Drawing dies for automotive rear floor with reinforcing ribs

Abstract

This invention relates to the field of automotive mold technology, and discloses a drawing die assembly for a rear floor of an automobile with reinforcing ribs. The assembly includes a first drawing die assembly and a second drawing die assembly. The first drawing die assembly includes a first drawing die and a first drawing punch arranged opposite each other, and a first pressure plate disposed between the first drawing die and the first drawing punch. The first pressure plate is equipped with a movable punch. The second drawing die assembly includes a second drawing die and a second drawing punch arranged opposite each other, and a second pressure plate disposed between the second drawing die and the second drawing punch. The first drawing die assembly is used to draw and form the protruding portion of the reinforcing rib, and the second drawing die assembly is used to draw and form the recessed portion of the reinforcing rib. This drawing die assembly solves the problem of excessive pressure on the rear floor, shortens the mold development cycle, reduces the pressure on the rear floor, improves the press adaptability, and reduces the workload of adjusting the part size during later part debugging and modification processes.

Description

Technical Field

[0001] This invention relates to the field of automotive mold technology, and more particularly to a drawing die for a rear floor of an automobile with reinforcing ribs. Background Technology

[0002] With the rapid development of the automotive industry, automobiles have become an indispensable means of transportation for people. The number of cars on the road is increasing year by year, and more and more people own private cars. This widespread adoption of automobiles has brought about the development of automotive parts manufacturing and design. The rear floor is an important component of a car, and drawing molds are needed when processing it.

[0003] Most spare tire recesses on rear floorboards are deep and difficult to form. In traditional drawing processes, the trimming line is placed on the drawing punch, and the process is completed along the product boundary to connect with the blank holder. This method further increases the drawing depth, increasing the risk of cracking and necking during drawing, and also results in low material utilization and high material costs. One improved process is to place the product portion outside the spare tire recess on the blank holder to reduce the drawing depth. However, the shape of the product placed on the blank holder is integrally formed during drawing, which can negatively impact the initial flow of the sheet metal. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the first objective of this invention is to provide a drawing die for a car rear floor with reinforcing ribs. By employing a secondary drawing process, the problem of the rear floor being incompatible with the production press due to excessive blanking force can be eliminated. This optimizes the process, shortens the die development cycle, reduces the blanking force of the rear floor, improves the press's compatibility, and reduces the workload of adjusting and modifying the part's dimensions during later stages of part manufacturing.

[0005] To achieve the above objectives, a first aspect of the present invention provides a drawing die for a car rear floor with reinforcing ribs, comprising a first drawing die and a second drawing die; the first drawing die includes a first drawing die and a first drawing punch disposed opposite to each other; a first pressure plate disposed between the first drawing die and the first drawing punch; the first pressure plate is provided with a movable punch, and a first through area of ​​the first drawing punch and a second through area of ​​the movable punch are formed on the first pressure plate; the second drawing die includes a second drawing die and a second drawing punch disposed opposite to each other; a second pressure plate is disposed between the second drawing die and the second drawing punch; a third through area of ​​the second drawing punch is formed on the second pressure plate; the first drawing die is used to draw and form the protruding portion of the reinforcing rib, and the second drawing die is used to draw and form the recessed portion of the reinforcing rib.

[0006] In addition, the drawing die for a car rear floor with reinforcing ribs according to the above embodiments of the present invention may also have the following additional technical features:

[0007] According to some embodiments of the present invention, the movable punch is detachably connected to the first pressure plate.

[0008] According to some embodiments of the present invention, the drawing strokes of the first drawing module and the second drawing module are the same.

[0009] According to some embodiments of the present invention, the first recessed portion of the first drawing die is matched with the shape of the first drawing punch, and the second recessed portion of the first drawing die is matched with the shape of the movable punch.

[0010] According to some embodiments of the present invention, the first drawing die assembly further includes a first upper die holder and a first lower die holder, the first drawing die is detachably disposed on the first upper die holder, the first drawing punch is detachably disposed on the first lower die holder, and the first pressure plate is disposed on the first lower die holder by means of a nitrogen spring.

