Die cushion device and press machine including the same

Abstract

To provide a die cushion device which is compact, is excellent in reactivity during pressing, and can apply sufficiently high energizing pressure, and to provide a press machine equipped with the same.SOLUTION: The present invention includes a cushion pad 3 disposed on a lower side of a press section, a first biasing device that applies a first biasing pressure to the cushion pad 3, and a second biasing device 2 that applies a second biasing pressure to the cushion pad 3, wherein the first biasing device includes a first support column 11 attached to a lower surface of the cushion pad 3, a biasing mechanism 12 that is attached to the first support column 11 and exerts the first biasing pressure, and a servo motor 13 that drives the biasing mechanism 12, in the die cushion device 100, the second biasing device 2 includes a second strut 21 attached to the lower surface of the cushion pad 3 so as to be parallel to the first strut 11, and a biasing cylinder 22 attached to the second strut 21 for exerting the second biasing pressure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a die cushion device and a press machine equipped with the same, and more specifically to a die cushion device that applies an upward biasing pressure in advance so as to counteract a downward processing pressure applied by a press unit during pressing, and a press machine equipped with the same. [Background technology]

[0002] In a press machine, a die cushion device is provided below a press section that performs press working on a workpiece. The die cushion device is a device that applies an upward biasing pressure in advance to counter the downward processing pressure applied by the press unit during pressing, thereby preventing wrinkles from occurring in the workpiece during press processing.

[0003] One known example of such a die cushion device includes a plurality of small pads that receive the pressing force of the slide via cushion pins, a large pad that supports the plurality of small pads, and a biasing force generating means that raises and lowers the large pad while generating an upward biasing force in response to the pressing force. The small and large pads form a die cushion pad that is provided in an internal space within a bed on which the die cushion device is provided. The small pads rise and lower within small spaces that are partitioned by ribs provided on the bed, and the large pad rises and lowers within the internal space below the ribs (see, for example, Patent Document 1).

[0004] Also known is a die cushion device that includes a cushion pad, a support column attached to the underside of the cushion pad, an air cylinder attached to the support column and urging the cushion pad upward, an upward urging device attached to the support column and urging the cushion pad upward, and a drive source for driving the upward urging device, wherein the air cylinder exerts cushion pressure from the support column against the weight of the upper movable part, and the upward urging device exerts the remaining cushion pressure, an oil chamber filled with oil is provided between the cushion pad and the support column, the upward urging device is a rack and pinion mechanism including a rack rod connected to the lower end of the support column and a pinion shaft meshed with the rack rod, and the drive source is a servo motor (see, for example, Patent Document 2).

[0005] a die cushion pressure generation line connected to a die cushion pressure generation chamber of the hydraulic cylinder; a first system pressure line connected to a first accumulator that accumulates hydraulic fluid at a first system pressure that enables the hydraulic cylinder to lower; a lowering pressure generation line connected to a cushion pad lowering pressure generation chamber of the hydraulic cylinder; and a second system pressure line connected to a second accumulator that accumulates hydraulic fluid at a second system pressure that is lower than the first system pressure and that enables the knockout operation; and a valve disposed between the die cushion pressure generation line and the first system pressure line and operable as a main relief valve during die cushioning. and a hydraulic closed circuit including a pilot-driven logic valve and a pilot relief valve disposed between a die cushion pressure generation line and a first system pressure line for generating a pilot pressure that controls the logic valve, wherein a hydraulic fluid is sealed under pressure in the hydraulic closed circuit, and no hydraulic pump is provided for pressurizing and supplying the hydraulic fluid. The hydraulic fluid in the first system pressure line and the second system pressure line in the hydraulic closed circuit can be pressurized only by the die cushion force applied from the cushion pad via a hydraulic cylinder during one cycle of the cushion pad, which includes the die cushioning action and the knockout action (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4704047 [Patent Document 2] Patent No. 5020216 [Patent Document 3] Patent No. 6386115 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, there has been a demand for faster and larger presses to accommodate the variety of workpieces, which has led to a demand for die cushion devices that are superior in responsiveness during pressing and that have a high biasing pressure capable of withstanding high processing pressure. However, although conventional die cushion devices including the die cushion devices described in Patent Documents 1 and 2 can exert a certain amount of biasing pressure, they cannot be said to be able to apply a sufficiently high biasing pressure. Furthermore, in the die cushion device described in Patent Document 3, it is difficult to increase the speed, and it cannot be said that it has excellent responsiveness.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a die cushion device that is compact, yet has excellent responsiveness during pressing and is capable of applying a sufficiently high biasing pressure, and a press machine including the same. [Means for solving the problem]

