | The smallest standard, as large as possible |
| 5.0mm-6.0mm | Deviation from standards (increased mold costs) |
| The following flanged rounds are excluded: ●Open pieces with edges and rounded corners ● Design style feature line |
4.4. Elongation of materials
Feature Definition: This feature refers only to the formed portion within the deep vertical wall or the formed portion that extends to the edge of the part. Elongation refers to the percentage of the original sheet that is lengthened by drawing deeper. The purpose of this standard is to consider the molding properties of the part to ensure successful molding.
Figure 4-3
Table 4-2 Elongation of materials
| Maximum elongation of material (t=0.60~3.00mm, steel plate) | |
| ≤15% | standard |
| 15-25% | Difficult (increased mold cost) |
| ＞25% | You need to change the design |
4.5. Deepen the transition angle
Feature Definition: Design the vertical wall of the part as much as possible to ease (feature A) to avoid clipping situations when the depth changes (see A in Figure 4-4), and minimize the corresponding vertical wall heights (B in Figure 4-4) to avoid increasing the steps of the deep punch, otherwise increasing the cutting size and cost.
Figure 4-4
Table 4-3 Deep transition angles
| Part parts | Standard value | Exceeded the standard | |
| A、C | Surface change angle Vertical wall change angle | Steel ≤ 30° | Angle greater than standard value (increase mold cost) |
| B | Contralateral height difference angle | Steel ± 15° |
4.6. Drawing deep draft bevel
Feature definition: The drawing drawing angle refers to the angle between the vertical wall and the drawing depth direction of the part, and the angle of the part is less than 6°, which will reduce the molding performance and increase the transportation and inventory costs. Angles less than 0° will form a dead angle of molding.
Figure 4-5
Table 4-4 Drawing depth draft bevels
| A | Draw the bevel deeply |
| ≥6° | Complies with standards |
| 0° to 6° | Increase mold costs (Design changes are recommended) |
| ≤0° (deep negative angle) | By increasing the mold (or station), it is possible to increase the wedge. (It is highly recommended to change the design, unless the product has special requirements) |
*For girder parts, 3° to 6° increases the mold cost, and below 3° requires a design change.
4.7. Internal forming angles
Feature definition: Internal forming angle A refers to the angle between the vertical wall of the mold and the direction of drawing depth. This feature does not refer to deep vertical walls. This standard takes into account part formability.
Figure 4-6
Table 4-5 Internal Molding Angles
| A | Internal molding angle |
| ≥30° | standard |
| 6°～30° | Non-standard (increase mold cost) |
| 0°～6° | It is recommended to change the design |
| ≤0° | Change the design |
*Width-to-depth ratio of internal forming in all directions: W:H≥1.2.
4.8. Planar fillets
Feature definition: The plane fillet R is the smallest internal fillet formed in the direction of stamping. This standard does not apply to exposed fillets and deep vertical wall fillets, and considers part formability.
Note: Design flat fillets as large as possible.
Figure 4-7
Table 4-6 Flat fillets
| Flat fillet R | |
| R≥ 1XD, meanwhile, R≥ 6.0mm | In the actual design, the larger the fillet, the better |
| Below standard | Increase mold costs |
| Note: This standard is established on the premise that the conditions for the radius of the fillet and the internal forming angle must be met. |
4.9. Open and deep
Feature Definition: If a part has a relatively consistent cross-sectional shape, such as a hat type, the following design points should be considered. This allows the mold to be designed to be open and deep, fully saving costs and sheet size.
1) Design relatively consistent cross-sectional shapes as much as possible.
2) Try not to be closed at both ends.
3) Parts change as slowly as possible in depth design.
4) As little as possible to form a 90° shape change on the cross-section.
Figure 4-8
4.10. Stiffeners
Feature Definition:
1) In order to improve the strength of long sheet metal parts, they should be designed to be reinforced. The shape, size and appropriate spacing of the ribs are shown in Table 4-7: The shape, size and appropriate spacing of the ribs in Table 4-7
| Semicircular tendons | Size | h | B | r | R1 | R2 | |
| Minimum allowed | 2t | 7t | t | 3t | 5t | ||
| So so | 3t | 10t | 2t | 4t | 6t | ||
| Trapezoidal ribs | | Size | h | B | r | r1 | R2 |
| Minimum allowed | 2t | 20t | t | 4t | 24t | ||
| So so | 3t | 30t | 2t | 5t | 32t | ||
| Suitable distance between reinforcement ribs and between reinforcement ribs and edges | L≥3B K≥(3~5)t |
2) Bending at the bending corner of the bent part can play a role in strengthening the ribs. The shape, size and spacing of the reinforcement ribs at the corners are shown in Table 4-8.
The shape, size and spacing of the reinforcement ribs at the corners of Table 4-8
| L | R1 | R2 | R3 | H | B | Rib spacing |
| 12 | 6 | 9 | 5 | 3 | 16 | 60 |
| 15 | 7 | 12 | 6 | 4 | 20 | 70 |
5. Flanging process
Flanging features include all sheets with an outflip and an internal flange and flange with a spacing of greater than 60mm between the front and back and left and right. Internal flanges with pitches less than or equal to 60 mm will be discussed as punching in the punching process standard.
