JP7558818B2 - Press machine and workpiece forming method - Google Patents

Description

This disclosure relates to a press machine and a workpiece forming method, and in particular to a press machine and a workpiece forming method suitable for performing thickness increasing processing to increase the wall thickness of a workpiece.

A press machine that performs thickening processing to increase the thickness of a workpiece is known (see, for example, Patent Document 1). In this machine, the workpiece is clamped and restrained vertically between a lower die and an upper die, and in this state the side end of the workpiece is pressed horizontally with a thickening die to thicken the workpiece. A clearance is provided between the workpiece before thickening and at least one of the lower die and upper die, and the material of the workpiece is forced into this clearance to thicken the workpiece.

JP 2012-121034 A JP 2011-20173 A Japanese Utility Model Publication No. 64-6998

However, during the thickening process, a force is generated that separates the lower and upper dies from each other. If this force actually causes the lower and upper dies to separate, the dimensions and shape of the clearance will change, and there is a risk that the desired thickening shape will not be obtained.

Therefore, this disclosure was devised in consideration of the above circumstances, and its purpose is to provide a press machine and a workpiece forming method that can suppress the separation of the lower and upper dies during thickness-increasing processing.

According to one aspect of the present disclosure,
The lower mold and
An upper mold that can be raised and lowered relative to the lower mold and that sandwiches a workpiece between the upper mold and the lower mold;
a thickness increasing die for horizontally pressing the workpiece sandwiched between the lower die and the upper die to increase the thickness of the workpiece;
a locking mechanism that locks the lower die and the upper die so that they do not separate from each other during thickening processing;
A press machine comprising:

Preferably, the locking mechanism comprises:
A lower die side engagement portion provided on the lower die;
An upper die side engagement portion provided on the upper die;
a locking member that is provided so as to be movable in a horizontal direction and that can simultaneously engage with the lower die side engaging portion and the upper die side engaging portion;
Equipped with.

Preferably, the lower die side engagement portion is formed by a lower die side protrusion provided so as to protrude from a side portion of the lower die,
the upper die side engaging portion is formed by an upper die side protruding portion provided on a side portion of the upper die,
The locking member has a pair of engaging protrusions that sandwich the lower die side protrusion and the upper die side protrusion from above and below when engaged.

The locking mechanism preferably includes a return spring that biases the locking member in the release direction.

Preferably, the press machine comprises:
An upper die support member;
an extension mechanism that connects the upper mold to the upper mold support member so that the upper mold can be raised and lowered;
Equipped with
The locking mechanism includes a pressing member that is provided on the upper die supporting member and presses the locking member toward the engagement side when the upper die supporting member is lowered.

Preferably, the locking mechanism has inclined cam surfaces provided on the locking member and the pressing member, respectively, that can slide against each other.

According to another aspect of the present disclosure,
A method for forming a workpiece using the press machine, comprising the steps of:
A first step of pressing the workpiece into a predetermined shape;
A second step of clamping the workpiece after press working between the lower die and the upper die;
a third step of locking the lower mold and the upper mold by the lock mechanism so that they do not separate from each other;
A fourth step of pressing the workpiece horizontally with the thickening die to thicken the workpiece;
A method for forming a workpiece is provided, comprising the steps of:

According to the present disclosure, it is possible to prevent the lower and upper dies from separating during thickening processing.

FIG. 1 is a front view showing a press machine of the present embodiment. FIG. 2 is a perspective view showing a workpiece according to the present embodiment. FIG. 2 is a front view showing the press machine during press working. FIG. 4 is a front view showing the press machine when press working is completed. FIG. 1 is a front view showing a press machine when locking starts. FIG. 2 is a front view showing the press machine in a locked state. FIG. 11 is a front view showing the press machine when locking is completed. FIG. 4 is a front view showing the press machine during thickness increasing processing. FIG. 11 is a front view showing the press machine at the end of thickening processing. FIG. 4 is a side cross-sectional view showing a workpiece during press working. FIG. 2 is a side cross-sectional view showing the workpiece before thickness-increasing processing. FIG. 4 is a side cross-sectional view showing the workpiece after thickness-increasing processing. 13 is a graph showing spring characteristics of the expansion and contraction mechanism. FIG. 11 is a partial front view showing a press machine according to a modified example.

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. Please note that the present disclosure is not limited to the following embodiments.