[0009] The inventors conducted extensive research to solve the above problems, and discovered that the above problems could be solved by using a servo motor as the drive source for the first biasing device, which would provide excellent responsiveness, and by providing a second biasing device using a separate support to supplement the biasing pressure, thereby completing the present invention.

[0010] The present invention provides a die cushion device for applying an upward biasing pressure against a downward processing pressure applied by a press unit during pressing, the die cushion device including: a cushion pad disposed below the press unit; a first biasing device that applies a first biasing pressure to the cushion pad; and a second biasing device that applies a second biasing pressure to the cushion pad, wherein the first biasing device includes a first support column attached to the underside of the cushion pad, a biasing mechanism attached to the first support column for exerting the first biasing pressure, and a servo motor for driving the biasing mechanism, and the second biasing device includes a second support column attached to the underside of the cushion pad so as to be parallel to the first support column, and a biasing cylinder attached to the second support column for exerting the second biasing pressure.

[0011] The die cushion device of the present invention preferably includes a plurality of second biasing devices, the sum of the second biasing pressures of all the second biasing devices being greater than the first biasing pressure, and the first biasing pressure being greater than the second biasing pressure of one second biasing device. In the die cushion device of the present invention, the sum of the second biasing pressures of all the second biasing devices is preferably two to three times the first biasing pressure.

[0012] In the die cushion device of the present invention, it is preferable that the biasing mechanism is a rack and pinion mechanism, and the biasing cylinder is an air cylinder or a hydraulic cylinder.

[0013] The die cushion device of the present invention preferably includes a plurality of second urging devices, the second support pillars are parallel to the first support pillars, and the second urging devices are preferably arranged so as to surround the first support pillars.

[0014] In the die cushion device of the present invention, it is preferable that the first biasing device further includes a housing that houses at least the biasing mechanism and the servomotor, and the second biasing device is disposed above the housing.

[0015] The present invention is a press machine including a press section and the above-described die cushion device. In a larger press machine, a plurality of die cushion devices may be attached to one press section. [Effects of the Invention]

[0016] The die cushion device of the present invention can be provided with excellent responsiveness by using a servo motor as the drive source of the first biasing device. That is, when the cushion pad is pressed down by the downward processing pressure during pressing, the cushion pad can be quickly pushed up by the biasing pressure (hereinafter referred to as "responsiveness"). This enables the die cushion device to accommodate higher speeds in press processing.

[0017] Here, in the die cushion device, since the first support pillar is not provided with a biasing cylinder, the responsiveness of the servo motor can be ensured. Note that although the responsiveness of the biasing cylinder provided on the second support pillar is inferior, it follows the responsiveness of the servo motor of the first biasing device, and therefore has excellent responsiveness.

[0018] In addition, the die cushion device includes a first biasing device that applies a first biasing pressure against the processing pressure, and a second biasing device that uses another support pillar that applies a second biasing pressure that supplements the first biasing pressure. Therefore, it is possible to apply a sufficiently high biasing pressure. Incidentally, if there is only one support pillar, there is a limit to how much the biasing pressure can be increased.

[0019] Furthermore, since the second biasing device exerts the second biasing pressure separately from the first biasing device, the moment of inertia associated with the weight of the cushion pad is reduced, and the responsiveness of the servo motor of the first biasing device is further improved. Furthermore, since the first support pillar and the second support pillar are parallel to each other, the biasing pressure of each pillar can be accurately transmitted upward. Furthermore, since a biasing cylinder is used as the second biasing device, there are advantages in that it does not require as much space and does not generate as much noise as when multiple servo motors are provided. Furthermore, by increasing the number of second biasing devices capable of exerting the second biasing pressure and increasing the number of axes, it becomes possible to finely adjust the location where the biasing pressure is applied to the cushion pad, thereby improving the molding quality of the processed product.

