Exhaust gasket riveting compound die

Abstract

The utility model relates to the field of stamping dies, in particular to an exhaust gasket riveting compound die which comprises an upper die mechanism and a lower die mechanism, the upper die mechanism comprises an upper fixing plate, an upper die base and an upper discharging plate, the lower die mechanism comprises a lower base plate, a lower fixing plate, a lower die base and a lower discharging plate, the upper fixing plate is connected with the upper die base, the upper discharging plate is slidably connected to the upper die base, and the lower fixing plate is connected with the lower die base. The lower cushion plate is connected with the lower fixing plate, the lower die base is fixed to the lower fixing plate, the lower discharging plate is connected with the lower die base in a sliding mode, an upper spring is arranged between the upper die base and the upper discharging plate, a lower spring is arranged between the lower discharging plate and the lower die base, the elasticity modulus of the lower spring is larger than that of the upper spring, and a plurality of upper punches are arranged on the upper die base. And the upper punch penetrates through the upper discharging plate. The exhaust gasket machining method has the effect of reducing the number of molds needed when the exhaust gasket is machined.

Description

Technical Field

[0001] This application relates to the field of stamping dies, and in particular to a venting pad riveting compound die. Background Technology

[0002] Stamping dies are tools used to punch holes and grooves into workpieces. By extruding sheet metal, dies can process holes in the sheet metal and bend the edges of the sheet metal, thereby improving processing efficiency.

[0003] The relevant stamping dies include an upper die and a lower die. The upper die includes an upper fixed plate and an upper die base, while the lower die includes a lower fixed plate and a lower die base. The lower fixed plate is fixed to the ground, and the upper fixed plate is connected to a hydraulic cylinder. The hydraulic cylinder drives the upper fixed plate to move vertically back and forth, allowing the upper and lower die bases to jointly clamp the sheet metal and punch holes in it. A punch is mounted on the die base, which is inserted into the through-holes in the sheet metal. Insertion of the punch into the through-holes smooths the surface of the sheet metal and the through-hole openings, improving the surface quality and dimensional accuracy of the workpiece. The upper and lower dies can also clamp and punch the edges of the workpiece, creating a folded edge.

[0004] The aforementioned technical solutions have the following drawbacks: In the production process of workpieces such as exhaust pads, users need to stack and rivet multiple metal plates into a whole, and then perform flanging and edge-flanging work on the exhaust pad. Users need to use a variety of molds of different shapes to process the exhaust pad, and the cost of custom molds is high, resulting in high production costs. Utility Model Content

[0005] In order to reduce the number of molds required when processing exhaust pads, this application provides an exhaust pad riveting composite mold.

[0006] The technical solution for the venting pad riveting composite mold provided in this application is as follows:

[0007] A composite mold for venting pad riveting includes an upper mold mechanism and a lower mold mechanism. The upper mold mechanism includes an upper fixed plate, an upper mold base, and an upper stripper plate. The lower mold mechanism includes a lower pad plate, a lower fixed plate, a lower mold base, and a lower stripper plate. The upper fixed plate is connected to the upper mold base, the upper stripper plate is slidably connected to the upper mold base, the lower pad plate is connected to the lower fixed plate, the lower mold base is fixed to the lower fixed plate, and the lower stripper plate is slidably connected to the lower mold base. An upper spring is provided between the upper mold base and the upper stripper plate, and a lower spring is provided between the lower stripper plate and the lower mold base. The elastic modulus of the lower spring is greater than that of the upper spring. Multiple upper punches are provided on the upper mold base, and the upper punches penetrate the upper stripper plate.

[0008] By adopting the above technical solution, an upper die holder is set on the upper fixed plate, and an upper punch is set on the upper die holder. The user can place the workpiece between the upper and lower stripper plates. The power unit drives the upper fixed plate to move downward, so that the upper and lower stripper plates clamp the workpiece together. As the upper fixed plate continues to move downward, the upper spring gradually contracts, while the lower spring maintains a constant length. The upper punch extends out from the upper stripper plate and can be inserted into the through hole of the workpiece, thereby turning the hole in the workpiece and making the edge of the hole smooth. When the upper spring contracts to its limit position, the power mechanism continues to drive the upper fixed plate to move downward. At this time, the lower spring contracts, and the upper and lower stripper plates move together, thereby achieving the effect of turning the edge of the workpiece. During stamping, the upper die mechanism and the lower die mechanism can complete multiple processes on the workpiece simultaneously, thereby saving the cost of customizing multiple sets of dies.