Figure 1 shows a press machine M of this embodiment. For convenience, the front-rear, left-right, top-bottom directions are defined as shown in the figure. However, please note that these directions are defined merely for convenience of explanation. In the illustrated example, the top-bottom direction coincides with the vertical direction. The front-rear and left-right directions are included in the horizontal direction.

The central axis (called the machine axis) of the press machine M is indicated by the symbol C. The machine axis C extends in the vertical direction. Unless otherwise specified, hereinafter, the axial direction, radial direction, and circumferential direction based on the machine axis C will simply be referred to as the axial direction, radial direction, and circumferential direction.

The press machine M is formed by a hydraulic press machine and includes a lower die 1 and an upper die 2 that can be raised and lowered relative to the lower die 1. The lower die 1 is fixed to the upper surface of a bolster (not shown) or the like, which is the fixed side of the press machine M. The lower die 1 includes a die 3 that contacts the workpiece W to actually shape the workpiece W, and a die holder 4 that fixes the die 3.

The upper die 2 is arranged above the lower die 1 so that it can rise and fall and move closer to and away from the workpiece W. The upper die 2 includes a forming punch 5 as a first punch that contacts the workpiece W and cooperates with the die 3 to actually form the workpiece W, and a punch holder 6 that fixes the punch 5.

Now, referring to FIG. 2, the forming sequence of the workpiece W will be described. In this embodiment, the workpiece W in its initial state or before forming is a simple rectangular plate material as shown in FIG. 2(A), specifically a blank material or sheet metal with a thickness t1 made of a metal material such as iron or aluminum. This workpiece W is bent into a U-shape or semicircle in cross section as shown in FIG. 2(B), and is formed by pressing so as to have a semicircular pipe shape as a whole. Next, this workpiece W is thickened by thickening processing as shown in FIG. 2(C). That is, the front part Wf is thickened in the thickness direction in a stepped manner so that the thickness t2 of the front part Wf in the front-rear direction (longitudinal direction) of the workpiece W is thicker than the thickness t1 of the rear part Wr. At this time, the thickening is performed only in the inner diameter direction, not in the outer diameter direction. This results in a clean appearance with a constant outer diameter.

For example, the workpiece W after thickening may be welded together in pairs, top and bottom, to form a circular pipe as a whole, and another pipe may be butt-welded to the front end face of this circular pipe. In this case, if the entire workpiece W is thickened to increase the strength of the weld, the weight will also increase. For this reason, only a portion of the workpiece W is thickened as in this embodiment for the purpose of reducing weight. This makes it possible to achieve both increased strength and reduced weight.

In this embodiment, the press working (or U-shaped bending) process in FIG. 2(B) and the thickening process in FIG. 2(C) are performed using different punches 5. The punch 5 used in the press working process is shown in FIG. 1. The punch used in the thickening process will be described later.

As shown in FIG. 1, the forming surfaces 3A, 5A of the die 3 and punch 5 are formed to have a U-shaped or semicircular cross section to match the shape of the workpiece W (FIG. 2(B)) after pressing. The die 3 has a forming groove 11 with a U-shaped cross section extending in the front-rear direction. The die 3 is fitted and fixed in a die fixing hole 7 provided in the center of the die holder 4. An ejection pad 8 that can be raised and lowered and can appear and disappear in the forming groove 11 is provided at the bottom of the die 3. The pad 8 is driven to rise and fall by a pad driving device (not shown) such as a hydraulic type. In this embodiment, two pads 8 are provided to push up the front part Wf and the rear part Wr, respectively (see FIG. 10).

The press machine M includes an upper die support member 9 and an extension mechanism 10 that connects the upper die 2 to the upper die support member 9 so that it can be raised and lowered. The upper die support member 9 is disposed above the upper die 2 and is fixed to the underside of a slide (not shown) or the like which is the movable side of the press machine M. In this embodiment, the extension mechanism 10 is formed of a gas spring and is disposed so that it can extend and contract in the vertical direction. The extension mechanism 10 is disposed between the upper die support member 9 and the punch holder 6 and connects their central parts so that they can move toward and away from each other. The gas pressure inside the extension mechanism 10 can be controlled by a pressure control device (not shown).

The press machine M also has a locking mechanism 20 that locks the lower die 1 and the upper die 2 so that they do not separate from each other during thickening processing.