[0020] The die cushion device of the present invention has a plurality of second urging devices, and the first urging pressure is greater than the second urging pressure of one second urging device, so that the second urging device itself can be made compact. Furthermore, because it is compact, it can be appropriately arranged in a location where it is desired to supplement the biasing pressure in the processing pressure which varies depending on the shape of the mold. In this case, by making the first biasing pressure greater than the second biasing pressure in one second biasing device, the second biasing device can be made sufficiently compact.

[0021] In this case, by making the sum of the second biasing pressures in all the second biasing devices (hereinafter referred to as the "total second biasing pressure" for convenience) greater than the first biasing pressure, it becomes possible to apply biasing pressure to the entire cushion pad in a balanced manner. Furthermore, the load on the servo motor is reduced, which further improves responsiveness. In this case, by making the total second biasing pressure two to three times larger than the first biasing pressure, the biasing pressure can be applied to the entire cushion pad in a more balanced manner, and the responsiveness is also improved.

[0022] In the die cushion device of the present invention, by employing a rack and pinion mechanism as the biasing mechanism, the first biasing device can handle a larger load (processing pressure) and is also excellent in quietness during operation and high-speed operation. Furthermore, by employing an air cylinder or a hydraulic cylinder as the biasing cylinder, the second biasing device has the advantage of being inexpensive and easy to install.

[0023] The die cushion device of the present invention has a plurality of second biasing devices, which are arranged to surround the first support pillar, thereby making it possible to apply the second biasing pressure in a well-balanced manner and to arrange a larger number of second biasing devices in a compact manner.

[0024] In the die cushion device of the present invention, by arranging the second biasing device above the housing, the die cushion device itself can be made more compact. Furthermore, by placing the second support on the housing, the length of the second support can be minimized, which means that the weight load imposed by the second support can be reduced.

[0025] The press machine of the present invention is equipped with the die cushion device described above, which allows for faster press working and a larger press machine (larger load capacity), thereby enabling efficient press working of various workpieces. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram illustrating an outline of a die cushion device according to this embodiment. [Figure 2] FIG. 2 is a perspective view showing the die cushion device shown in FIG. [Figure 3] FIG. 3 is a schematic diagram showing an outline of the press machine according to this embodiment. [Figure 4] FIG. 4 is an explanatory diagram for explaining the operation of the press machine shown in FIG. [Figure 5] FIG. 5 is a schematic diagram showing an outline of a press machine according to another embodiment. [Figure 6] FIG. 6 is an explanatory diagram for explaining the arrangement position of the second biasing device in the press machine shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0028] The die cushion device according to the present invention is disposed below the press unit and applies an upward biasing pressure to the press unit in advance via a cushion pad to counteract the downward processing pressure applied by the press unit during pressing. Here, in this specification, the term "processing pressure" refers to the pressure applied to the cushion pad based on the downward load during pressing, and the term "urging pressure" refers to the pressure that urges the cushion pad upward against the processing pressure. For convenience, the biasing pressure by the first biasing device will be referred to as the "first biasing pressure," and the biasing pressure by the second biasing device will be referred to as the "second biasing pressure." Furthermore, when a plurality of second biasing devices are provided, the sum of the second biasing pressures of the second biasing devices is referred to as the "total second biasing pressure."

[0029] First, an embodiment of a die cushion device according to the present invention will be described. FIG. 1 is a schematic diagram illustrating an outline of a die cushion device according to this embodiment. As shown in FIG. 1, the die cushion device 100 includes a cushion pad 3 arranged below the press section 5 (see FIG. 3), a first biasing device 1 that applies a first biasing pressure to the cushion pad 3, and a second biasing device 2 that applies a second biasing pressure to the cushion pad 3. Furthermore, the die cushion device 100 has a first biasing device 1 and a second biasing device 2 that are separate from each other, and includes a plurality of second biasing devices 2.