[0009] Optionally, the lower fixed plate is provided with a plurality of movable punches, which pass through the lower die base and the lower stripper plate. A punch spring is provided at the lower end of the movable punch, and the punch spring is fixed on the lower fixed plate. The positions of the upper punch and the movable punch correspond one-to-one.

[0010] By adopting the above technical solution, a movable punch is set on the lower fixed plate. When the upper die mechanism and the lower die mechanism abut, the upper punch can abut with the movable punch. As the upper spring contracts, the upper punch extends out from the upper unloading plate and performs a hole-turning on the workpiece. When the upper punch abuts with the movable punch, the upper punch penetrates the workpiece, making the inner wall of the workpiece hole flat. When it is necessary to turn the workpiece over, the upper die mechanism moves down and squeezes the lower spring. At this time, the movable punch can squeeze the punch spring and slide down, so that the upper punch and the movable punch maintain structural integrity during the turning process.

[0011] Optionally, the upper unloading plate has a chamfered edge on one side near the lower unloading plate.

[0012] By adopting the above technical solution, and by opening a chamfer on the upper unloading plate, when the workpiece passes through the upper unloading plate, the edge of the workpiece bends and fits against the chamfer plane, thereby reducing the probability of cracks and burrs at the chamfer of the workpiece.

[0013] Optionally, a lower positioning block is fitted onto the movable punch. The lower positioning block has a cylindrical structure and is positioned between the lower unloading plate and the lower die holder.

[0014] By adopting the above technical solution, a lower positioning block is fitted onto the movable punch, which can be locked between the lower stripper plate and the lower die base. When the upper spring contracts to its limit, the upper die structure moves downward and squeezes the lower spring, causing the lower stripper plate to fall. The lower positioning block can support the lower stripper plate, thus fixing the distance between the lower stripper plate and the lower die base. This achieves the effect of controlling the moving distance of the upper and lower stripper plates, thereby facilitating the user's control over the workpiece flanging process.

[0015] Optionally, the upper fixing plate is provided with a plurality of upper equal height sleeves, and the lower fixing plate is provided with a plurality of lower equal height sleeves. The positions of the upper equal height sleeves and the lower equal height sleeves correspond one to one. When the upper spring and the lower spring are contracted to their limit state and the upper unloading plate and the lower unloading plate abut against each other, the upper equal height sleeves and the lower equal height sleeves abut against each other.

[0016] By adopting the above technical solution, by setting an upper equal-height sleeve on the upper fixed plate and a lower equal-height sleeve on the lower fixed plate, the upper equal-height sleeve and the lower equal-height sleeve can abut against each other. When the movement accuracy of the power mechanism is poor, when the upper equal-height sleeve and the lower equal-height sleeve abut against each other, the upper die mechanism is difficult to continue to fall, thereby reducing the probability of the upper punch and the movable punch breaking under stress.

[0017] Optionally, the upper fixed plate is provided with an upper limit post, and the lower fixed plate is provided with a lower limit post. The upper limit post passes through the upper mold base and the upper stripper plate in sequence, and the lower limit post passes through the lower mold base and the lower stripper plate in sequence. The upper limit post is slidably connected to the upper stripper plate, and the lower limit post is slidably connected to the lower stripper plate.

[0018] By adopting the above technical solution, an upper limit post is set on the upper fixed plate and a lower limit post is set on the lower fixed plate. The upper limit post passes through and slides with the upper unloading plate. The upper limit post has the effect of limiting the upper unloading plate, and the lower limit post limits the lower unloading plate. When the upper and lower unloading plates jointly press the workpiece, the upper unloading plate can easily move horizontally relative to the lower unloading plate. By setting the upper and lower limit posts, the stamping quality can be improved.

[0019] Optionally, the upper unloading plate is provided with multiple upper guide pillars, which penetrate the upper mold base. One end of the upper guide pillar is fixed to the upper unloading plate, and the other end is slidably connected to the upper fixed plate. The lower unloading plate is provided with multiple lower guide pillars, which penetrate the lower mold base. One end of the lower guide pillar is fixed to the lower mold base, and the other end is slidably connected to the lower fixed plate.