The locking mechanism 20 includes a lower die side engaging portion provided on the lower die 1, an upper die side engaging portion provided on the upper die 2, and a locking member 21 that is horizontally movable and can simultaneously engage with the lower die side engaging portion and the upper die side engaging portion.

The lower die side engagement portion is formed by a lower die side convex portion 22 that protrudes from the side of the lower die 1. The upper die side engagement portion is formed by an upper die side convex portion 23 that protrudes from the side of the upper die 2. The locking member 21 has a pair of engagement convex portions 24, 25 that sandwich the lower die side convex portion 22 and the upper die side convex portion 23 from above and below when engaged (see Figure 7).

The lower mold side convex portion 22, the upper mold side convex portion 23, the locking member 21, and the engaging convex portions 24 and 25 are arranged symmetrically with respect to the machine axis C. Therefore, for the sake of convenience, only the configuration on the right side will be described here, and the configuration on the left side will not be described.

The die holder 4 of the lower die 1 has an upper surface 26, an inner wall 27 standing on the end of the upper surface 26 on the inner side in the left-right direction (the side of the machine axis C), and an outer wall 28 standing on the end of the upper surface 26 on the outer side in the left-right direction (the side opposite the machine axis C). The upper surface 26, the inner wall 27, and the outer wall 28 are also arranged symmetrically with respect to the machine axis C. Therefore, only the configuration on the right side will be described.

The upper surface 26 is a horizontal flat surface on which the locking member 21 is disposed so as to be slidable in the left-right direction. The left side (inner in the left-right direction) of the inner wall 27 defines part of the upper side of the die fixing hole 7 mentioned above. The lower die side protrusion 22 protrudes from the upper end of the inner wall 27 toward the right side (outer in the left-right direction). The lower die side protrusion 22 in the illustrated example has a rectangular cross section.

The upper die side protrusion 23 protrudes to the right from the lower end of the right side surface of the punch holder 6. This upper die side protrusion 23 also has a rectangular cross section. The position of the right end of the upper die side protrusion 23 in the left-right direction is set to be equal to the position of the right end of the lower die side protrusion 22.

The lower engaging protrusion 24 of the locking member 21 protrudes leftward from the lower end of the left side surface of the locking member 21. Similarly, the upper engaging protrusion 25 of the locking member 21 protrudes leftward from the upper end of the left side surface of the locking member 21. These engaging protrusions 24, 25 also have a rectangular cross section.

The locking mechanism 20 is provided with a pressing member 29 that is provided on the upper die support member 9 and presses the locking member 21 towards the engagement side, i.e., inward in the left-right direction, when the upper die support member 9 descends. The locking mechanism 20 also has inclined cam surfaces 30, 31 that are provided on the locking member 21 and the pressing member 29, respectively, and that can slide against each other. These pressing members 29 and inclined cam surfaces 30, 31 are also provided symmetrically with respect to the machine axis C, so only the configuration on the right side will be described.

The pressing member 29 is positioned to the right of the punch holder 6 so as not to interfere with the punch holder 6, and extends downward from the bottom surface of the upper die support member 9. The inclined cam surface 31 of the pressing member 29 is formed by cutting out the corner of the lower and left end of the pressing member 29 at an angle. The inclined cam surface 31 is inclined toward the right as it goes downward.

The inclined cam surface 30 of the locking member 21 is formed by cutting out the corner at the top right end of the locking member 21 at an angle. The inclined cam surface 30 also slopes downward toward the right and is parallel to the inclined cam surface 31 of the pressing member 29.

The locking mechanism 20 is equipped with a return spring 32 that biases the locking member 21 toward the release side, i.e., outward in the left-right direction. The return springs 32 are also provided symmetrically with respect to the machine axis C, so only the configuration on the right side will be described.

In this embodiment, the return spring 32 is formed of a coil spring. A cylindrical spring receiving hole 33 with a bottom is formed at the lower end of the left side surface of the outer wall 28, and the return spring 32 is arranged in this hole so that it can expand and contract in the left-right direction.

The right end of the return spring 32 is fixed to the outer wall 28, and the left end of the return spring 32 is fixed to the locking member 21. The return spring 32 is normally contracted to pull the locking member 21 to the right. As a result, the locking member 21 normally waits in the rightmost release position as shown in FIG. 1. At this time, the locking member 21 is positioned to the right of the punch holder 6 so as not to interfere with the punch holder 6, and abuts against the outer wall 28 to stop its movement.