[0030] In the die cushion device 100, a first upward biasing pressure is applied to the cushion pad 3 by the first biasing device 1, and a total second upward biasing pressure is applied by the multiple second biasing devices 2. That is, the biasing pressure applied by the die cushion device 100 is the sum of the first biasing pressure and the total second biasing pressure.

[0031] The die cushion device 100 is equipped with a plurality of second urging devices 2 that use separate supports in addition to the first urging devices 1, and is therefore capable of applying a sufficiently high urging pressure. In other words, it is possible to accommodate a large press machine. On the other hand, if the press machine is not enlarged, the biasing pressure borne by the first biasing device 1 is reduced, making it possible to downsize the first biasing device 1 and reduce energy load, noise, etc. Also, the life of the first biasing device 1 can be extended.

[0032] The cushion pad 3 is box-shaped with an open bottom, and is located at the top of the die cushion device 100 (see FIG. 2). The cushion pad 3 has an upper surface that abuts against the cushion pins 51 of the press unit 5, and is movable up and down in conjunction with the up and down movement of the slide 56 of the press unit 5 (see FIG. 4). The cushion pad 3 has a plurality of oil chambers 4 on its lower surface, and the first urging device 1 and a plurality of second urging devices 2 are attached to the oil chambers 4. The oil chamber 4 can be provided at any position. That is, when the first biasing device and the second biasing device 2 are disposed at appropriate positions to efficiently exert biasing pressure, the oil chamber 4 can be provided correspondingly.

[0033] In the cushion pad 3, the oil chamber 4 is box-shaped with an opening at approximately the center of the bottom wall, and the internal space is filled with oil. The first support 11 or the second support 21 is attached to the opening of the bottom wall, thereby sealing the space and the opening. Therefore, the processing pressure during pressing is transmitted to the first support column 11 and the second support column 21 via the oil in the oil chamber 4.

[0034] In the die cushion device 100, by providing the oil chamber 4, the downward processing pressure during pressing is transmitted via oil, and the processing pressure can be accurately transmitted to the first support column 11 and the second support column 21. In addition, the oil in the oil chamber 4 also functions as a buffer material, which can mitigate the propagation of excessive processing pressure due to the overload that occurs the moment the cushion pad 3 begins to accelerate due to the processing pressure during pressing. Since the plurality of oil chambers 4 all have the same structure, a description of the other oil chambers 4 will be omitted.

[0035] The first biasing device 1 has a first support pillar 11 attached to the oil chamber 4 on the underside of the cushion pad 3, a biasing mechanism 12 attached to the first support pillar 11 and for exerting a first biasing pressure, a servo motor 13 for driving the biasing mechanism 12, a reducer 14 attached to the servo motor, and a housing 15 that houses at least the biasing mechanism 12 and the servo motor 13. In the first biasing device 1 , the servo motor 13 drives the biasing mechanism 12 , whereby a first biasing pressure is transmitted to the cushion pad 3 via the first support column 11 .

[0036] The first support pillar 11 is in the form of a cylindrical rod, and its upper end is attached to the oil chamber 4. At this time, the shape of the upper end of the first support column 11 is a spherical seat, so even if the cushion pad 3 is tilted due to an eccentric arrangement of the mold, etc., it is possible to transmit the processing pressure in the length direction of the first support column 11.

[0037] On the other hand, the first support column 11 has a biasing mechanism 12 attached to its lower end. In the die cushion device 100, a linear motion mechanism is preferably used as the biasing mechanism 12 because the cushion pad 3 moves up and down, and specifically, a ball screw, a rack and pinion mechanism, etc. can be used. Among these, it is preferable to use a rack and pinion mechanism as the biasing mechanism 12. In this case, the first biasing device 1 (rack and pinion mechanism) can handle a larger load (processing pressure) than the other biasing mechanisms 12, and is also superior in terms of high-speed operation.

[0038] In the die cushion device 100, a rack and pinion device is used as the biasing mechanism 12. In the die cushion device 100, the rack and pinion mechanism includes a rack rod 12a and a pinion shaft 12b that meshes with the rack rod 12a. The rack rod 12a is connected to the lower end of the first support rod 11 so as to be integral with it, and moves up and down together with the first support rod 11. The pinion shaft 12 b is meshed with the rack shaft 12 a and is connected to a servo motor 13 .