5.1. Flange holes
Feature Definition: A flange hole is an internal opening greater than 60mm in any direction, and there is a circle of flanges around the hole. Usually this purpose is to increase the strength of the structure (A in Figure 5-1). In Figures 5-1B and C, there are no strict holes, flange heights, and angles are variable.
Figure 5-1
5.2. Flange Type
Feature definition: The following 7 flanged forms may appear on the periphery of the part, but inside the part, there can only be A, B, C forms. D, E, F, G, etc. in the part inside the flanging form design needs to be confirmed by the mold engineer, another purpose of this diagram is to assist the product engineer to choose the best flanging form.
DD = stamping direction
Figure 5-2
5.3. Single negative angle flange
Feature definition: When the flanging direction is negatively angled to the stamping direction, it is necessary to form a diagonal wedge, and in the lower die, a wedge or rotating mechanism is required to remove the part, and there can be no secondary flanging here. This standard is intended to guarantee the strength of the lower wedge or rotating mechanism.
Figure 5-3
Table 5-1 Negative angle flange angle
| A | Negative angle flange angle inside |
| ≥60° | Complies with standards |
| 60°—45° | Exceeding standards (increasing tooling costs) |
| ＜45° | Requires a design change |
5.4. Secondary flanging
Feature definition: According to the stamping direction, after a flange and then folded inwards, a secondary flange is formed. This requires flanging molding with a wedge, and a wedge or rotating mechanism in the lower die in order to remove the part. The standards for H, L, B and C are designed to guarantee the strength of the downswing or rotating mechanism. The standard A is to not have a wedge shape.
Figure 5-4
Table 5-2 Secondary flanging criteria
| Feature dimensions | standard | Exceeded the standard |
| H | ≥13mm | < 13mm or < 1.5L (change design) |
| A | ≥5°—Inner plate case ≥10° - outer panel | <5° increase mold cost (requires diagonal wedge shaping) |
| B | ≥5° | Change the design <5° |
| C | ≥93° | Change the design < 93° |
5.5. Flange angles
Feature definition: The angle of the flange is the angle between one edge and the direction of the punch when the flange has angles in the front view direction, assuming that one edge is horizontal and the other edge is angled to the stamping direction. The purpose of this standard is to prevent wrinkles or material build-up.
Figure 5-5
Benefit collection: a full set of 500G information, click on the small editor's avatar private message I reply to the "information" two words, automatic collection!
Table 5-3 Flange angles
| A | Flange angle |
| ≥45° | Complies with standards |
| 20°—45° | Exceeded standard values (increased tooling costs) |
| 0°—20° | Additional molds (or stations) and/or wedges are required (Design changes are recommended) |
| <0° (negative angle) | It is highly recommended to change the design |
5.6. Flanging Direction
Feature definition: The flanging direction is determined by the relative relationship between the first stage flanging and the stamping direction, and the purpose of this standard is to prevent the use of a bi-directional pressing core on the mold. Figure A standard can also punch holes on the mold at the same time.
Figure 5-6
Table 5-4 flanging direction
| Figure A flanges coincide with the stamping direction | Standard - First Choice (simultaneous punching on the die) |
| Figure B Flanging is opposite to the direction of stamping | Standard - Second choice (punching on the mold cannot be made at the same time) |
| Figure C has flanges above and below | Unreasonable - increase the cost of the mold using two-way pressing core, in the mold can not be punched at the same time |
5.7. Radii of flanges
Feature description: The radii of a rake is the radius of the fillet (or minimum fillet) within the flange. If it is less than the standard, it will cause the flanging strength to decrease, and if it is larger than the standard, it will produce excessive springback.
Figure 5-7
Table 5-5 Flanged corner radius
| R | Radii of flanged corners |
| 1.5Xt | Standard value |
| <1.5Xt | Deviation from standards (increased mold costs) |
| 1.5Xt～5t | Deviation from standards (increased mold costs) |
| >5t | Requires a design change |
| Note 1: Round the calculated radii of the flange round to 0.5mm. Note 2: This standard does not apply to hemming and tumbling. Note 3: For 60mm or less than 60mm, refer to the punching standard. |
5.8. Straight flange height
Feature description: The straight flange height refers to the distance from the flanged rounded tangent to the fringe. If it is less than standard, the flange will be deformed or twisted.
Figure 5-8
Table 5-6 flange height
| F | Flange height |
| ≥3.0mm | Complies with standards |
| ＜3.0mm | Exceeded standard values (increased tooling costs) |
| Note 1: This standard is not suitable for the hole turning process; Note 2: Please refer to the hemming standard before the hemming. |
5.9. Compression/stretch flanging
Characteristic description: Compression/stretch flanging exists at all non-straight flanges. Determine the maximum height of the stretch flange, the steel plate flange fillet divided by 3, aluminum can be flanged line rounded by 8. The maximum height of the compressed flange, as per table. If the flange falls under the following three cases, it is necessary to analyze its formability by a computer.