[0011] According to some embodiments of the present invention, the second drawing die assembly further includes a second upper die holder and a second lower die holder, the second drawing die is detachably disposed on the second lower die holder, the second drawing punch is detachably disposed on the second upper die holder, and the second pressure plate is disposed on the second lower die holder by means of a nitrogen spring.

[0012] According to some embodiments of the present invention, during the first drawing stroke, the sheet metal is placed between the first pressure plate and the first drawing die. The first drawing die moves toward the first drawing punch, and the first pressure plate moves toward the first drawing punch under the drive of the first drawing die. The first pressure plate is in contact with the first lower die seat under the action of a nitrogen spring, so that the first drawing punch passes through the first passing area and the movable punch passes through the second passing area, drawing the raised portion of the reinforcing rib on the sheet metal.

[0013] According to some embodiments of the present invention, during the second drawing stroke, the sheet metal is placed between the second pressure plate and the second drawing die, the second drawing die moves toward the second drawing punch, the second pressure plate moves toward the second drawing punch under the drive of the second drawing die, and the second pressure plate is in contact with the second upper die seat under the action of a nitrogen spring, so that the second drawing punch passes through the third passing area and draws the recessed portion of the reinforcing rib on the sheet metal.

[0014] According to some embodiments of the present invention, the first drawing die is connected to the first upper die holder by screws or pins, and the first drawing punch is connected to the first lower die holder by screws or pins.

[0015] According to some embodiments of the present invention, the second drawing die is connected to the second lower die holder by screws or pins, and the second drawing punch is connected to the second upper die holder by screws or pins.

[0016] According to an embodiment of the present invention, a drawing die assembly for a car rear floor with reinforcing ribs includes a first drawing die assembly and a second drawing die assembly. The first drawing die assembly includes a first drawing die and a first drawing punch disposed opposite to each other; a first pressure plate disposed between the first drawing die and the first drawing punch; the first pressure plate is provided with a movable punch, and a first through-area of ​​the first drawing punch and a second through-area of ​​the movable punch are formed on the first pressure plate; the second drawing die assembly includes a second drawing die and a second drawing punch disposed opposite to each other; a second pressure plate is disposed between the second drawing die and the second drawing punch; a third through-area of ​​the second drawing punch is formed on the second pressure plate; the first drawing die assembly is used to draw and form the protruding portion of the reinforcing rib, and the second drawing die assembly is used to draw and form the recessed portion of the reinforcing rib. Therefore, by adopting a secondary drawing forming process, this drawing die can eliminate the problem of the rear floor being unable to adapt to the production press due to excessive pressure. It optimizes the process, shortens the mold development cycle, reduces the pressure of the rear floor, improves the press adaptability, and reduces the workload of adjusting the size of the parts during the later part debugging and rectification process.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] Figure 1 This is an overall schematic diagram of a drawing module for a car rear floor with reinforcing ribs according to some embodiments of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of a first drawing module according to some embodiments of the present invention;

[0020] Figure 3 This is a schematic diagram of the structure of a second drawing module according to some embodiments of the present invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] The first drawing die 1, the first drawing die 11, the first drawing punch 14, the first pressure plate 13, the movable punch 12, the first crossing area 15, the second crossing area 16, the second drawing die 2, the second drawing die 23, the second drawing punch 21, the second pressure plate 22, and the third crossing area 24. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this invention should have the ordinary meaning understood by those skilled in the art. The terms "first," "second," and similar terms used in the embodiments of this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0025] As described in the background section, the rear floor is a common structural component in the lower body of commercial vehicles and passenger cars. Compared to the main press line for the rear floor and its body panels, the press line for the rear floor typically has a press tonnage of around 1000 tons. The lower air cushion can provide a pressing force of around 200 tons. According to traditional processes, the convex shape is formed on the drawing punch, and other areas serve as the pressing surface. This leads to a sharp increase in pressing force, generally reaching around 300 tons, far exceeding the rated pressing force of the press. If a larger tonnage press is used, the smaller size of the die itself will affect the press accuracy and cause unnecessary energy waste during prolonged use.