Next, we will explain the other punches and thickening dies used in the thickening processing process mentioned above. These other punches and thickening dies are also components of the press machine M.

5 and 11 show a pressure punch 35 as a second punch, i.e., another punch used in place of the punch 5. The pressure punch 35 has a rear portion 35R corresponding to the rear portion Wr of the workpiece W, and a front portion 35F corresponding to the front portion Wf of the workpiece W. When considering the cross-sectional shape as viewed from the front as shown in FIG. 5, the cross-sectional shape of the U-shaped bottom of the rear portion 35R is the same as that of the punch 5. However, the cross-sectional shape of the U-shaped bottom of the front portion 35F is slightly smaller than that of the punch 5. Therefore, as shown in FIG. 11, a clearance L is formed between the front portion 35F and the workpiece W after pressing.

The size of the gap G between the front portion 35F and the die 3 is equal to the thickness t2 of the front portion Wf of the workpiece W after the thickening (G = t2). The size of the clearance L means the thickness of the front portion Wf that has increased due to the thickening. In other words, L = t2 - t1.

At the upper end positions of the U-shaped bottom surfaces of the front portion 35F and the rear portion 35R, upper end holding portions 45 are provided that protrude outward in a stepped manner in the left-right direction. The upper end holding portions 45 regulate the rise of the material during thickening processing, and prevent the position of the upper end surface of the front portion Wf of the workpiece W from becoming higher than the position of the upper end surface of the rear portion Wr. The upper end holding portions 45 are provided over the entire front-to-rear length of the holding punch 35.

As shown in FIG. 12, the thickening mold is formed by a thickening punch 36 as a third punch that is inserted horizontally from the front into the gap G between the front portion 35F and the die 3. Although not shown, the thickening punch 36 has a U-shaped or semicircular cross-sectional shape in a front view that is approximately the same as the cross-sectional shape of the front portion Wf of the workpiece W after thickening when viewed from the front. When the thickening punch 36 is inserted into the gap G, it presses the entire front end surface of the workpiece W. Then, the material of the workpiece W deforms and fills the clearance L, and the front portion Wf of the workpiece W is thickened. This achieves thickening processing, which is a type of forging. The thickening punch 36 is driven by a hydraulic device, not shown.

Next, a description will be given of a workpiece forming method using the press machine M. The workpiece forming method of this embodiment generally includes the following steps.
(1) The first step is to press the workpiece W into a predetermined shape.
(2) A second step in which the workpiece W after press working is clamped between the lower die 1 and the upper die 2.
(3) A third step of locking the lower mold 1 and the upper mold 2 by the lock mechanism 20 so that they do not separate from each other.
(4) A fourth step of increasing the thickness of the workpiece W by pressing the workpiece W horizontally with a thickness increasing die.

First, the first step will be described. First, the press machine M is set to the initial state as shown in Figure 1, and a flat workpiece W before forming is set on this press machine M. At this time, the slide and upper die support member 9 of the press machine M are in the initial position of the top dead center, and the telescopic mechanism 10 is in the most extended state. The workpiece W is placed on the forming groove 11 of the die 3 in a state in which it has been preheated to a high temperature (for example, about 800°C). The locking mechanism 20 is in the released state, and the locking member 21 is positioned in the release position on the outer left-right direction.

From this state, as shown in Figure 3, the slide and upper die support member 9 of the press machine M are lowered. Then, the punch 5 pushes the workpiece W into the forming groove 11, and then the workpiece W is sandwiched between the punch 5 and the die 3 and crushed, bending it into a U-shaped cross section. In this way, the workpiece W is pressed into a U-shaped cross section as shown in Figure 2 (B). After pressing, the workpiece W maintains its original thickness t1. In other words, the workpiece W is formed into a U-shaped cross section while maintaining its initial thickness t1.

At the end of the pressing process, the punch holder 6 is in contact with or slightly spaced apart from the upper surface of the inner wall 27 of the die holder 4.

During press working, an upward workpiece forming reaction force F1 acts on the telescopic mechanism 10 through the punch 5 and punch holder 6, causing the telescopic mechanism 10 to contract. However, for the reasons described below, the telescopic mechanism 10 resists this force F1 and maintains its extended state. This prevents the telescopic mechanism 10 from contracting due to the workpiece forming reaction force F1, ensuring reliable forming.