1) The flange is located on the plane and undulating surface.
2) The radii of the radii of the flange do not meet the criteria for the radii of the flange.
3) Flange angle A is less than 80° or greater than 100°.
Figure 5-9
Table 5-7 compression flanging
5.10. Turn over the distance between
Characteristic description: The distance from flanging to flanging refers to the distance between relative flanges with the same stamping direction in any of the following three cases. This standard is to guarantee a flange press block of sufficient strength and a flange insert of sufficient strength.
Figure 5-10
Table 5-8 Flange spacing
| FF Flange distance | ≥55.0mm | Complies with standards |
| 25.0mm—55.0mm | Exceeded standard values (increased tooling costs) | |
| 13.0mm—25.0mm | Exceed the standard value, increase the mold or station, It may be necessary to increase the gas spring pressure material | |
| ＜13.0mm | Change the design | |
| L Flange length | ≤D/1.5 | Complies with standards |
| >D/1.5 | Exceeded standard values (increased tooling costs) |
5.11. The distance from the flange to the edge line
Characteristic description: The distance from flange to tangent refers to the distance from the flanged round tangent to the corresponding tangent line. This feature is suitable for flanges and flanges. This standard guarantees that there are enough flanging press surfaces to avoid twisting and deformation when flanging.
Figure 5-11
Table 5-9 Flange to Edge Distance
| D | The distance from the flange to the tangent edge |
| ≥25mm | Complies with standards |
| 13mm——25mm | Exceeded standard values (increased tooling costs) |
| ＜13mm | Change the design |
5.12. Flange to punching distance
Feature description: The distance from flanging to punching refers to the distance from the punching edge to the nearest flanged fillet tangent. This standard simply refers to the punching process before the flanging process. It is to prevent distortion of the hole shape when flanging.
Figure 5-12
Table 5-10 The distance from the flange to the punch
| D | The distance from the flange to the punch |
| ≥3.0mm或3Xt | Complies with standards |
| <3.0mm或3Xt | Change the design |
| Note: If the punching is performed at the same time as or after the flanging, please refer to the punching process standard. |
6. Trimming process
Cut edge features include peripheral trim edges and internal holes with each directional spacing greater than 60 mm for all sheets. Internal holes with a spacing of less than or equal to 60 mm will be discussed as punching holes in the punching process standard.
6.1. Type of Dication
Characteristic description: Cuts greater than 60 mm in each direction of the opening inside the sheet. There are 2 types of cuts in this category; typical types can be completed in one punch, and complex types require 2 punches and cuts. See 2 examples below. This criterion is used to distinguish and evaluate the type of chunks.
Figure 6-1
Table 6-1 Block types
| Diced type | |||
| Face angle | Punch angle A | ≤15°(UP OR DOWN) | Standard - In the stamping direction can be punched and cut completed |
| Typical dicing | Punch angle B | ≤30°(UP OR DOWN) | Standard - a single punch cut (station) can be completed |
| Complex dicing | ＞30°(UP OR DOWN) | It can be completed by requiring more than 2 punching and cutting (station). |
6.2. Typical dicing
Characteristic description: A typical cut is a cut that occurs on one or more planes, and the angle of the upper corner (UP) and the lower foot (DOWN) of all punching faces is within 30 °.
Note: This definition is intended to punch the insert sufficiently to lay out the screws and pins.
Figure 6-2
Note: Check irregularly shaped cuts and try to choose the smallest standard close to the above shape.
Table 6-2 Minimum Cut Block Criteria
| Minimum dicing standard | ||
| Circle diameter D | square In | Ellipse or rectangle In L |
| ＞65mm | ＞60mm | >40mm >100mm |
| Note: Cutting blocks that are less than the conditions in the table will be more difficult to punch and increase the mold cost. When the diagonal size of the cut block is greater than 450mm, the stamping die needs to be added. |
6.3. Complex dicing
Characteristic description: Complex cutting blocks are irregular cuts that are punched and cut on 2 or more planes, and require 2 processes to complete, because the angle between 1 or more cutting blocks and the horizontal surface of the mold (see sketch below) exceeds 30°. Its purpose is to provide a stable incision quality. This standard is used for cuts that are greater than 60 mm in any direction (less than 60 mm are treated according to punching).
Figure 6-3
Table 6-3 Complex incisions
| Complex incisions | standard | irrationality |
| Cut shape | Cannot be circular | rotundity Requires a design change |
| The cut edge offset distance | ≥ 1.0mm 2 sides | ＜1.0mm Strongly request a design change |
| The intersection angle of the edge lines | Sharp corners 2 sides | The intersection angle of the edge line is not a sharp angle that requires changing the design |
6.4. Angle of the punching surface
Characteristic description: The angle of the punching surface refers to the angle between the plane where the punching line is located and the horizontal plane (plane) of the mold. 0° is the best angle of the punching surface. This standard guarantees that, provided that the lowest grade cutting edge material is used, there is no need for additional maintenance of the edge at the lower end punching surface and no product defects at the upper punching surface.