[0026] Since the rear floor is a large flat area with a raised bulge, in order to increase the rigidity of the part, it is often necessary to add reinforcing ribs to the flat area during product design, and use the entire flat area of ​​the rear floor as the pressing surface.

[0027] In the process of developing this invention, the applicant discovered that because the pressing surface has reinforcing ribs, the pressing force when the pressing surface is closed is generally above 300 tons. This pressing force is often too large for the press it is used with, frequently exceeding the pressure limit of the lower air cushion. Current technical solutions often require reducing the height of the reinforcing ribs and enlarging the protrusions and concavities of the reinforcing ribs to reduce the pressing force. However, such modifications affect the rigidity of the product and increase the difficulty of controlling the product's rebound.

[0028] The drawing module for a car rear floor with reinforcing ribs, as proposed in the embodiments of the present invention, is described below with reference to the accompanying drawings.

[0029] refer to Figure 1This is an overall schematic diagram of a drawing module for a car rear floor with reinforcing ribs according to some embodiments of the present invention.

[0030] The present invention provides a drawing module for a car rear floor with reinforcing ribs, comprising a first drawing module 1 and a second drawing module 2.

[0031] refer to Figure 2 The first drawing die 1 is a schematic diagram of the structure of a first drawing die 1 according to some embodiments of the present invention. The first drawing die 1 includes a first drawing die 11 and a first drawing punch 14 disposed opposite to each other, a first pressure plate 13 disposed between the first drawing die 11 and the first drawing punch 14, the first pressure plate 13 is provided with a movable punch 12, the movable punch 12 is detachably connected to the first pressure plate 13, a first through area 15 of the first drawing punch 14 and a second through area 16 of the movable punch 12 are provided on the first pressure plate 13, and the first drawing die 1 is used to draw and form the protruding part of the reinforcing rib.

[0032] The first drawing die 1 also includes a first upper die holder and a first lower die holder (not shown in the figure). The first drawing die 11 is detachably mounted on the first upper die holder, the first drawing punch 14 is detachably mounted on the first lower die holder, and the first pressure plate 13 is mounted on the first lower die holder by a nitrogen spring.

[0033] In some embodiments, a nitrogen spring is a pressure source. Besides a nitrogen spring, a nitrogen cylinder can also be used as the pressure source. The pressure curve of a nitrogen cylinder is relatively flat, a characteristic that is ideal for drawing die blanks. Theoretically, drawing die blanks require a constant blanking force. The characteristic of a nitrogen cylinder is that it initially has a relatively large force, which increases only slightly as it is compressed, thus facilitating the flow of the drawing blank and achieving satisfactory drawing quality. The nitrogen cylinder has stable performance because its force can remain constant, the same as that of a nitrogen cylinder of the same specification, and is unaffected by external factors. Therefore, it can improve and stabilize the quality of stamped parts.

[0034] The first drawing die 11 can be connected to the first upper die holder by screws or pins to fix the first drawing die 11 to the first upper die holder. The first drawing punch 14 can also be connected to the first lower die holder by screws or pins to fix the first drawing punch 14 to the first lower die holder.

[0035] The main advantages of screw connections are ease of disassembly and maintenance, the ability to withstand greater connecting forces, and the ability to control adjustment and tightening forces. Pin connections are a commonly used non-disassembly connection method, connecting two or more workpieces through the insertion and fixation of pins. The main advantages of pin connections are simple connection, compact structure, and lower cost; pin connections can also achieve a certain degree of displacement and axial fixation.