[0020] By adopting the above technical solution, and by setting an upper guide post on the upper unloading plate, the upper unloading plate is slidably connected to the upper fixed plate through the upper guide post, thereby reducing the tension on the upper spring and increasing the service life of the upper spring.

[0021] Optionally, the lower unloading plate is provided with multiple limiting blocks, and the upper unloading plate is provided with multiple through holes whose positions and sizes correspond to the limiting blocks.

[0022] By adopting the above technical solution, a limiting block is set on the lower unloading plate, which protrudes upward. After a through hole is opened on the workpiece, the workpiece is placed between the upper and lower unloading plates for the turning process. At this time, the limiting block can be inserted into the through hole of the workpiece, thereby keeping the workpiece in a stable position on the lower unloading plate and improving the processing quality of the workpiece.

[0023] In summary, the beneficial technical effects of this application are as follows:

[0024] 1. By setting an upper die holder on the upper fixed plate and an upper punch on the upper die holder, the user can place the workpiece between the upper and lower stripper plates. The power unit drives the upper fixed plate to move downward, so that the upper and lower stripper plates clamp the workpiece together. As the upper fixed plate continues to move downward, the upper spring gradually contracts, while the lower spring remains at a constant length. The upper punch extends out from the upper stripper plate and can be inserted into the through hole of the workpiece, thereby turning the hole in the workpiece and making the edge of the hole smooth. When the upper spring contracts to its limit position, the power mechanism continues to drive the upper fixed plate to move downward. At this time, the lower spring contracts, and the upper and lower stripper plates move together, thereby achieving the effect of turning the edge of the workpiece. During stamping, the upper die mechanism and the lower die mechanism can complete multiple processes on the workpiece simultaneously, thereby saving the cost of customizing multiple sets of dies.

[0025] 2. By setting a movable punch on the lower fixed plate, when the upper die mechanism abuts with the lower die mechanism, the upper punch can abut with the movable punch. As the upper spring retracts, the upper punch extends from the upper stripper plate and performs a hole-turning on the workpiece. When the upper punch abuts with the movable punch, the upper punch penetrates the workpiece, making the inner wall of the workpiece hole flat. When it is necessary to turn the workpiece over, the upper die mechanism moves down and squeezes the lower spring. At this time, the movable punch can squeeze the punch spring and slide down, so that the upper punch and the movable punch maintain structural integrity during the turning process.

[0026] 3. By setting an upper equal-height sleeve on the upper fixed plate and a lower equal-height sleeve on the lower fixed plate, the upper and lower equal-height sleeves can abut against each other. When the movement accuracy of the power mechanism is poor, the upper die mechanism is difficult to continue falling when the upper and lower equal-height sleeves abut against each other, thereby reducing the probability of the upper punch and the movable punch breaking under stress. Attached Figure Description

[0027] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application.

[0028] Figure 2 This is a schematic diagram of the upper mold mechanism in an embodiment of this application.

[0029] Figure 3 This is a schematic diagram of the upper mold base according to an embodiment of this application.

[0030] Figure 4 This is a schematic diagram of the lower mold mechanism according to an embodiment of this application.

[0031] Figure 5 This is a schematic diagram of the structure of the active punch in an embodiment of this application.

[0032] Figure 6 This is a schematic diagram showing the position of the punch spring in an embodiment of this application.

[0033] Reference numerals in the attached drawings: 1. Upper mold mechanism; 11. Upper fixed plate; 111. Upper equal height sleeve; 112. Upper limit post; 12. Upper mold base; 121. Upper punch; 122. Upper guide post; 13. Upper stripper plate; 131. Upper spring; 132. Chamfer; 2. Lower mold mechanism; 21. Lower pad; 22. Lower fixed plate; 221. Lower equal height sleeve; 222. Movable punch; 223. Punch spring; 224. Lower positioning block; 225. Lower limit post; 23. Lower mold base; 232. Lower spring; 233. Lower guide post; 24. Lower stripper plate; 241. Limit block. Detailed Implementation

[0034] The present application will be further described in detail below with reference to the accompanying drawings.