Figure 6-4
Table 6-4 Punching surface angle
| A | Punching surface angle | |
| ≤20° (upper or lower) ≤15° (upper or lower) | t≤1.5mm t＞1.5mm | standard |
| > standard — 30° (upper or lower end) | Difficult (increased mold cost) | |
| >30° (upper or lower) | More difficult, may require wedges and increased mold (increase station) |
6.5. Angle of the punched vertical wall
Characteristic description: The angle of the punched vertical wall refers to the angle between the plane where the punching and cutting line is located and the mold guide. Punching vertical walls is usually also called shear vertical walls, because its cutting principle is the same as the shearing principle. The purpose of this standard is to guarantee the desired trimming quality at the punching wall.
Figure 6-5
Table 6-5 Punch cutting vertical wall angle
| t Sheet thickness | A | Punch the vertical wall angle |
| ＜1.5mm | ≥10° | standard |
| 1.5—1.9mm | ≥15° | |
| ≥1.9mm | ≥20° | |
| N/A | Less than the above criteria | It is necessary to pull out a gentler vertical wall to cut when drawing deeper. And shape the mold to its proper shape on the mold later, or add a mold or wedge to complete the blanking of the section (contact the mold engineer to discuss whether there is another way) |
6.6. The distance from the cut edge to the vertical wall
Feature description: The distance from the edge line to the vertical wall refers to the distance between the internal or external punching line and the surface where the punching line is located and the adjacent punching wall theoretical intersection. Punching horizontal distance F refers to the distance from the punching tangent line to the tangent line of the arc and the face. This criterion is to ensure sufficient strength of the withdrawal block (when the face where the edge line is located under the adjacent punching wall) and a sufficient strength of the lower die-cut edge insert (when the edge line is located on the surface above the adjacent punching wall).
Figure 6-6
Table 6-6 Distance from the cut edge to the vertical wall
6.7. The distance from the edge line to the edge line
Characteristic description: The distance from the edge line to the edge line, including the outer edge line and the inner edge line, is composed of the following combinations: the distance from the EE outer edge line to the outer edge line. The distance from the CE's internal cutout line to the outer cut edge line. The distance from the CC internal cutout line to the internal cut line. This standard is for both the upper return plate and the lower mold insert to have sufficient strength.
Figure 6-7
Table 6-7 Distance from the edge line to the edge line
| EE THAT | ≥55mm | standard |
| 25mm to 55mm | Increase mold costs | |
| 8mm to 25mm | Add punching die | |
| ＜8mm | The design needs to be changed | |
| CC | ≥55mm | standard |
| 8mm to 55mm | Add punching die | |
| ＜8mm | The design needs to be changed | |
| Cut the ears EE＜55mm | EE≥D | standard |
| EE<D | The design needs to be changed |
6.8. Undulating cut edges
Characteristic description: Undulating cut edges are generally in the place where the edge line and the flange line intersect, and there are two forms as follows: the class A design is to directly cut the entire edge, and the class B design provides a concave cut. The purpose of this standard is to eliminate cracks that occur at the intersection due to excessive deeping. Aluminum is more sensitive to cuts than steel and requires a larger cut radius, as shown in the figure below.
Figure 6-8
Table 6-8 undulating cut edge standards
| Undulating categories | D (undulating cut edge distance) | R (edge radius) | |
| standard | ≥1.0mm | steel | aluminium |
| ≥6.0mm | ≥9.0mm | ||
| Exceeded the standard (Increase mold cost) | ＜1.0mm | 3.0 TO 6.0mm | 6.0 TO 9.0mm |
| Exceeded the standard (Increase mold cost) | N/A | ＜3.0mm | ＜6.0mm |
6.9. Lapping of cut edges
Characteristic description: It is used to complete the same edge cutting edge with 2 sets of molds to avoid the lapping of 2 sets of molds, and generally exists on the surface of the cutting edge at a variable angle. (Lap notch is generally not considered when designing a product)
Figure 6-9
6.10. Compression/Extension Gaps
Feature description: Compression/extension notches are generally arranged in curved or cornered flanges. Its role is to prevent flanging wrinkles and flanging cracking. The criterion is to ensure the machinability of the punched insert (the size of radius R) and the discharge of notched waste (the size of angle A).
Figure 6-10
Table 6-9 Compression/Extension Gap Criteria
| Notch category | A (opening angle) | R (cut edge fillet) | Compression/extension notch (flange straight height) |
| standard | ≥10° | ≥6.0mm | Reference flanging process characteristics (Article 8) |
| Exceeded the standard | ＜10° Strongly request a design change | ＜6.0mm Increase mold costs |
6.11. Cutting Angles
Feature description: In the case of external and internal blanking, no matter how small the angle between the edge lines is, as long as it is between 60 ° and 179 °, the corner fillet radius R is the minimum of 6mm. When the angle is less than 60°, the radius of the corner is determined according to the following table standard. The main purpose is to ensure that the upper and lower die punching inserts have sufficient strength when the punching angle is greater than 60 °. At less than 60°, it is possible to avoid adding local inserts to the upper molded core and the lower die punching inserts, resulting in increased costs. Another purpose is to improve the machinability of the upper and lower die punching inserts.