[0036] During the first drawing stroke, the sheet metal is placed between the first pressure plate 13 and the first drawing die 11. The first drawing die 11 moves toward the first drawing punch 14. The first pressure plate 13 first moves toward the first drawing die 11. When the first drawing die 11 and the first pressure plate 13 are engaged, the first pressure plate 13 moves toward the first drawing punch 14 under the drive of the first drawing die 11. The first pressure plate 13 is in contact with the first lower die seat under the action of the nitrogen spring, so that the first drawing punch 14 passes through the first crossing area 15 and the movable punch 12 passes through the second crossing area 16, drawing and forming the protruding part of the reinforcing rib on the sheet metal.

[0037] refer to Figure 3 The diagram below shows the structure of a second drawing die 2 according to some embodiments of the present invention. The second drawing die 2 includes a second drawing die 23 and a second drawing punch 21 disposed opposite to each other, a second pressure plate 22 disposed between the second drawing die 23 and the second drawing punch 21, and a third through area 24 of the second drawing punch 21 is provided on the second pressure plate 22. The second drawing die 2 is used to draw and form the recessed portion of the reinforcing rib.

[0038] The second drawing die 2 also includes a second upper die holder and a second lower die holder (not shown in the figure). The second drawing die 23 is detachably mounted on the second lower die holder, the second drawing punch 21 is detachably mounted on the second upper die holder, and the second pressure plate 22 is mounted on the second lower die holder via a nitrogen spring.

[0039] The second drawing die 23 can be connected to the second lower die holder by screws or pins to fix the second drawing die 23 to the second lower die holder. The second drawing punch 21 can also be connected to the second upper die holder by screws or pins to fix the second drawing punch 21 to the second upper die holder.

[0040] During the second drawing stroke, the sheet metal is placed between the second pressure plate 22 and the second drawing die 23. The second drawing die 23 moves toward the second drawing punch 21. The second pressure plate 22 moves toward the second drawing punch 23 under the drive of the second drawing die 21. The second pressure plate 22 is in contact with the second upper die seat under the action of the nitrogen spring, so that the second drawing punch 21 passes through the third passing area 24 and draws the recessed part of the reinforcing rib on the sheet metal.

[0041] The drawing strokes of the first drawing module 1 and the second drawing module 2 are the same. The drawing stroke of the first drawing module 1 is controlled by the physical stroke difference between the first pressure plate 13 and the movable punch 12.

[0042] Maintaining consistent drawing strokes in both the first drawing module 1 and the second drawing module 2 is crucial for ensuring the stability and accuracy of the entire drawing process. During drawing, the sheet metal undergoes complex deformation. Inconsistent drawing strokes between the two modules can lead to uneven deformation at different stages, affecting the shape and quality of the final product. Consistent strokes ensure uniform stress distribution on the sheet metal during drawing, reducing defects such as cracking and wrinkling caused by stress concentration. Therefore, a stable drawing stroke helps control the dimensional and shape accuracy of the product, ensuring it meets design requirements.

[0043] Specifically, when designing the first drawing die 1 and the second drawing die 2, it is necessary to accurately calculate and set the stroke parameters of the die to ensure that the first drawing die 1 and the second drawing die 2 can maintain a consistent motion trajectory based on consistent stroke parameters during the drawing process. The physical strokes of the first pressure plate 13 and the movable punch 12 cooperate with each other to form the drawing stroke of the first drawing die 1.

[0044] The first recessed portion of the first drawing die 11 is fitted with the shape of the first drawing punch 14 so that the sheet metal can be drawn to form the protruding portion of the reinforcing rib. The second recessed portion of the first drawing die 11 is fitted with the shape of the movable punch 12 so that the sheet metal can be drawn to form the recessed portion of the reinforcing rib.