[0039] In the first biasing device 1, a servo motor 13 is employed as a drive source. Furthermore, a reducer 14 may be attached to the servo motor 13. In this case, it becomes possible to appropriately convert the rotation speed or rotation torque of the servo motor 13. Furthermore, by using the reducer 14 and appropriately selecting the reduction ratio, the motor shaft torque can be reduced.

[0040] The first biasing device 1 employs the servo motor 13, and therefore has excellent responsiveness. Furthermore, in the first biasing device 1, since the first support column 11 is not provided with a biasing cylinder or the like, the reaction performance of the servo motor 13 can be further ensured. Furthermore, by making the reaction of the operations of all the second biasing devices 2 follow the reaction of the servo motors of the first biasing devices, the die cushion device 100 as a whole can be made to have excellent reactivity. As a result, the die cushion device 100 can accommodate higher speeds in press working.

[0041] The housing 15 accommodates at least the biasing mechanism 12 and the servo motor 13 . Since the servo motor 13 is generally huge, the housing 15 has an area substantially equal to that of the cushion pad 3 when viewed from above. In the die cushion device 100, by providing the housing 15, it is possible to reduce the noise generated by the servo motor 13 and ensure safety. Furthermore, by disposing the urging cylinder 22 on the upper surface of the upper wall of the housing 15, it is possible to also function as a base for the urging cylinder 22.

[0042] The second biasing device 2 has a second support pillar 21 attached to the oil chamber 4 on the underside of the cushion pad 3, and a biasing cylinder 22 attached to the second support pillar 21 for exerting a second biasing pressure. In the second biasing device 2, the second biasing pressure is transmitted to the cushion pad 3 via the second support pillar 21 by driving the biasing cylinder 22. It should be noted that the plurality of second biasing devices 2 all have the same structure, and therefore a description of the other second biasing devices 2 will be omitted.

[0043] FIG. 2 is a perspective view showing the die cushion device shown in FIG. As shown in FIG. 2, in the die cushion device 100, four second biasing devices 2 are arranged on the upper surface of the upper wall portion of the housing 15 so as to surround the first support pillar 11. In addition, in the four second biasing devices 2, the biasing cylinders 22 are attached and fixed to the upper wall of the housing 15 with fasteners such as bolts. The four second biasing devices 2 are arranged at equal intervals from one another and at the same intervals from the first support posts 11.

[0044] In this way, in the die cushion device 100, the second support columns 21 are arranged so as to surround the first support columns 11, so that a total second biasing pressure can be applied in a well-balanced manner. Furthermore, by attaching the second biasing device 2 (biasing cylinder 22) to the upper wall of the housing 15, a separate member for supporting the second biasing device 2 becomes unnecessary. Furthermore, by using the space around the first support column 11 above the housing 15 to arrange the second biasing device 2, the die cushion device 100 can be made compact.

[0045] Returning to FIG. 1, the second support pillar 21 is a cylindrical rod and is parallel to the first support pillar 11. Therefore, the biasing pressure of each can be accurately transmitted upward. Furthermore, the second support pillar 21 has a smaller diameter than the first support pillar 11, and as described above, the second biasing device 2 is disposed above the housing 15, so the length of the second support pillar 21 is shorter. Therefore, the weight load of the second biasing device 2 due to the second support pillar 21 is reduced compared to the case of the first support pillar 11.

[0046] The upper end of the second support pillar 21 is attached to the oil chamber 4 . At this time, the shape of the upper end of the second support column 21 is a spherical seat, so even if the cushion pad 3 is tilted due to an eccentric arrangement of the mold, etc., it is possible to transmit the processing pressure in the length direction of the second support column 21.

[0047] On the other hand, the second support column 21 has a biasing cylinder 22 attached to its lower end. In the die cushion device 100, an air cylinder, a hydraulic cylinder, an electric cylinder, or the like can be used as the biasing cylinder 22. Among these, from the viewpoints of ease of handling and versatility, it is preferable to use an air cylinder or a hydraulic cylinder as the biasing cylinder 22, and from the viewpoint of biasing pressure, it is more preferable to use a hydraulic cylinder. In this case, the second biasing cylinder 22 is highly versatile and can be obtained at low cost, and the size can be selected arbitrarily, so it can be easily installed wherever necessary.