Figure 6-11
Table 6-10 Cutting angles
| Trim edge angle A | 60°-179° | 40°-60° | 30°-40° | 20°-30° | 10°-20° | ＜10° |
| Standard radius R | ≥6.0mm | ≥8.0mm | ≥14.0mm | ≥18.0mm | ≥21.0mm | ≥24.0mm |
| The first level exceeds the standard Increase mold costs | N/A | 6mm— 8mm | 6mm— 14mm | 6mm— 18mm | 6mm— 21mm | 6mm— 24mm |
| The second level exceeds the standard | < change the design at 6.0mm | |||||
| This standard does not apply in the case of undulating cut edges and flange notches In the case of 2 corners in a complex punching block (consult with the mold engineer) |
6.12. Scrap angles
Characteristic description: Scrap corner refers to the angle between any two sides of the edge line in the outer cut edge line, excluding the internal cut block and punch. This standard is to ensure the smooth discharge of blanking waste and to avoid the addition of special structures in the mold.
Figure 6-12
Table 6-11 Scrap angle standard
| A | Scrap angles |
| ≥10° | standard |
| 0°——10° Parallel angles | Increase mold costs |
| ＜0° Limited angles | Add molds and consider changing the design |
7. Punching process
Punching features include all internal holes with a front-to-back, left-right spacing of less than or equal to 60mm. Internal holes with a spacing greater than 60 mm will be discussed as edge-cutting features in the Edge Process Standard.
7.1. Punch types
Feature Definition: The punching type is those that are less than 60mm (diagonal measurement). It can be the 9 types shown below. These standards are used to identify and reduce the types of holes that require special punching equipment.
| Table 7-1 Stamping Types |
Figure 7-1
7.2. Standard typical hole type
Feature Definition: Typical holes are those of size/shape on 1 or 2 planes whose angle to datum ≤ 20°. This standard is to minimize investment in punching equipment.
Figure 7-2
Table 7-2 Standard typical hole type
| Typical hole shape | standard |
| Atypical irregular holes | Non-standard - not recommended hole shape |
| The analysis of the hole type should be after the analysis of the punch type |
7.3. Holes on three or more faces
Feature definition: A hole in 3 or more planes, through 2 or more prisms on the plane, the angle of the punched surface to the datum ≤ 20°, and the angle from the punched bevel surface A to the datum surface cannot be greater than 70°, this standard provides this type of manufacturable hole standard.
Note: The hole shape cannot be round.
Figure 7-3
Table 7-3 Maximum angle of punching in the elevation angle and top-down direction
| A elevation angle | Pa top-down direction punching maximum angle |
| ＞70° | Exceed the standard, change the design |
| 60°——70° | 69°——111° |
| 50°——60° | 67°——113° |
| 45°——50° | 64°——116° |
| 40°——45° | 61°——119° |
| 35°——40° | 58°——122° |
| 30°——35° | 53°——127° |
| 25°——30° | 36°——144° |
| 20°——25° | 36°——144° |
| ＜20° | Unlimited |
| Angles beyond this standard require the addition of a mold (or station) and/or wedge |
Table 7-4H, F, TT standards
| H vertical wall height | ≤ 10mm standard |
| > 10mm exceeded the standard | |
| F plane length | ≥ 5mm standard |
| < 5mm exceeded the standard | |
| TT tangent to tangent | ≥0mm standard |
| <0mm exceeded the standard | |
| Exceeding the standard, increasing the cost of the mold |
7.4. Complex Holes
Feature Definition: Complex holes are those atypical holes on 2 or more surfaces where the angle of any part of the surface of these punches to the plane exceeds 20°. The purpose of these standards is to provide a complex hole of qualified quality, the size E in the figure refers to the standard 8mm (distance from hole to wall), this part is suitable for the case where the punching cut is less than or equal to 60mm in any direction.
Figure 7-4
Table 7-5 Standards for complex holes
| Complex incisions | standard | deviation |
| Cut shape, S | Can't be round | Round, requires a change in design |
| Cut offset distance, D | Both sides ≥ 1.0mm | ≤ 1.0mm, requires a design change |
| Cut cross angle, C | On both sides are sharp corners | Not sharp corners, requiring a design change |
7.5. Turning/Reaming (Single Process)
Feature Definition: The flange/reaming has continuous edges around the perimeter of the hole, and the material thickness at the flange is less than or equal to the thickness of the part plate. Punching and hemming are done in one process. The first of the reference flanging standards (flanging holes) with a flanging cut of more than 60 mm. These standards provide a quality repeating process in which these types of holes must be punched and formed on the surface of the part at 90° in the direction of stamping.