Figure 13 shows the spring characteristics of the telescopic mechanism 10. The horizontal axis shows the force A acting on the telescopic mechanism 10 in the contraction direction, and the vertical axis shows the contraction amount B of the telescopic mechanism 10. The load at which the telescopic mechanism 10 starts to contract is A0, and the magnitude of this load A0 is determined by the gas pressure inside the telescopic mechanism 10. If the external force acting on the telescopic mechanism 10 is equal to or less than load A0, the telescopic mechanism 10 does not contract, and the contraction amount B is zero. If the external force acting on the telescopic mechanism 10 exceeds load A0, the contraction amount B of the telescopic mechanism 10 increases in response to the increase in external force.

In this embodiment, the load A0 is set and controlled so that it is higher than the workpiece forming reaction force F1. Therefore, the telescopic mechanism 10 does not shrink during workpiece forming, and forming can be performed without any problems.

By the way, during press processing, a downward force F2 that is approximately equal to the workpiece forming reaction force F1 is naturally applied to the upper die support member 9 of the press machine M from a hydraulic device (not shown).

Figure 10 shows a side cross-sectional view at the position of the machine axis C, which corresponds to Figure 3. As shown in the figure, the workpiece W is sandwiched and contacted between the punch 5 and the die 3 over its entire front-to-rear length.

Next, as shown in Figure 4, the upper die support member 9 is raised to the top dead center and then paused there. This causes the punch 5 to be pulled out of the die 3. This completes the first step.

Next, the second step is started. At this time, as shown in FIG. 5, the punch 5 is first removed and replaced with another pressing punch 35. By replacing the punch in this way, it is possible to perform thickness increasing processing with a single press machine M. The punch 5 and pressing punch 35 are detachably attached to the punch holder 6 by bolts or the like.

Next, as shown in Figure 6, the upper die support member 9 is lowered to the same height as when the press process is completed (see Figure 3). This causes the pressing punch 35 to lightly contact the workpiece W that has been pressed into a U-shape, pressing the workpiece W against the die 3.

The side cross-sectional view at this time is shown in Figure 11. As shown in the figure, the workpiece W is sandwiched and restrained between the pressure punch 35 and the die 3 at the rear part Wr. However, at the front part Wf, although it is seated on the die 3, a clearance L is formed between the pressure punch 35 and the front part Wf, and it is not in contact with the pressure punch 35. As a result, an additional thickness is formed between the front part Wf and the pressure punch 35.

The second step is completed when the workpiece W is clamped between the pressing punch 35 and the die 3 in this manner.

Next, the third step is started. At this time, as shown in FIG. 7, the upper die support member 9 is further lowered. This lowering is performed consecutively to the previous lowering shown in FIG. 6. Because the pressure punch 35 has already hit the workpiece W, the pressure punch 35 and punch holder 6 cannot be lowered. Therefore, the telescopic mechanism 10 contracts, allowing the upper die support member 9 to be lowered further.

At this time, as shown in FIG. 13, a downward load F3 that exceeds the contraction start load A0 is applied to the upper die support member 9. This causes the expansion/contraction mechanism 10 to contract by the contraction amount B3 (>0).

Now, when the upper die support member 9 is further lowered, the pressing member 29 also descends and comes into contact with the locking member 21, pressing the locking member 21 downward. This downward force is converted into a force directed inward in the left-right direction through the inclined cam surfaces 30, 31. As a result, the locking member 21 slides horizontally inward in the left-right direction against the biasing force of the return spring 32. Then, the lower die side engaging protrusion 24 and the upper die side engaging protrusion 25 of the locking member 21 simultaneously engage with the lower die side protrusion 22 and the upper die side protrusion 23, respectively, that is, the lower die side protrusion 22 and the upper die side protrusion 23 are sandwiched together from above and below. This locks the die holder 4 and the punch holder 6 so that they do not separate from each other, and the third step is completed.

When engaged, the upper surface of the lower die side engagement protrusion 24 of the locking member 21 slides into contact with the lower surface of the lower die side protrusion 22 of the die holder 4. These upper and lower surfaces are horizontal planes, i.e., planes parallel to the left-right direction.

