Bending machine and bending method

Abstract

The bending machine (10) comprises: an upper worktable (20) which is arranged on the upper part of the main frame (16) in a manner that can move up and down and holds a punch die on the lower side; and a lower worktable (26) which is arranged on the lower part of the main frame (16) and holds a die die on the upper side. A pair of slits (30) extending symmetrically in the left and right directions are formed on the lower worktable (26), and the ends of the slits (30) on the left and right outer sides are open. Elastic components (54) are provided at the ends of the slits (30) on the left and right outer sides. The elastic components (54) are configured to be switchable between a load-bearing state for bearing a bending load acting on the lower worktable (26) and a release state in which the load-bearing state is released.

Description

Technical Field

[0001] The present invention relates to a bending machine for bending a workpiece (sheet metal) and a bending method. Background Art

[0002] A vertically movable upper table, which holds the punch (upper tool) die, is located above the main frame of the bending machine. The upper table extends in the lateral direction. A pair of lifting cylinders, separated in the lateral direction, are located above the main frame to raise and lower the upper table. Furthermore, a lower table, which holds the die (lower tool), is located below the main frame. The lower table also extends in the lateral direction.

[0003] After the workpiece is positioned relative to the punch die in the front-to-back direction, the upper table is lowered by driving a pair of lifting cylinders. The punch die and the punch die cooperate to bend the workpiece to a predetermined angle.

[0004] When bending a workpiece, the bending load (bending force) generated by the lifting cylinder acts on both ends of the upper table. However, the reaction force from the workpiece also causes the lower surface of the upper table to bend concavely, and the upper surface of the lower table to bend concavely as well. In this case, the gap (upper and lower) between the upper and lower tables is not uniform along the left-right direction. As a result, if the workpiece's bending length is slightly shorter than or roughly the same as the full length of the lower table, the bending angle along the workpiece's bending length becomes inconsistent, reducing the "longitudinal accuracy" (the degree of accuracy of the bending angle along the workpiece's bending length) of the bending process.

[0005] To prevent degradation in longitudinal accuracy during bending, a bending machine has been developed that incorporates a pair of slits in the lower worktable to control its deflection (see Patent Documents 1 and 2 below). The lower worktable is formed with a pair of slits extending in the left-right direction. The outer ends of each slit open onto the side of the lower worktable. This creates a convex curve on the upper surface of the lower worktable, minimizing the left-right variation in the gap between the upper and lower worktables, thereby preventing degradation in longitudinal accuracy.

[0006] In the bending machine disclosed in Patent Document 1, fixed blocks for adjusting the deflection of the lower table are respectively disposed within a pair of slits formed in the lower table and open at the side edges of the lower table. Furthermore, in the bending machine disclosed in Patent Document 2, coil springs for adjusting the deflection of the lower table are fixedly disposed at the open ends of a pair of slits open at the side edges of the lower table.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-228004

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2000-343125 Summary of the Invention

[0011] exist Figure 1 The bending state (bent state) of the upper and lower tables in the hemming machine disclosed in Patent Document 1 during bending processing is schematically shown (the upper and lower tables are shown separately). Figure 1 (a) represents the bending process of a medium thickness plate workpiece. Figure 1 (b) represents the bending process of thin plate workpiece. Figure 1 (c) shows bending of a thick plate workpiece. In the figure, "FF" indicates the front direction, "FR" indicates the rear direction, "L" indicates the left direction, "R" indicates the right direction, "U" indicates the upper direction, and "D" indicates the lower direction.

[0012] In the bending machine disclosed in Patent Document 1, for example, when a middle plate is bent, Figure 1 As shown in (a), the gap between the upper table T1 and the lower table T2 is adjusted by the fixed block in the slit in such a way that the gap is constant. On the other hand, when bending a thin plate, as shown in Figure 1 As shown in (b), the bending load (bending force) acting on the upper table T1 is small, resulting in less deflection in the center of the upper table T1 in the horizontal direction. Furthermore, due to the reduced bending load and the thinner plate thickness, the reaction force from the workpiece is also small. Consequently, the deflection of the lower table T2 also differs slightly from that in the case of bending a plate in the middle (only the ends of the lower table T2 deflect until the blocks fixed in the slit begin to suppress deflection). Consequently, the gap between the upper table T1 and the lower table T2 increases toward the outer sides in the horizontal direction. As a result, when the bending length is slightly shorter than, or roughly the same as, the total length of the lower table T2, the bending angle increases at the ends of the bending length and decreases at the center.