Figure 7-5
Table 7-6 Edged holes/elliptical holes
| Flanged/elliptical holes | ||
| Feature dimensions | Standards | Deviation – Requires a change in the design |
| L flange length | ≤ minimum size Hole/slot ÷ 6 times the plate thickness T Hole/slot ÷ 12 times the thickness of the aluminum plate T | > minimum size Hole/groove ÷ 6 plate thickness T Hole/slot ÷ 12 sheet thickness T |
| F-folded edges face straight to the length | ≥ 1/2 × t minimum (all holes) sheet steel ≥ 1 × t minimum (all holes) aluminum plate ≤2 × t minimum (standard well) | < 1/2 × t steel plate < 1 × t aluminum plate or >2 × t (standard holes only) |
| R edge radius | 11/2 × t (metal thickness) steel plate 2 × t aluminum plate | Does not meet the standard requirements |
| Note: The closer all sizes are to 0.5mm, the better. |
7.6. Stamping nuts
Feature Definition: A stamping nut is a feature of the exterior of a metal sheet. Under the action of the original pressure, the nut is punched on the steel plate through the nut head and pressed onto the sheet. The following stamping nut design standard diagram is set according to the fastening requirements.
Figure 7-6
表7-7CHART#1-STANDARD
7.7. Corner radius of the hole
Feature Definition: All angle A between 60° and 120° the corners of the inner and outer holes require a radius of 0.5mm. When angle A exceeds 180°, the inner hole corner becomes the outer hole corner. Holes are prone to cracking without a radius at corners, and are characterized by the reduction of punch damage and part breakage.
Figure 7-7
Table 7-8 Hole Corner Radii
| Hole corner radius R | |||
| All steel plates (t<1.5mm) and all aluminum inner plates (t< 1.5mm ﹞ | All steel plates (t≥1.5mm) and all aluminum internal plates (t≥ 1.5mm) | All aluminium exterior panels | Select the result |
| 0.5mm radius | 1.0mm radius | 0.3mm radius | standard |
| ≥ a radius of 0.5mm | ≥ 1.0mm radius | ≥ a radius of 0.3mm | Deviation (increased mold cost) does not apply to irregular holes |
| ≤ a radius of 0.5mm | ≤ 1.0mm radius | ≤ a radius of 0.3mm | Request to change the design (all holes) |
| Note: This standard does not apply to holes and sharp corners on complex holes |
7.8. Punching angles
Feature definition: Punch angle refers to the angle between the centerline of the hole and the direction of stamping. The size and accuracy of the hole remains relevant to the centerline of the hole. The centerline of the hole is perpendicular to the plane on which the hole is located, and is not necessarily consistent with the direction of stamping. The purpose of this feature is to prevent breakage of the punch, avoid the use of special punches or avoid adding molds or wedges.
Figure 7-8-1
Table 7-9 Punching angles
| The maximum punching angle A is guaranteed to have the minimum amount of punch damage | |||
| Hole size | Metal thickness, t | The standard value is maximum punch angle A | deviation |
| ≤5.0mm | ≤2.3 | 15 | Add a die or wedge |
| ＞2.3 | 10 | ||
| ≥5.0mm 到 10.0mm | ＜1.5 | 20 | |
| 1.5～3.0 | 15 | ||
| ＜3.0 | 10 | ||
| ≥10.0mm | ＜1.5 | 30 | |
| 1.5～3.0 | 20 | ||
| ＞3.0 | 10 | ||
| Squeeze or fold the edges | N/A | ||
| Countersink holes | 7 | ||
| Note 1: The punching angle (in degrees) of any hole exceeds the size of the hole (in mm) or 15 degrees, but within the limits of the table above, the approval of the mold engineer is required. Note 2: Deviations are allowed only for roundness of the hole. |
Figure 7-8-2
Figure 7-8-3
7.9. The distance from the hole to the wall
Feature definition: Hole-to-wall refers to the distance D from the boundary of the punch or the punch rod (whichever is closest) to the nearest theoretical intersection of the wall and the punching plane. The surface of the part around the entire hole edge should be flat, and the minimum distance to the hole F is 3mm, which is aimed at maintaining the rejecting rubber (size D) and providing a usable hole (size F).
Figure 7-9
Table 7-10 Distance from hole to wall
| D - The distance from the centerline of the hole to the wall | ||||||
| Punch bar part size The size of the hole | 13mm ≤13mm | 16mm 13.0mm ~16.0mm | 20mm 1.6mm~20.0m m | 25mm 20.0mm~25.0 mm | 32mm 25.0~32.0mm | 40mm 32.0~60.0 mm |
| The minimum standard value | ≥19.5 | ≥21 | ≥23.0 | ≥25.5 | ≥29 | ≥33 |
| Error - Increases the cost of the die | 12.5~19.5 | 14~21 | 16~23 | 18.5~25.5 | 22~29 | 26~33 |
| Strong demand for design changes | ＜12.5 | ＜14 | ＜16 | ＜18.5 | ＜22 | ＜26 |
| F - The width of the plane around the hole | ||||||
| The minimum standard value | ≥3 | ≥3 | ≥3 | ≥3 | ≥3 | ≥3 |
| Error - Increases the cost of the die | ＜3 | ＜3 | ＜3 | ＜3 | ＜3 | ＜3 |
7.10. The distance from the hole to the edge line
Feature Definition: The distance from a hole to a cutting edge is the distance from the edge of the punch or the punch rod part (whichever is closest) to the nearest inner/outer cutting edge. The purpose of this feature is to be able to use all standard punching dies and to avoid having to use lower die inserts and to guarantee the quality of the holes.