[0035] This application discloses a composite mold for riveting exhaust pads, referring to... Figure 1 It includes an upper mold mechanism 1 and a lower mold mechanism 2. The lower mold mechanism 2 is fixedly set, and the upper mold mechanism 1 is set above the lower mold mechanism 2. A power mechanism is connected to the upper mold mechanism 1. The power mechanism can be a hydraulic cylinder. The hydraulic cylinder drives the upper mold mechanism 1 to move vertically back and forth. The user places the venting pad to be processed between the upper mold mechanism 1 and the lower mold mechanism 2, so that the upper mold mechanism 1 and the lower mold mechanism 2 squeeze the venting pad together, so as to achieve the effect of turning holes and turning edges on the venting pad.

[0036] Reference Figure 2 and Figure 3 The upper mold mechanism 1 includes an upper fixed plate 11, an upper mold base 12, and an upper unloading plate 13. The upper fixed plate 11 is horizontally arranged and connected to the power mechanism. The upper mold base 12 is fixed on the lower surface of the upper fixed plate 11. The upper unloading plate 13 is arranged below the upper mold base 12 and is slidably connected to the upper fixed plate 11. The lower mold mechanism 2 includes a lower pad 21, a lower fixed plate 22, a lower mold base 23, and a lower unloading plate 24. The lower pad 21 is horizontally arranged on the ground. The lower fixed plate 22 is horizontally fixed on the lower pad 21. The lower mold base 23 is fixed on the lower fixed plate 22. The lower unloading plate 24 is arranged above the lower mold base 23 and is slidably connected to the lower fixed plate 22.

[0037] Reference Figure 2 and Figure 3The upper die base 12 is provided with multiple upper punches 121, and the lower die base 23 is provided with multiple movable punches 222. The upper punches 121 are fixed on the upper die base 12 and perpendicular to it. The upper stripper plate 13 has multiple through holes, and the upper punches 121 are inserted into the through holes of the upper stripper plate 13. The movable punches 222 are slidably connected to the lower die base 23. The movable punches 222 are vertically arranged and penetrate the lower die base 23. A punch spring 223 is provided at the bottom of the movable punches 222. The punch spring 223 is coaxially arranged with the movable punches 222. The lower end of the punch spring 223 is fixed in the lower fixed plate 22, and the upper end is connected to the movable punches 222.

[0038] Reference Figure 2 and Figure 3 Multiple upper springs 131 are installed between the upper stripper plate 13 and the upper mold base 12. The upper springs 131 are perpendicular to the upper stripper plate 13, with one end fixed to the upper mold base 12 and the other end fixed to the upper stripper plate 13. Lower springs 232 are installed between the lower stripper plate 24 and the lower mold base 23. The elastic force of the lower springs 232 is greater than that of the upper springs 131. When the power mechanism drives the upper mold mechanism 1 to fall, the upper stripper plate 13 and the lower stripper plate 24 jointly compress the workpiece. As the upper mold mechanism 1 continues to fall, the upper springs 131 contract, while the lower springs 232 maintain their natural length. At this time, the upper punch 121 extends out from the through hole of the upper stripper plate 13 and flips the workpiece. As the upper die mechanism 1 moves, the upper stripper plate 13 gradually comes into contact with the upper die base 12, and the upper punch 121 gradually comes into contact with the end of the movable punch 222. At this time, the upper die mechanism 1 can continue to move down. When the upper die mechanism 1 falls, it squeezes the punch spring 223 and the lower spring 232, so that the lower stripper plate 24 can fall. At this time, the upper stripper plate 13 and the lower stripper plate 24 jointly squeeze the workpiece and achieve the effect of flipping the workpiece.

[0039] Reference Figure 2 and Figure 3 The upper mold mechanism 1 is equipped with multiple upper equal-height sleeves 111, each of which is cylindrical and vertically fixed to the upper fixed plate 11. A lower equal-height sleeve 221 is provided on the lower fixed plate 22 and is vertically fixed to it. The positions of the upper equal-height sleeves 111 and 221 correspond one-to-one. When the upper spring 131, lower spring 232, and lower punch spring 223 are all contracted to their limit positions, the upper equal-height sleeves 111 and 221 abut against each other. At this point, the power mechanism is unlikely to continue driving the upper fixed plate 11 downwards, thus reducing the probability of excessive feed by the power mechanism and damage to the mold and workpiece.