[0013] In addition, when bending thick plates, Figure 1 As shown in (c), the bending load acting on the upper table T1 is large, and the deflection of the center portion of the upper table T1 in the left-right direction is large. In addition, due to the increased bending load and the thicker plate thickness, the reaction force from the workpiece is also large. Therefore, the deflection of the lower table T2 also slightly changes from the case of bending the middle plate (the deflection below the two ends of the lower table T2 is reduced). Therefore, the closed gap between the upper table T1 and the lower table T2 becomes smaller on the outside in the left-right direction. As a result, if the bending length is slightly shorter than or approximately the same as the total length of the lower table, the bending angle at both ends in the bending length direction becomes smaller. In other words, in the bending machine disclosed in Patent Document 1, regardless of the plate thickness of the workpiece, the longitudinal accuracy of the bending process cannot be fully improved.

[0014] On the other hand, as mentioned above, the hemming machine disclosed in Patent Document 2 has a coil spring fixedly installed at the open end of the slit. In other words, the hemming machine disclosed in Patent Document 2 uses a coil spring instead of the fixed block within the slit of Patent Document 1 to adjust the deflection of the lower table. However, the hemming machine disclosed in Patent Document 2 also has the same aforementioned issues as Patent Document 1.

[0015] That is, in the hemming machines disclosed in Patent Documents 1 and 2, the longitudinal accuracy of the bending process cannot be sufficiently improved regardless of the thickness of the workpiece.

[0016] The object of the present invention is to provide a bending machine and a bending method, which can make the closing interval between the upper worktable and the lower worktable close to a roughly uniform state along the left and right direction regardless of the thickness of the workpiece when bending the workpiece.

[0017] The first embodiment of the present invention provides a bending machine, characterized in that it comprises: an upper work table, which is arranged on the upper part of the main frame in a manner that can move up and down, and holds the punch die on the lower side; a lower work table, which is arranged on the lower part of the main frame, and is formed with a pair of slits extending symmetrically in the left and right directions, and the outer ends of the slits in the left and right directions are opened, and the punch die is held on the upper side; and an elastic component, which is arranged at the outer ends of the slits in the left and right directions, and is constructed to be able to switch between a load-bearing state for bearing the bending load acting on the lower work table and a released state in which the load-bearing state is released.

[0018] A second embodiment of the present invention provides a bending method, which uses the following bending machine to bend a workpiece through the cooperation of a punch die and a die die. When bending a thin plate workpiece with a thickness of less than 1.2 mm, the elastic member is placed in the load-bearing state and the movable block is placed in the first load-bearing state as needed. The bending machine used here is the bending machine of the first embodiment described above, characterized in that it also includes a movable block arranged inside each of the slits and capable of moving in the left-right direction, the movable block having a pair of first load-bearing surfaces and a second load-bearing surface arranged in the left-right direction for bearing the bending load, and the movable block is configured to be switchable between a first load-bearing state in which the first load-bearing surface and the inner surface of the slit are vertically opposed to each other with a first gap therebetween, and a second load-bearing state in which the second load-bearing surface and the inner surface of the slit are vertically opposed to each other with a second gap therebetween that is smaller than the first gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram showing the bending state of the upper and lower worktables in the bending machine disclosed in Patent Document 1, (a) shows the case of bending a medium plate, (b) shows the case of bending a thin plate, and (c) shows the case of bending a thick plate.

[0020] Figure 2 It is a schematic front view of the hemming machine according to this embodiment.

[0021] Figure 3 Yes Figure 2 An enlarged view of part III in FIG.