Similarly, when engaged, the lower surface of the upper die side engagement protrusion 25 of the locking member 21 slides into contact with the upper surface of the upper die side protrusion 23 of the punch holder 6. These lower and upper surfaces are horizontal planes, i.e., planes parallel to the left-right direction.

When the pressing member 29 descends, the outer wall 28 slides into contact with the pressing member 29 to guide the descent of the pressing member 29 and support the pressing member 29 from the outside in the left-right direction.

Next, the fourth step is started. At this time, as shown in FIG. 8 and FIG. 12, the thickening punch 36 is inserted horizontally from the front into the gap G between the front part 35F of the pressing punch 35 and the die 3. As a result, the entire front end surface of the workpiece W is pressed backward by the thickening punch 36, the material of the workpiece W is deformed to fill the clearance L, and the front part Wf of the workpiece W is thickened. In particular, the material of the workpiece W flows toward the pressing punch 35, and the flow is restricted when it comes into contact with the pressing punch 35. Therefore, the front part Wf of the workpiece W is thickened in the inner diameter direction and deformed to a larger thickness t2. Since the rise of the material is restricted by the upper end pressing part 45, the height position of the upper end surface of the front part Wf of the workpiece W is aligned to the same height position as the upper end surface of the rear part Wr.

The rear end surface of the workpiece W is abutted against the rear wall 34 of the die 3. This prevents the workpiece W from moving backward or shifting out of position during thickening processing.

During thickening processing, an upward forming reaction force F4 is applied to the pressure punch 35. This forming reaction force F4 is a force that raises the pressure punch 35, moving the upper die 2 away from the lower die 1 and expanding the clearance L. If the locking mechanism 20 is not locked and the forming reaction force F4 exceeds the downward load F3 applied to the upper die support member 9, the pressure punch 35 actually rises and the clearance L expands. If this happens, the dimensions and shape of the clearance L will change, and there is a risk that the desired thickening shape will not be obtained.

Therefore, in this embodiment, the lower die 1 and the upper die 2 are locked by the locking mechanism 20. This prevents the lower die 1 and the upper die 2 from moving apart during the thickening process, making it possible to reliably obtain the desired thickening shape.

When the forming reaction force F4 is greater than the downward load F3, the locking mechanism 20 applies a downward assist load or lock load F5 equal to the difference between them (F4-F3) to the upper die 2, suppressing the rise of the pressing punch 35. The larger the difference (F4-F3), the greater the lock load F5 naturally becomes, so even if the forming reaction force F4 increases, the rise of the pressing punch 35 can be suppressed without changing the magnitude of the downward load F3.

Therefore, even with a relatively weak and small press machine, the thickness increase process can be carried out without any problems. This is not only suitable for mass production, but is also ideal for producing a small number of prototypes with limited equipment.

When the forming reaction force F4 is equal to or less than the downward load F3, no assistance is required, so the lock load F5 is zero.

It is preferable to determine in advance the difference (F4-F3) between the actually generated molding reaction force F4 and the downward load F3, i.e. the required locking load F5, and set the specifications of the locking mechanism 20 based on this magnitude. For example, the greater the required locking load F5, the stronger the structure of the locking member 21 needs to be. Therefore, as shown in Figure 8, it is preferable to increase the thicknesses t3 and t4 and the front-to-rear length of the lower mold side engaging protrusion 24 and the upper mold side engaging protrusion 25 of the locking member 21. It is also preferable to use a stronger material for the locking member 21.

When the thickening process is completed in this manner, the thickening punch 36 is pulled forward. Then, as shown in FIG. 9, the upper die support member 9 is raised to the top dead center. This reverses the procedure described above, unlocking the locking mechanism 20, extending the telescopic mechanism 10, and pulling the holding punch 35 out of the die 3. The pressing member 29 is separated from the locking member 21, which is pulled by the return spring 32 back to its original release position.

Finally, the pad 8 is raised, and the workpiece W after the thickening process is pushed off from the die 3 and raised. This makes it possible to remove the workpiece W, and the fourth step is completed.

As described above, according to this embodiment, the locking mechanism 20 is provided, so that the upper die 2 is locked to the lower die 1 during thickening processing, and the rise of the upper die 2 is suppressed, making it possible to reliably obtain the desired thickening shape. Moreover, even if the molding reaction force F4 during thickening processing is greater than the downward load F3 applied by the press machine M, the locking mechanism 20 can generate a locking load F5 that compensates for the difference (F4-F3). Therefore, thickening processing can be performed without any problems even with a relatively weak and small press machine.