Figure 7-10
Table 7-11 Distance from the hole to the tangent edge
| D1 - In the case of the cut edge and punch on the same die, the distance from the centerline of the hole to the edge | ||||||
| Punch bar part size The size of the hole | 13mm ≤13mm | 16mm 13.0mm～ 16.0mm | 20mm 1.6mm～ 20.0mm | 25mm 20.0mm～ 25.0mm | 32mm 25.0～ 32.0mm | 40mm 32.0～ 60.0mm |
| The minimum standard value | ≥25.5 | ≥27 | ≥29 | ≥31.5 | ≥35 | ≥39 |
| Non-standard 1-increase Add stamping die fee use | 14.5～25.5 | 16～27 | 18～29 | 20.5～31.5 | 24～35 | 28～39 |
| Non-standard 2-to-be Ask to increase the punch model | ＜14.5 | ＜16 | ＜18 | ＜20.5 | ＜24 | ＜28 |
| D2 - In the case of cutting edges and punching on different dies, the distance from the edge of the hole to the cutting edge | ||||||
| The minimum standard value | ≥4mm | |||||
| Requires a design change | ＜4mm |
7.11. Relationship between holes and holes
Feature Definition: The hole-to-hole relationship includes the distance between two punches or between the two punch rods (whichever is closest), and when punching holes are separated, as long as D3<4mm can be considered non-standard (discussed with die engineers). Non-standard values may require non-standard punching equipment and/or removal of the return rubber.
Figure 7-11
Table 7-12 Relationship between holes and holes
| D1 - The distance between the punch rods | D2-The distance from the center of the hole to the center of the hole | D3 - Hole-to-hole distance when punching holes apart |
| ≥25mm (min. standard) | Minimum standard values (see Table A on the next page) | D3≥4mm is the minimum standard value |
| 1.5mm~25mm is non-standard (increase the cost of the die) | Non-standard 1 (increased die cost) (see Table A on the next page) | D3<4mm requires a design change |
| <1.5mm is non-standard (add die) | Non-standard 2 (increased die cost) (see Table A on the next page) |
The values in Table 7-13 are measured from the center of the hole to the center of the hole to illustrate the distance between the standard punch rods in the punching operation. Distance (D2) - Center of hole to center of hole (green is the standard value, blue is the non-standard one, red is the non-standard two)
Table 7-13 Measurements from the center of the well to the center of the hole
| The punch rod is within inches Hole size | 13mm ≤13mm | 16mm 13~16mm | 20mm 16~20mm | 25mm 20~25mm | 32mm 25~32mm | 40mm 32~60mm |
| 13mm amount 13mm | ≥38.0 | ≥39.5 | ≥41.5 | ≥44.0 | ≥47.5 | ≥51.5 |
| 14.5～38.0 | 16.5～39.5 | 28.0～41.5 | 20.5～44.0 | 24.0～47.5 | 28.0～51.5 | |
| ＜14.5 | ＜16.0 | ＜18.0 | ＜20.5 | ＜24.0 | ＜28.0 | |
| 16mm 13.0 ～ 16.0mm | ≥39.5 | ≥41.0 | ≥43.0 | ≥45.5 | ≥49.0 | ≥53.0 |
| 16.0～39.5 | 17.5～41.0 | 19.5～43.0 | 22.0～45.5 | 25.5～49.0 | 29.5～53.0 | |
| ＜16.0 | ＜17.5 | ＜19.5 | ＜22.0 | ＜25.5 | ＜29.5 | |
| 20mm 16.0 ～ 20.0mm | ≥41.5 | ≥43.0 | ≥45.0 | ≥47.5 | ≥51.0 | ≥55.0 |
| 18.0～41.5 | 19.5～43.0 | 21.5～45.0 | 24.0～47.5 | 27.5～51.0 | 31.5~55.0 | |
| ＜18.0 | ＜19.5 | ＜21.5 | ＜24.0 | ＜27.5 | ＜31.5 | |
| 25mm 20.0 ～ 25.0mm | ≥44.0 | ≥45.5 | ≥47.5 | ≥50.0 | ≥53.5 | ≥57.5 |
| 20.5～44.0 | 22.0～45.5 | 24.0～47.5 | 26.5～50.0 | 30.0～53.5 | 34.0～57.5 | |
| ＜20.5 | ＜22.0 | ＜24.0 | ＜26.5 | ＜30.0 | ＜34.0 | |
| 32mm 25.0 ～ 32.0mm | ≥47.5 | ≥49.0 | ≥51.0 | ≥53.5 | ≥57.0 | ≥61.0 |
| 24.0～47.5 | 25.5～49.0 | 27.5～51.0 | 30.0～53.5 | 33.5～57.0 | 37.5～61.0 | |
| ＜24.0 | ＜25.5 | ＜27.5 | ＜30.0 | ＜33.5 | ＜37.5 | |
| 40mm 32.0 ～ 60.0mm | ≥51.5 | ≥53.0 | ≥55.0 | ≥57.5 | ≥61.0 | ≥65.0 |
| 28.0～51.5 | 29.5～53.0 | 31.5～55.0 | 34.0～57.5 | 37.5～61.0 | 41.5～65.5 | |
| ＜28.0 | ＜29.5 | ＜31.5 | ＜34.0 | ＜37.5 | ＜41.5 |
Note: All holes must have a minimum distance of 4mm around their edges to reduce the possibility of deformation of the holes due to punching operations.