[0022] Figure 4 yes Figure 3 The enlarged view of the IV portion in FIG. 1 shows a first load-bearing state of the movable block in FIG. 2 , and shows a second load-bearing state of the movable block in FIG. 3 .

[0023] Figure 5A yes Figure 4 (a) VA-VA line top view. Figure 5B yes Figure 4 (b) Top view of the VB-VB line.

[0024] Figure 6 Yes Figure 3 An enlarged view of section VI in FIG.

[0025] Figure 7 Yes Figure 6 Side view of section VII.

[0026] Figure 8 yes Figure 7The cross-sectional view taken along line VIII-VIII in FIG. 1 shows a load-bearing state of the elastic member in (a), and a released state of the elastic member in (b).

[0027] Figure 9A Yes Figure 8 (a) Top view of section IXA. Figure 9B Yes Figure 8 (b) Top view of part IXB.

[0028] Figure 10 Schematic diagrams showing the bending states of the upper and lower work tables, (a) shows the case of bending a medium plate, (b) shows the case of bending a thin plate, and (c) shows the case of bending a thick plate. DETAILED DESCRIPTION

[0029] Below, refer to Figure 2 to Figure 1 1. A hemming machine 10 according to an embodiment will be described.

[0030] like Figure 2 As shown, the bending machine 10 is a sheet metal processing machine that bends a plate-shaped workpiece (metal sheet) W by cooperating with a punch die 12 and a die die 14. The bending machine 10 also includes a main frame 16. The main frame 16 includes a pair of side plates 18 spaced apart and opposed in the left-right direction, and a plurality of connecting members (not shown) connecting the pair of side plates 18.

[0031] An upper workbench 20 extending in the left-right direction is provided on the upper part of the main frame 16 so as to be movable up and down. The upper workbench 20 holds the punch die 12 in a detachable manner via a punch holder 22 extending in the left-right direction on its lower side. A lifting cylinder 24 is provided on the upper part of each side plate 18 as a lifting actuator for lifting and lowering the upper workbench 20. A pair of lifting cylinders 24 are separated in the left-right direction. In addition, a lower workbench 26 extending in the left-right direction is provided on the lower part of the main frame 16. The lower workbench 26 is opposed to the upper workbench 20 in upper and lower positions. The lower workbench 26 holds the die die 14 in a detachable manner via a die holder 28 extending in the left-right direction on its upper side. In addition, a lifting servo motor (not shown) can be used as a lifting actuator instead of the hydraulic lifting cylinder 24.

[0032] like Figure 2As shown, a pair of slits 30 extending in the left-right direction are formed on the lower workbench 26 symmetrically with respect to the center 10c of the bending machine 10 (lower workbench 26). The ends of the slits 30 on the left-right outer sides are open to the side surfaces of the lower workbench 26. The ends of the slits 30 on the left-right inner sides are terminated at the left-right central portion of the lower workbench 26. The slits 30 facilitate the bending deformation of the left-right outer sides of the lower workbench 26. Figure 3 Only one of the pair of slits 30 will be described; the other is also symmetrically formed. The slit 30 includes, from its left-right outer side, an outer horizontal portion 30a, an outer inclined portion 30b, an inner horizontal portion 30c, and an inner inclined portion 30d. The outer horizontal portion 30a is formed to be substantially horizontal, with the height of the open end of the outer horizontal portion 30a increasing. The outer inclined portion 30b is inclined relative to the horizontal, gradually lowering toward the left-right inner side. The inner horizontal portion 30c is formed to be substantially horizontal. The inner inclined portion 30d is inclined relative to the horizontal, gradually rising toward the left-right inner side.

[0033] The slit 30 is not limited to a slit having the outer horizontal portion 30a and the outer inclined portion 30b, and the shape of the slit 30 can be modified as appropriate. For example, the inner inclined portion 30d can be omitted, or another horizontal portion (not shown) can be arranged inside the inner inclined portion 30d in the left-right direction.