In addition, in this embodiment, the locking member 21 moves horizontally and simultaneously engages with the lower die side engaging portion and the upper die side engaging portion, thereby locking the lower die 1 and the upper die 2. This allows the locking member 21 to have a strong structure independent of the lower die 1 and the upper die 2, and ensures locking even when the molding reaction force F4 is high.

In particular, the locking member 21's engaging protrusions 24, 25 clamp the lower mold side protrusion 22 and the upper mold side protrusion 23 to lock them together, ensuring a reliable locking effect.

In addition, in this embodiment, when the upper mold support member 9 descends, the pressing member 29 can press the locking member 21 toward the engagement side (inward in the left-right direction). Therefore, the descent of the upper mold support member 9 can be used to move the locking member 21 toward the engagement side, thereby locking it.

In this embodiment, the locking member 21 and the pressing member 29 are provided with inclined cam surfaces 30, 31, so that the downward force from the pressing member 29 can be smoothly converted into a force toward the engagement side (inward in the left-right direction) and transmitted to the locking member 21.

In this embodiment, a return spring 32 is provided to bias the locking member 21 toward the disengagement side, so that the locking member 21 can be normally retracted to the disengagement position, preventing the locking member 21 from interfering with work. In addition, it is convenient that the locking member 21 can be automatically retracted when the pressing member 29 rises during unlocking.

Next, we will explain the modified examples. Note that parts similar to those in the basic embodiment will be given the same reference numerals in the figures and will not be explained again. Below, we will mainly explain the differences from the basic embodiment.

As shown in FIG. 14, in this modified example, the contact or engagement surfaces between the locking member 21 and the die holder 4 and punch holder 6 are tapered.

In detail, the lower surface 37 of the lower die side protrusion 22 of the die holder 4 is an inclined surface that rises toward the outside in the left-right direction. The upper surface 38 of the lower die side engagement protrusion 24 of the locking member 21 that contacts this is also an inclined surface in the same way.

On the other hand, the upper surface 39 of the upper die side protrusion 23 of the punch holder 6 is an inclined surface that slopes downward toward the outside in the left-right direction. The lower surface 40 of the upper die side engagement protrusion 25 of the locking member 21 that contacts this is also an inclined surface in the same way.

As shown in FIG. 6, in the basic embodiment, the distance H1 between the lower surface 37 of the lower mold side convex portion 22 and the upper surface 39 of the upper mold side convex portion 23 is constant in the left-right direction. This is because the surfaces 37, 39 are horizontal and parallel. In addition, the distance H2 between the upper surface 38 of the lower mold side engaging convex portion 24 of the locking member 21 and the lower surface 40 of the upper mold side engaging convex portion 25 is also constant. This is because the surfaces 38, 40 are horizontal and parallel.

In this case, if the gap H2 becomes too large compared to the gap H1 due to dimensional variations or the like, the lock between the lower die 1 and the upper die 2 will become weak, and there is a risk that they will separate slightly during the thickening process.

On the other hand, in the case of this modified example shown in FIG. 14, the locking member 21 can be pressed by the pressing member 29, so that the locking member 21 can be moved inward in the left-right direction until the engagement surfaces come into contact or are in close contact with each other. This ensures that the lower mold 1 and the upper mold 2 are locked securely without being affected by dimensional variations, and further prevents them from separating during thickening processing.

Although the embodiments of the present disclosure have been described in detail above, there are many other possible embodiments and variations of the present disclosure.

(1) In the above embodiment, when moving from the press processing process to the thickening processing process, the punch 5 is replaced with the holding punch 35. However, without such replacement, two press machines may be equipped with the punch 5 and the holding punch 35, respectively, and the workpiece W may be moved from one press machine to the other press machine.

In this case, after pressing is performed by one press machine equipped with a punch 5, the workpiece W is moved to the other press machine equipped with a pressing punch 35, and the other press machine performs thickening processing. When mass-producing workpieces W in the final shape shown in FIG. 2(C), it is more efficient to divide the process by machine in this way. It is sufficient to equip at least the other press machine with the locking mechanism 20.