[0048] In the die cushion device 100, a hydraulic cylinder that is small but can exert a sufficient biasing pressure is used as the biasing cylinder 22. The hydraulic cylinder is a so-called power cylinder that is driven to expand and contract by hydraulic pressure, and is a general cylinder that is made up of a cylinder, a piston, and a rod. The rod corresponds to the second support column 21.

[0049] In the die cushion device 100, a first biasing pressure from the first biasing device 1 and a total second biasing pressure from the plurality of second biasing devices 2 are applied to the cushion pad 3. In this case, it is preferable that the first biasing pressure is greater than the second biasing pressure of one second biasing device 2. In this case, it is possible to make the second urging device 2 as compact as possible. As a result, the second urging devices 2 are less likely to interfere with each other, which improves the degree of freedom in the number of second urging devices 2 and the positions at which they are arranged.

[0050] Furthermore, it is preferable that the sum of the second biasing pressures of all the second biasing devices 2 (total second biasing pressure) is greater than the first biasing pressure. In this case, it is possible to apply biasing pressure to the entire cushion pad 3 in a well-balanced manner. Furthermore, the load on the servo motor is reduced, which further improves responsiveness. Specifically, it is more preferable that the total second biasing pressure is two to three times the first biasing pressure.

[0051] In the die cushion device 100, the cushion pad 3 moves up and down in accordance with the upward and downward movement of the slide 56 of the press unit 5. That is, in the die cushion device 100, before pressing, the cushion pad 3 is located at the top dead center. At this time, the cushion pad 3 is constantly subjected to an urging pressure (the first urging pressure and the total second urging pressure). During pressing, the processing pressure momentarily exceeds the biasing pressure, so that the cushion pad 3 is pressed downward. Then, when the processing pressure is released after pressing, the cushion pad 3 returns to its original position at the top dead center due to the biasing pressure. The details of the movement of the die cushion device 100 will be described later together with the press machine.

[0052] As described above, the die cushion device 100 can apply a sufficiently high biasing pressure to the cushion pad 3, and therefore can also accommodate an increase in processing pressure. In other words, it can accommodate an increase in the size of a press machine. Furthermore, as described above, the die cushion device 100 has excellent responsiveness during pressing, so the cushion pad 3 returns quickly and can accommodate higher speeds in press working.

[0053] Next, an embodiment of a press machine according to the present invention will be described. FIG. 3 is a schematic diagram showing an outline of the press machine according to this embodiment. 3, the press machine 101 includes a press section 5 and the above-described die cushion device 100. The press section 5 is usually installed on the ground, and the die cushion device 100 is installed underground in a place called a pit.

[0054] In the press machine 101, the press section 5 includes at least a bolster 53 fixed to the ground, a lower die 55a installed on the upper surface of the bolster 53, an upper die 55b having a shape corresponding to the lower die 55a, a slide 56 on which the upper die 55b is supported, a cushion pin 51 provided on the upper surface of the cushion pad 3 and protruding upward through a hole provided in the bolster, and a blank holder 52 provided at the upper end of the cushion pin 51. The workpiece W is placed on the upper surfaces of the lower die 55b and the blank holder 52.

[0055] In the press machine 101, the slide 5 can be moved up and down by a known driving mechanism (not shown) such as a crank mechanism, a link mechanism, or a knuckle mechanism. Further, in the press machine 101, a known conveying device (not shown) such as a feeder or a robot for carrying in or out the workpiece W is arranged in the press machine 101 or in the vicinity of the press machine 101.

[0056] FIG. 4 is an explanatory diagram for explaining the operation of the press machine shown in FIG. First, the workpiece W is placed so that the center of the workpiece W is on the lower die 55a and the periphery of the workpiece W to be deformed is on the blank holder 52. As shown in FIG. 4, a first state 101A of the press machine (upper left of the drawing in FIG. 4) is a state before press working. At this time, the slide 56 is located at the top dead center within the range in which the slide 56 moves up and down, and the cushion pad 3 is located at the top dead center within the range in which the cushion pad 3 moves up and down with an applied biasing pressure (the sum of the first biasing pressure and the total second biasing pressure).