[0034] A fixing block 32 is provided on the lower inner wall of the inner horizontal portion 30c of the slit 30 to support the bending load acting on the portion 26u of the lower table 26 above the slit 30. The fixing block 32 has a flat load-bearing surface 32f for supporting the aforementioned bending load. The load-bearing surface 32f is vertically opposed to the flat surface 30ca of the upper inner wall of the inner horizontal portion 30c. In this embodiment, the gap AC between the load-bearing surface 32f and the flat surface 30ca (the gap of the fixing block 32) is set to, for example, 0.1 mm.

[0035] like Figures 3 to 5B As shown, a support base 34 extending in the left-right direction is provided on the left-right outer side of the fixed block 32 on the lower inner wall of the inner horizontal portion 30c. A movable block 36 is provided on the support base 34 so as to be movable in the left-right direction via a slide rail 38. The movable block 36 supports the bending load acting on the upper portion 26u. In other words, the movable block 36 is provided on the left-right outer side of the fixed block 32 on the lower inner wall of the inner horizontal portion 30c so as to be movable in the left-right direction via the support base 34 and the slide rail 38. The slide rail 38 is disposed behind the movable block 36.

[0036] The movable block 36 has a pair of flat load-bearing surfaces (a first load-bearing surface 36f and a second load-bearing surface 36s) for bearing the bending load acting on the upper portion 26u. The height of the first load-bearing surface 36f is set to be lower than the height of the second load-bearing surface 36s. The movable block 36 is configured to be able to switch between a first load-bearing state and a second load-bearing state by moving in the left-right direction. The first load-bearing state refers to a state in which the first load-bearing surface 36f and the above-mentioned flat surface 30cb are vertically opposed (see Figure 4 (a) and Figure 5A In the first load-bearing state, a first gap BC1 (gap of the movable block 36) is formed between the first load-bearing surface 36f and the flat surface 30cb. The second load-bearing state refers to a state in which the second load-bearing surface 36s and the flat surface 30cb are vertically opposed (refer to Figure 4 (b) and Figure 5B In the second load receiving state, a second gap BC2 is formed between the second load receiving surface 36s and the flat surface 30cb.

[0037] In this embodiment, the first gap BC1 is set larger than the gap AC of the fixing block 32 (eg, 0.7 mm). The second gap BC2 is set larger than the gap AC of the fixing block 32 and smaller than the first gap BC1 (eg, 0.4 mm).

[0038] In addition, the fixed block 32 may be provided on the upper inner wall instead of the lower inner wall of the inner horizontal portion 30c. In this case, the fixed block 32 bears the bending load acting on the upper portion 26u relative to the lower workbench 26. The load-bearing surface 32f is vertically opposed to the flat surface (not shown) of the lower inner wall of the inner horizontal portion 30c. Similarly, the movable block 36 may be provided on the upper inner wall instead of the lower inner wall of the inner horizontal portion 30c. In this case, the movable block 36 bears the bending load acting on the upper portion 26u relative to the lower workbench 26. The load-bearing surfaces 36f and 36s of the movable block 36 are vertically opposed to the flat surface (not shown) of the lower inner wall of the inner horizontal portion 30c.

[0039] like Figures 4 to 5B As shown, an operating lever 40 serving as an operating member for moving the movable block 36 in the left-right direction is provided on the front face of the movable block 36. A first magnet 42 is provided on the left-right inner side of the support base 34 as a first state-maintaining portion for maintaining the movable block 36 in the first load-bearing state. The first magnet 42 is magnetizable on the side surface of the movable block 36. Similarly, a second magnet 44 is provided on the left-right outer side of the support base 34 as a second state-maintaining portion for maintaining the movable block 36 in the second load-bearing state. The second magnet 44 is magnetizable on the side surface of the movable block 36.

[0040] Alternatively, two actuators (not shown) may be used as the first state holding portion and the second state holding portion instead of the first magnet 42 and the second magnet 44. Each actuator includes a shot peening pin (not shown) that can engage with an engagement hole (not shown) formed in the movable block 36.