(2) The workpiece is not limited to being plate-shaped and U-shaped in cross section, and may be of any shape. For example, it may be plate-shaped and V-shaped, L-shaped, or S-shaped in cross section. Alternatively, it does not have to be plate-shaped, and the present disclosure can be applied to partial thickening of such a workpiece.

(3) The press machine may be formed by a servo press machine.

(4) In the above embodiment, as shown in FIG. 7, the lower mold side convex portion 22 and the upper mold side convex portion 23 are sandwiched from above and below by the engaging convex portions 24, 25 when locked. However, the locking method is not limited to this. For example, a pair of upper and lower engaging recesses may be provided on the locking member 21, and the lower mold side convex portion 22 and the upper mold side convex portion 23 may be inserted into these engaging recesses when locked.

(5) The lower die side engagement portion may be formed by a recess provided in the lower die. Similarly, the upper die side engagement portion may be formed by a recess provided in the upper die.

(6) In the above embodiment, as shown in FIG. 11, a clearance L is provided between the workpiece W before the thickness is increased and the upper die (pressing punch 35). However, a clearance may be provided between the workpiece and the lower die (die 3), or between the workpiece and both the lower die and the upper die.

(7) In the above embodiment, the internal pressure of the telescopic mechanism 10 is controlled or adjusted to prevent the telescopic mechanism 10 from contracting during press processing (FIG. 3) and to allow the telescopic mechanism 10 to contract when locked (FIG. 7). However, this is not limited to the above, and for example, the telescopic mechanism 10 may be mechanically locked to prevent contraction during press processing and unlocked to allow the telescopic mechanism 10 to contract when locked.

The embodiments of the present disclosure are not limited to the above-mentioned embodiments, and all modifications, applications, and equivalents encompassed within the concept of the present disclosure as defined by the claims are included in the present disclosure. Therefore, the present disclosure should not be interpreted in a limited manner, and may be applied to any other technology that falls within the scope of the concept of the present disclosure.

M Press machine 1 Lower die 2 Upper die 9 Upper die support member 10 Telescopic mechanism 20 Lock mechanism 21 Lock member 22 Lower die side convex portion 23 Upper die side convex portions 24, 25 Engagement convex portion 29 Pressing members 30, 31 Inclined cam surface 32 Return spring 36 Thickening punch

Claims (6)

The lower mold and
An upper mold that can be raised and lowered relative to the lower mold and that sandwiches a workpiece between the upper mold and the lower mold;
a thickness increasing die for horizontally pressing the workpiece sandwiched between the lower die and the upper die to increase the thickness of the workpiece;
a locking mechanism that locks the lower die and the upper die so that they do not separate from each other during thickening processing;
Equipped with
The locking mechanism includes:
A lower die side engagement portion provided on the lower die;
An upper die side engagement portion provided on the upper die;
a locking member that is provided so as to be movable in a horizontal direction and that can simultaneously engage with the lower die side engaging portion and the upper die side engaging portion;
Equipped
A press machine characterized by the above. the lower die side engaging portion is formed by a lower die side protruding portion provided on a side portion of the lower die,
the upper die side engaging portion is formed by an upper die side protruding portion provided on a side portion of the upper die,
The press machine according to claim 1 , wherein the locking member has a pair of engaging protrusions that sandwich the lower die side protrusion and the upper die side protrusion from above and below when engaged. The press machine according to claim 1 or 2 , wherein the locking mechanism includes a return spring that biases the locking member in a release direction. The press machine includes:
An upper die support member;
an extension mechanism that connects the upper mold to the upper mold support member so that the upper mold can be raised and lowered;
Equipped with
The press machine according to any one of claims 1 to 3 , wherein the locking mechanism includes a pressing member that is provided on the upper die support member and presses the locking member toward the engagement side when the upper die support member is lowered. The press machine according to claim 4 , wherein the locking mechanism includes inclined cam surfaces provided on the locking member and the pressing member, respectively, and capable of sliding contact with each other. A method for forming a workpiece using the press machine according to any one of claims 1 to 5 , comprising the steps of:
A first step of pressing the workpiece into a predetermined shape;
A second step of clamping the workpiece after press working between the lower die and the upper die;
a third step of locking the lower mold and the upper mold by the lock mechanism so that they do not separate from each other;
A fourth step of pressing the workpiece horizontally with the thickening die to thicken the workpiece;
A workpiece forming method comprising:

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