[0045] As a specific embodiment, the press lower air cushion needs to have a locking function. The press lower air cushion is used to prevent wrinkling during stretching and can also be used as a top material or for forming the bottom or part of the workpiece. The locking principle is as follows: when the piston of the hysteresis cylinder descends to the lower chamber (slider angle is 175°), the solenoid valve is energized, and gas enters the locking cylinder, pushing the piston forward to close the connecting pipe. This prevents the hydraulic oil in the upper chamber of the hysteresis cylinder from returning to the lower chamber, resulting in a locking phenomenon (the top crown sinks). (Slider angle is 240°) The solenoid valve is de-energized, and air enters the stretching pad cylinder, driving the piston of the hysteresis cylinder upward to move the hydraulic oil in the upper chamber of the hysteresis cylinder, pushing the locking cylinder (piston returns to its original position, hydraulic oil returns to the lower chamber of the hysteresis cylinder through the connecting pipe, and the top crown rises). The press lower air cushion locking function prevents accidental injury due to misoperation, prevents accidents caused by equipment failure, improves work efficiency, and enhances the working comfort of operators. The press lower air cushion locking is an important safety device, widely used in various press equipment, providing effective protection for the personal safety of operators.

[0046] As a specific embodiment, in a car rear floor with reinforcing ribs, the height difference between the convex area and the flat area of ​​the rear floor is determined. When the height difference between the convex area and the flat area of ​​the rear floor is less than or equal to 100mm, the convex area of ​​the rear floor is drawn and formed by normal drawing. That is, the flat blank that has been pre-cut into a certain shape is drawn into a three-dimensional hollow part by using a drawing die under the pressure of a press to obtain the convex area of ​​the rear floor.

[0047] When the height difference between the convex area and the flat area of ​​the rear floor is greater than 100mm, the convex area of ​​the rear floor is formed by semi-open drawing. The steps are as follows: First, the die is opened on the machine tool, with the upper die pressing core protruding 6-10mm from the upper die pressing surface area, and the lower die pressing ring 6-10mm below the upper surface of the punch. Second, the sheet material is placed in the die positioning area. Third, the machine tool starts, the slide descends, and first the upper die pressing core contacts the sheet material, locking it onto the upper surface of the lower punch and initially forming it. Fourth, the slide continues to descend, and the upper die pressing surface area presses the sheet material on the other side onto the lower pressing ring, beginning to stretch the side surface of the part and continuing the drawing process. Fifth, the slide reaches the lower stop point, the upper and lower dies are completely locked, and the part is formed, resulting in the convex area of ​​the rear floor.

[0048] In summary, the drawing die assembly for a car rear floor with reinforcing ribs according to embodiments of the present invention includes a first drawing die assembly and a second drawing die assembly; the first drawing die assembly includes a first drawing die and a first drawing punch disposed opposite to each other; a first pressure plate disposed between the first drawing die and the first drawing punch; the first pressure plate is provided with a movable punch, and a first through area of ​​the first drawing punch and a second through area of ​​the movable punch are formed on the first pressure plate; the second drawing die assembly includes a second drawing die and a second drawing punch disposed opposite to each other; a second pressure plate is disposed between the second drawing die and the second drawing punch; a third through area of ​​the second drawing punch is formed on the second pressure plate; the first drawing die assembly is used to draw and form the protruding portion of the reinforcing rib, and the second drawing die assembly is used to draw and form the recessed portion of the reinforcing rib. Therefore, by adopting a secondary drawing forming process, this drawing die can eliminate the problem of the rear floor being unable to adapt to the production press due to excessive pressure. It optimizes the process, shortens the mold development cycle, reduces the pressure of the rear floor, improves the press adaptability, and reduces the workload of adjusting the size of the parts during the later part debugging and rectification process.

[0049] It should be noted that the above description describes some embodiments of the present invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the above embodiments and still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0050] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this invention should have the ordinary meaning understood by those skilled in the art. The terms "first," "second," and similar terms used in the embodiments of this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0051] While the spirit and principles of the invention have been described with reference to several specific embodiments, it should be understood that the invention is not limited to the disclosed specific embodiments, and the division of aspects does not imply that features in these aspects cannot be combined for benefit; such division is merely for ease of description. The invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the appended claims is to be interpreted in the broadest sense, thereby encompassing all such modifications and equivalent structures and functions.