[0057] In the press working, the slide 56 and the upper die 55b are lowered. In a second state 101B of the press machine (upper right in FIG. 4), the press machine is in the process of pressing, and the upper die 55b is in contact with the workpiece W. The processing pressure has not yet been generated. Moreover, the cushion pad 3 is constantly maintained in a state in which an urging pressure (the sum of the first urging pressure and the total second urging pressure) is applied.

[0058] Next, a processing pressure (load) is applied to the workpiece W, and the workpiece W is sandwiched between the lower die 55a and the upper die 55b, whereby the workpiece W is molded into a predetermined shape and becomes a processed product. The time when the processing pressure is applied to the workpiece W is the pressing time. In a third state 101C of the press machine (bottom right of the drawing in FIG. 4), press working is in progress, and the cushion pins 51 are pressed downward as the workpiece W is deformed. In addition, the processing pressure is transmitted to the cushion pad 3 via the cushion pin 51, and since the instantaneous processing pressure is greater than the biasing pressure (the sum of the first biasing pressure and the total second biasing pressure), the cushion pad 3 is also pressed down. At this time, the slide 56 is located at the bottom dead center within the range in which the slide 56 moves up and down, and the cushion pad 3 is located at the bottom dead center within the range in which the cushion pad 3 moves up and down with an applied biasing pressure (the sum of the first biasing pressure and the total second biasing pressure) applied.

[0059] Then, the slide 56 and the upper die 55b are raised. The fourth state 101D of the press (bottom left of FIG. 4) is the state after the press working. At this time, the slide 56 returns to the top dead center within the range in which the slide 56 moves up and down, and since the processing pressure has been released, the cushion pad 3 returns to the top dead center within the range in which the cushion pad 3 moves up and down due to the biasing pressure (the sum of the first biasing pressure and the total second biasing pressure).

[0060] Then, the workpiece W machined into a desired shape is removed by a transfer device (not shown) or the like after the upper die 55b has been retracted. In this cycle, press working is continuously performed on the workpiece W.

[0061] The press machine 101 is equipped with the die cushion device 100 described above, and therefore can quickly perform the reaction of returning the cushion pad 3 to the top dead center. As a result, it is possible to speed up the press working. Furthermore, since the die cushion device 100 described above is provided, for example, by increasing the number of second biasing devices 2 and increasing the second biasing pressure, the sum of the first biasing pressure and the total second biasing pressure can be increased. As a result, it is possible to increase the size of the press machine itself (increase the load).

[0062] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0063] In the die cushion device according to this embodiment, the cushion pad 3 has a plurality of oil chambers 4 on its lower surface, but this is not essential.

[0064] In the die cushion device according to this embodiment, the first biasing device 1 is provided at approximately the center of the lower surface of the cushion pad 3, but if the die is disposed eccentrically, the first biasing device 1 may be deviated from the center.

[0065] In the die cushion device according to this embodiment, the first biasing device 1 has a housing 15 that houses the biasing mechanism 12 and the servo motor 13, but this is not essential. In this case, the second biasing device 2 is supported and fixed to a frame or the like.

[0066] In the die cushion device according to this embodiment, four second urging devices 2 are arranged on the upper surface of the upper wall portion of the housing 15 so as to surround the first support 11, but the installation positions of the second urging devices 2 and the number of the second urging devices 2 are not limited to this. Furthermore, the four second biasing devices 2 are arranged at equal intervals from one another and at the same intervals from the first support posts 11, but these intervals do not have to be constant. For example, when the mold is arranged eccentrically, the processing pressure on the cushion pad 3 is not uniform, and therefore it is preferable that the second biasing device 2 is also arranged eccentrically.

[0067] In the die cushion device, it is preferable to precisely adjust the location where the biasing pressure is applied to the cushion pad and install multiple second biasing pressure devices at appropriate positions. In this case, it is also possible to adjust the biasing pressure of each second biasing device independently. This can further improve the molding quality of the processed product.