[0041] like Figure 3 and Figures 6 to 8 As shown, a pair of brackets 46 are fixed to the left-right outer ends of the slit 30 (outer horizontal portion 30a) via fixing bolts 48. The brackets 46 are separated in the front-to-back direction. A storage case 50 extending in the front-to-back direction is fixed to the pair of brackets 46 via mounting bolts 52. The storage case 50 is located at the left-right outer ends of the slit 30. In other words, the storage case 50 is attached to the left-to-right outer ends of the slit 30 via the pairs of brackets 46.

[0042] The storage housing 50 is provided with a plurality of elastic members 54 via a mounting shaft 56 to withstand the bending load acting on the upper portion 26u. The elastic members 54 are arranged along the front-to-back direction. In other words, the storage housing 50 accommodates the lower portions of the plurality of elastic members 54 arranged along the front-to-back direction. Each elastic member 54 is composed of a plurality of coil springs 58 stacked up and down, and is capable of elastic deformation up and down. Alternatively, a hard rubber such as polyurethane rubber may be used as the elastic member 54 in place of the plurality of coil springs 58.

[0043] On the upper side of the storage case 50, a cover member 60 is provided, covering the upper portion of the elastic member 54, so that it can be displaced vertically by a pair of fixing bolts 62 and a pair of fixing nuts 64. The cover member 60 extends in the front-to-back direction. The fixing bolts 62 are inserted through insertion holes 60h formed in the front and rear portions of the cover member 60, respectively, and their tips are threadedly engaged with threaded holes 50v formed in the front and rear portions of the storage case 50, respectively. The fixing nuts 64 are threadedly engaged with the fixing bolts 62 to secure them to the storage case 50.

[0044] like Figures 6 to 9BAs shown, a plate-shaped switching component 66 for switching the elastic component 54 to a load-bearing state and a released state is provided on the upper surface of the cover component 60. The switching component 66 can move in the left and right directions, and its movement is guided by three guide pins 68. The switching component 66 is inserted into the gap G between the upper inner wall of the left and right outer end of the slit 30 and the upper surface of the cover component 60, or removed from the gap G, according to its left and right movement. The switching component 66 switches the elastic component 54 to a load-bearing state and a released state by being inserted into and removed from the gap G. In other words, the elastic component 54 is configured to be able to switch to a load-bearing state and a released state according to the left and right movement of the switching component 66. The load-bearing state refers to a state in which the elastic component 54 bears a bending load acting on the upper part 26u (refer to Figure 8 (a) and Figure 9A The released state is a state in which the load-bearing state is released, and is a non-load-bearing state in which the elastic member 54 does not bear the bending load acting on the upper portion 26u (see Figure 8 (b) and Figure 9B ).

[0045] A chamfered portion 66c extending in the front-to-back direction is formed on the inner side of the switching member 66 in the left-right direction. A finger hole 66h for inserting the operator's fingers is formed on the outer side of the switching member 66 in the left-to-right direction. A long hole 66v extending in the left-to-right direction is formed in the switching member 66. Furthermore, a fixing screw member 70 is threadedly engaged with the upper surface of the cover member 60 to secure the switching member 66 to the cover member 60. The fixing screw member 70 is inserted through the long hole 66v. Tightening the fixing screw member 70 secures the switching member 66 to the cover member 60.

[0046] Next, the stamping action (bending method) of this embodiment is described. The bending method involved in this embodiment is a method of bending a workpiece W using a bending machine 10 through the cooperation of a punch die 12 and a die die 14. In addition, when the elastic member 54 is in the released state, usually, as the bending load increases, the upper portion 26u of the lower worktable 26 first bends downward at the two ends that are easily bent. Thereafter, the upper portion 26u contacts the fixed block 32 and then contacts the movable block 36 (the first load-bearing surface 36f or the second load-bearing surface 36s).

[0047] Table 1

[0048] Workpiece type Status of elastic components Status of movable block Medium board Release status Second load bearing state sheet Load bearing state First load bearing state thick plate Release status First load bearing state

[0049] When bending a workpiece W made of a medium plate (thickness: 1.2 mm or greater and less than 3.0 mm), as shown in Table 1, the elastic member 54 is released, and the movable block 36 is placed in the second load-bearing state. Specifically, when bending a medium plate, when the bent length of the workpiece W is sufficiently longer than the total length of the lower table 26, the switching member 66 is moved outward in the left-right direction to disengage from the gap G, releasing the elastic member 54. Furthermore, the movable block 36 is moved outward in the left-right direction to the second load-bearing state.