[0040] Reference Figure 2 and Figure 3An upper limit post 112 is fixedly connected to the upper fixed plate 11, and a lower limit post 225 is provided on the lower fixed plate 22. The upper limit post 112 passes through the upper mold base 12 and the upper stripper plate 13 in sequence, and the lower limit post 225 passes through the lower mold base 23 and the lower stripper plate 24 in sequence. The positions of the upper limit post 112 and the lower limit post 225 are staggered. The sliding direction of the upper stripper plate 13 is limited by the upper limit post 112, and the sliding direction of the lower stripper plate 24 is limited by the lower limit post 225. When the upper stripper plate 13 and the lower stripper plate 24 abut against each other and press the workpiece, the probability of the upper stripper plate 13 sliding horizontally relative to the lower stripper plate 24 can be reduced.

[0041] Reference Figure 2 and Figure 3 The upper ejector plate 13 is provided with multiple upper guide pillars 122, which are vertically arranged and penetrate the upper mold base 12. The upper end of the upper guide pillar 122 is slidably connected to the upper fixed plate 11, and the lower end is fixedly connected to the upper ejector plate 13. The lower ejector plate 24 is provided with multiple lower guide pillars 233, which penetrate the lower mold base 23 and are vertically arranged relative to the lower mold base 23. The upper end of the lower guide pillar 233 is fixedly connected to the lower ejector plate 24, and the lower end is slidably connected to the lower fixed plate 22. The upper ejector plate 13 is slidably connected to the upper fixed plate 11 through the upper guide pillars 122, and the lower ejector plate 24 is slidably connected to the lower fixed plate 22 through the lower guide pillars 233.

[0042] Reference Figure 2 and Figure 3 A chamfer 132 is provided on one side edge of the upper stripper plate 13. When the upper end of the upper stripper plate 13 abuts against the upper die base 12 and the lower end abuts against the lower stripper plate 24, the upper die mechanism 1 can continue to move downward and compress the lower spring 232. When the lower spring 232 is compressed, the upper stripper plate 13 and the lower stripper plate 24 punch the edge of the workpiece and achieve a flanging effect. The side of the workpiece near the chamfer 132 can be flanged. By providing the chamfer 132, burrs and cracks can be reduced when the workpiece is flanged.

[0043] Reference Figure 4 , Figure 5 and Figure 6 The movable punch 222 is fitted with a lower positioning block 224, which is a cylindrical structure. The lower positioning block 224 is located between the lower stripper plate 24 and the lower die base 23. When the upper die mechanism 1 and the lower die mechanism 2 squeeze each other, the lower spring 232 contracts. When the lower stripper plate 24 falls onto the lower positioning block 224, the lower stripper plate 24 is difficult to fall further, thus supporting the lower stripper plate 24 and keeping the lower stripper plate 24 at a constant distance from the lower die base 23. By fitting lower positioning blocks 224 of different heights onto the movable punch 222, the user can adjust the moving distance of the lower stripper plate 24, thereby facilitating the control of the workpiece flanging process.

[0044] Reference Figure 4 , Figure 5 and Figure 6 Multiple limiting blocks 241 are provided on the lower unloading plate 24. The lower end of the limiting block 241 is fixed on the lower unloading plate 24, and the upper end extends upward and penetrates through the upper unloading plate 13. When a through hole is opened on the workpiece, the workpiece is placed between the upper unloading plate 13 and the lower unloading plate 24. At this time, the limiting block 241 is inserted into the through hole in the workpiece, thereby achieving the effect of positioning the workpiece. When the upper punch 121 and the movable punch 222 punch the workpiece, the probability of the workpiece sliding horizontally on the lower unloading plate 24 can be reduced.

[0045] The implementation principle of this application embodiment is as follows: By setting an upper mold base 12 on the upper fixed plate 11 and a lower mold base 23 on the lower fixed plate 22, when the power mechanism drives the upper fixed plate 11 to move downward, the upper unloading plate 13 can abut against the lower unloading plate 24. As the power mechanism continues to move, the upper punch 121 can extend out from the through hole of the upper unloading plate 13, thereby achieving the effect of turning the workpiece through hole and making the edge of the workpiece through hole flat. By setting a movable punch 222 on the lower fixed plate 22, the movable punch 222 can slide. When the upper unloading plate 13 abuts against the lower unloading plate 24, the upper spring 131 contracts to the limit state, and the lower spring 232 is in the contracted state. At this time, the power mechanism drives the upper mold mechanism 1 to continue to move downward, which can cause the lower spring 232 to contract and the lower unloading plate 24 to move downward, thereby achieving the effect of turning the workpiece edge.