[0068] In the die cushion device according to this embodiment, the first biasing pressure and the total second biasing pressure are always applied to the cushion pad 3, but this is not limiting. For example, when pressing, the first biasing pressure and the total second biasing pressure may be applied, and when not pressing (during the operation up to pressing, the return operation after pressing, standby, etc.), the first biasing pressure or the total second biasing pressure may be applied. Also, the total second biasing pressure may be applied during pressing, and the first biasing pressure may be applied during times other than pressing. Also, the first biasing pressure may be applied during pressing, and the total second biasing pressure may be applied during times other than pressing.

[0069] In the press machine according to this embodiment, one die cushion device 100 is attached to one press section 5, but multiple die cushion devices 100 may be attached to one press section 5.

[0070] FIG. 5 is a schematic diagram illustrating a die cushion device of a press machine according to another embodiment, and FIG. 6 is an explanatory view illustrating the arrangement position of a second biasing device in the press machine shown in FIG. 5. In the press machine shown in FIG. 5, two die cushion devices 100A are attached to one press section (not shown). In such a press machine, the center of processing pressure is between adjacent die cushion devices. Therefore, as shown in FIG. 6, the second pillars 21 of the three second urging devices 2 of each die cushion device 100A are arranged to surround the first pillar 11 of the first urging device 1, but two are arranged between the adjacent die cushion devices 100A from the center of each cushion pad 3, and one is arranged near the first pillar 11 on the opposite side. [Industrial Applicability]

[0071] The die cushion device according to the present invention can be used as a device for applying an upward biasing pressure in advance to counter the downward processing pressure applied by the press unit during pressing. The die cushion device is compact, yet has excellent responsiveness during pressing and can apply a sufficiently high biasing pressure. The press machine according to the present invention can be used as a machine for pressing a workpiece into a desired shape. With this press machine, the press machine itself can be made larger, and the press processing speed can be increased. [Explanation of symbols]

[0072] 1...1st biasing device 100 Die cushion device 101 Press Machine 11...1st pillar 12...Biasing mechanism 12a···Rack 12b Pinion shaft 13. Servo motor 14...Reducer 15. Enclosure 2...Second biasing device 21...2nd pillar 22.... Actuating cylinder 3. Cushion pad 4...Oil room 5. Press Department 51···Cushion pin 52 Blank holder 53 Bolster 55a...Lower mold 55b···Upper mold 56 Slide W...Work

Claims

1. A die cushion device for applying an upward biasing pressure against a downward processing pressure applied by a press unit during pressing, a cushion pad disposed below the press unit; a first biasing device that applies a first biasing pressure to the cushion pad; a second biasing device that applies a second biasing pressure to the cushion pad; Equipped with The first biasing device is a first support pillar attached to a lower surface of the cushion pad; a biasing mechanism attached to the first support column for exerting the first biasing pressure; a servo motor for driving the biasing mechanism, The second biasing device is a second support pillar attached to a lower surface of the cushion pad so as to be parallel to the first support pillar; a biasing cylinder attached to the second support pillar for exerting the second biasing pressure.

2. The second biasing device includes a plurality of second biasing devices, a sum of the second biasing pressures in all the second biasing devices is greater than the first biasing pressure; 2. The die cushion device according to claim 1, wherein the first biasing pressure is greater than the second biasing pressure of one of the second biasing devices.

3. a total of the second biasing pressures in all of the second biasing devices is two to three times as large as the first biasing pressure.

4. the biasing mechanism is a rack and pinion mechanism, 2. The die cushion device according to claim 1, wherein the biasing cylinder is an air cylinder or a hydraulic cylinder.

5. The second biasing device includes a plurality of second biasing devices, 2. The die cushion device according to claim 1, wherein the second support pillar is parallel to the first support pillar, and the second biasing device is disposed so as to surround the first support pillar.

6. the first biasing device further includes a housing that houses at least the biasing mechanism and the servo motor; The die cushion device according to claim 1 , wherein the second biasing device is disposed above the housing.

7. The press unit; A press machine comprising: the die cushion device according to any one of claims 1 to 6.

8. 8. The press machine according to claim 7, wherein a plurality of the die cushion devices are attached to one of the press sections.

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