Claims

1. A drawing die for a car rear floor with reinforcing ribs, characterized in that, It includes a first drawing module (1) and a second drawing module (2); The first drawing die (1) includes a first drawing die (11) and a first drawing punch (14) disposed opposite to each other; a first pressure plate (13) disposed between the first drawing die (11) and the first drawing punch (14); the first pressure plate (13) is provided with a movable punch (12), and a first through area (15) of the first drawing punch (14) and a second through area (16) of the movable punch (12) are opened on the first pressure plate (13); The second drawing die (2) includes a second drawing die (23) and a second drawing punch (21) disposed opposite to each other; a second pressure plate (22) disposed between the second drawing die (23) and the second drawing punch (21); and a third through area (24) of the second drawing punch (21) is provided on the second pressure plate (22); The first drawing die (1) is used to draw and form the protruding part of the reinforcing rib, and the second drawing die (2) is used to draw and form the recessed part of the reinforcing rib.

2. The drawing die for a car rear floor with reinforcing ribs according to claim 1, characterized in that, The movable punch (12) is detachably connected to the first pressure plate (13).

3. The drawing die for a car rear floor with reinforcing ribs according to claim 1, characterized in that, The first drawing module (1) and the second drawing module (2) have the same drawing stroke.

4. The drawing die for a car rear floor with reinforcing ribs according to claim 1, characterized in that, The first recessed portion of the first drawing die (11) matches the shape of the first drawing punch (14), and the second recessed portion of the first drawing die (11) matches the shape of the movable punch (12).

5. The drawing die for a car rear floor with reinforcing ribs according to claim 1, characterized in that, The first drawing die assembly (1) further includes a first upper die holder and a first lower die holder. The first drawing die (11) is detachably mounted on the first upper die holder, the first drawing punch (14) is detachably mounted on the first lower die holder, and the first pressure plate (13) is mounted on the first lower die holder via a nitrogen spring.

6. The drawing die for a car rear floor with reinforcing ribs according to claim 1, characterized in that, The second drawing die assembly (2) further includes a second upper die holder and a second lower die holder. The second drawing die (23) is detachably mounted on the second lower die holder, the second drawing punch (21) is detachably mounted on the second upper die holder, and the second pressure plate (22) is mounted on the second lower die holder via a nitrogen spring.

7. The drawing die for a car rear floor with reinforcing ribs according to claim 5, characterized in that, During the first drawing stroke, the sheet metal is placed between the first pressure plate (13) and the first drawing die (11). The first drawing die (11) moves toward the first drawing punch (14). The first pressure plate (13) moves toward the first drawing punch (14) under the action of the first drawing die (11). The first pressure plate (13) is in contact with the first lower die seat under the action of the nitrogen spring, so that the first drawing punch (14) passes through the first crossing area (15) and the movable punch (12) passes through the second crossing area (16), drawing the raised part of the reinforcing rib on the sheet metal.

8. The drawing die for a car rear floor with reinforcing ribs according to claim 6, characterized in that, During the second drawing stroke, the sheet metal is placed between the second pressure plate (22) and the second drawing die (23). The second drawing die (23) moves toward the second drawing punch (21). The second pressure plate (22) moves toward the second drawing punch (21) under the drive of the second drawing die (23). The second pressure plate (22) is in contact with the second upper die seat under the action of the nitrogen spring, so that the second drawing punch (21) passes through the third passing area (24) and draws the recessed portion of the reinforcing rib on the sheet metal.

9. The drawing die for a car rear floor with reinforcing ribs according to claim 5, characterized in that, The first drawing die (11) is connected to the first upper die base by screws or pins, and the first drawing punch (14) is connected to the first lower die base by screws or pins.

10. The drawing die for a car rear floor with reinforcing ribs according to claim 6, characterized in that, The second drawing die (23) is connected to the second lower die base by screws or pins, and the second drawing punch (21) is connected to the second upper die base by screws or pins.

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