[0046] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A composite mold for riveting venting pads, characterized in that: The device includes an upper mold mechanism (1) and a lower mold mechanism (2). The upper mold mechanism (1) includes an upper fixed plate (11), an upper mold base (12), and an upper stripper plate (13). The lower mold mechanism (2) includes a lower pad plate (21), a lower fixed plate (22), a lower mold base (23), and a lower stripper plate (24). The upper fixed plate (11) is connected to the upper mold base (12), and the upper stripper plate (13) is slidably connected to the upper mold base (12). The lower pad plate (21) is connected to the lower fixed plate (22), and the lower mold base (23) is connected to the lower mold base (24). Fixed on the lower fixing plate (22), the lower stripper plate (24) is slidably connected to the lower mold base (23), an upper spring (131) is provided between the upper mold base (12) and the upper stripper plate (13), and a lower spring (232) is provided between the lower stripper plate (24) and the lower mold base (23). The elastic modulus of the lower spring (232) is greater than that of the upper spring (131). Multiple upper punches (121) are provided on the upper mold base (12), and the upper punches (121) penetrate the upper stripper plate (13).

2. The exhaust pad riveting composite mold according to claim 1, characterized in that: The lower fixed plate (22) is provided with a plurality of movable punches (222), the movable punches (222) penetrate the lower mold base (23) and the lower unloading plate (24), and the lower end of the movable punches (222) is provided with a punch spring (223), the punch spring (223) is fixed on the lower fixed plate (22), and the positions of the upper punch (121) and the movable punches (222) correspond one-to-one.

3. The venting pad riveting composite mold according to claim 1, characterized in that: The upper unloading plate (13) has a chamfer (132) on one side edge near the lower unloading plate (24).

4. The venting pad riveting composite mold according to claim 2, characterized in that: The movable punch (222) is fitted with a lower positioning block (224), which is a cylindrical structure and is located between the lower unloading plate (24) and the lower die holder (23).

5. The exhaust pad riveting composite mold according to claim 1, characterized in that: The upper fixing plate (11) is provided with a plurality of upper equal height sleeves (111), and the lower fixing plate (22) is provided with a plurality of lower equal height sleeves (221). The positions of the upper equal height sleeves (111) and the lower equal height sleeves (221) correspond one to one. When the upper spring (131) and the lower spring (232) are contracted to their limit state and the upper unloading plate (13) and the lower unloading plate (24) abut against each other, the upper equal height sleeves (111) and the lower equal height sleeves (221) abut against each other.

6. The exhaust pad riveting composite mold according to claim 1, characterized in that: The upper fixed plate (11) is provided with an upper limit post (112), and the lower fixed plate (22) is provided with a lower limit post (225). The upper limit post (112) passes through the upper mold base (12) and the upper unloading plate (13) in sequence, and the lower limit post (225) passes through the lower mold base (23) and the lower unloading plate (24) in sequence. The upper limit post (112) is slidably connected to the upper unloading plate (13), and the lower limit post (225) is slidably connected to the lower unloading plate (24).

7. The exhaust pad riveting composite mold according to claim 1, characterized in that: The upper unloading plate (13) is provided with multiple upper guide pillars (122), which penetrate the upper mold base (12). One end of the upper guide pillar (122) is fixed to the upper unloading plate (13), and the other end is slidably connected to the upper fixing plate (11). The lower unloading plate (24) is provided with multiple lower guide pillars (233), which penetrate the lower mold base (23). One end of the lower guide pillar (233) is fixed to the lower mold base (23), and the other end is slidably connected to the lower fixing plate (22).

8. The venting pad riveting composite mold according to claim 1, characterized in that: The lower unloading plate (24) is provided with multiple limiting blocks (241), and the upper unloading plate (13) is provided with multiple through holes whose positions and sizes correspond to the limiting blocks (241).

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