Table 7-14 In the case of cutting edges and punching on different dies, the distance from the edge of the hole to the edge
| D3 In the case of cutting edges and punching holes on different dies, the distance from the edge of the hole to the cutting edge | |
| The minimum standard value | ≥4mm |
| Requires a design change | ＜4mm |
7.12. Minimum Punching Size
Characteristic definition: When punching, due to the limitation of the punch strength, the size of the hole should not be too small, and its value is related to the shape of the hole, the mechanical property thickness, etc.
Table 7-15 Minimum punching sizes
| type | Free punch punching | Precision guided punching | ||
| rotundity | rectangle | rotundity | rectangle | |
| The size of the hole | D≥2t | l≥1.5t | D≥1t | l≥0.8t |
Note: t - material thickness (mm)
8. Pipe bending process
8.1. Common methods of bending pipes
Pipe bending process is with the rise of automobiles, motorcycles, bicycles, petrochemicals and other industries and developed, pipe bending Commonly used methods can be divided into bending, push bending, bending and rolling; according to bending heating or not can be divided into cold bending and hot bending; according to bending, there is no filler (or mandrel) and can be divided into core bending pipe and coreless bending pipe.
Fig. 8-1, Fig. 8-2, Fig. 8-3 and Fig. 8-4 are respectively the mold diagram of the bending, pushing, bending and rolling device:
Fig. 8—1 There is a core elbow on the pipe bending machine
1- Briquette, 2- Mandrel, 3- Clamping Block, 4- Bending Die Tire, 5- Anti-Wrinkle Block, 6- Tube Blank
Fig. 8-2 mode cold push bending device
1—Pressure column, 2—Guide sleeve, 3—Tube blank, 4—Bending mold
Fig. 8—3V-shaped pipe fitting bending die
1-Punch die, 2-Tube blank, 3-Swing die
Fig. 8—4 Principle of three-roller bending pipe
1 axis, 2, 4, 6 - roller wheel, 3 - active shaft, 5 - steel pipe
It is related to the mechanical properties of materials, the structural size of pipe fittings, bending processing methods and other factors.
Fig. 8-5 Pipe bending force and its stress strain
a stress state, b stress strain state
The minimum bending radius of different bending processing methods is shown in Table 8-1.
Table 8—1 Minimum bending radius when a pipe is bent
(Unit: mm)
| Bending method | Minimum bend radius |
| Bending | (3~5) D |
| Round the corner | (2~2.5) D |
| Roll bends | 6D |
| Push bends | (2.5~3) D |
Note: D is the outer diameter of the pipe.
Steel and aluminum tubes have a minimum bending radius as shown in Table 8-2.
Table 8—2 Minimum bending half of steel pipe and aluminum pipe
(Unit: mm)
| Pipe outer diameter | 4 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 |
| Minimum bend radius | 8 | 12 | 16 | 20 | 28 | 32 | 40 | 45 | 50 | 56 |
| Pipe outer diameter | 24 | 28 | 30 | 32 | 35 | 38 | 40 | 44 | 48 | 50 |
| Minimum bend radius | 68 | 84 | 90 | 96 | 105 | 114 | 120 | 132 | 144 | 150 |
The relationship between pipe diameter and bending radius and pipe bending method is shown in the following figure
Fig. 8-6 Pipe diameter vs. bend radius and bending method
Note: Sx = wall thickness / tube outside diameter, Rx = bend radius / tube outside diameter
As can be seen from the figure above, the bend deformation depends on the relative bend radius RX and the relative wall thickness SX value. The smaller the RX and SX values, the more deformed, and in the case of extreme conditions, the bending process is destroyed to produce an ellipse. The outer wall ruptures or the inner wall loses stability and wrinkles.
Limited by the local manufacturing process, the curved pipe with the shape of the space curve should be avoided, and the curved pipe shape in the form of a flat straight line plus arc should be used, and the main dimensions such as the length of the straight line segment, the length of the arc, the radius of the arc, and the bending angle should be noted for processing. For the straight section of the pull bend, considering the need for chuck traction, the length of the straight section should not be less than 50mm.