[0050] The elastic component 54 is provided to suppress the deflection of both ends of the lower worktable 26 during the bending process of a thin plate with a long bending length, and is not required during the bending process of a medium plate, so it is in a released state. When the medium plate is bent, since its bending load is smaller than that of a thick plate, the deflection of the upper worktable 20 is smaller than that of a thick plate. In order to adjust the deflection of the lower worktable 26 in accordance with the deflection of the upper worktable 20, the movable block 36 becomes in a second load-bearing state (second gap BC2) in such a way that the gap with the upper side portion 26u of the lower worktable 26 becomes smaller. Thus, as Figure 10 As shown in (a), the closing interval (upper and lower interval) between the upper table 20 and the lower table 26 can be made substantially uniform in the left-right direction, and the longitudinal accuracy can be improved.

[0051] Furthermore, when the intermediate plate is being bent, if the bent length of the workpiece W is sufficiently shorter than the total length of the lower table 26, the elastic member 54 is released and the movable block 36 is placed in the second load-bearing state, similar to the case where the bent length of the workpiece W is long. (The case where the bent length of the workpiece W is sufficiently short will be described in detail later for both thin and thick plates.)

[0052] When bending a thin plate (thickness: less than 1.2 mm) workpiece W, as shown in Table 1 above, the elastic member 54 is placed in a load-bearing state, and the movable block 36 is placed in a first load-bearing state, as needed. Specifically, when bending a thin plate, if the bent length of the workpiece W is slightly shorter than or approximately the same as the total length of the lower table 26, the switching member 66 is moved inward in the left-right direction to insert into the gap G, placing the elastic member 54 in the load-bearing state. Furthermore, the movable block 36 is moved inward in the left-right direction to the first load-bearing state.

[0053] The elastic component 54 is provided to suppress the deflection of both ends of the lower worktable 26 during the bending process of a thin plate with a long bending length, and is therefore placed in a load-bearing state in order to utilize the deflection. In this case, the bending load is also relatively small, so the deflection of the lower worktable 26 is small, and the movable block 36 does not participate in the bending process, so it can be either the first load-bearing state or the second load-bearing state. In this embodiment, in order to safely exclude the participation of the movable block 36, the movable block 36 is placed in a first load-bearing state with a large gap between it and the upper portion 26u of the lower worktable 26. Thus, as Figure 10 As shown in (b), the closing interval between the upper table 20 and the lower table 26 can be made substantially uniform in the left-right direction, and the vertical accuracy can be improved.

[0054] During the bending process of a thin plate with a long bending length, the deflection of the lower workbench 26 is controlled by the elastic component 54. Here, the upper part 26u of the lower workbench 26 sometimes contacts the fixed block 32 and sometimes does not contact it, depending on the bending load (the thickness of the thin plate). In addition, even for a thin plate, if the thickness changes, the bending load also changes. In this embodiment, the elastic component 54 is used to elastically support the two ends of the lower workbench 26 from below. Therefore, the deflection of the lower workbench 26 is variably adjusted according to the thickness of the plate, that is, according to a relatively small bending load, thereby improving the longitudinal accuracy.

[0055] Furthermore, even when bending a thin plate, when the bent length of the workpiece W is sufficiently shorter than the entire length of the lower table 26 , the elastic member 54 is released and the movable block 36 is placed in the second load receiving state.

[0056] When bending a thick plate workpiece W (thickness: 3 mm or greater), the elastic member 54 is released, and the movable block 36 is placed in the first load-bearing state. Specifically, when bending a thick plate, if the bent length of the workpiece W is slightly shorter than, or approximately equal to, the total length of the lower table 26, the switching member 66 is moved outward in the left-right direction to disengage from the gap G, releasing the elastic member 54. Furthermore, the movable block 36 is moved inward in the left-right direction to the first load-bearing state.

[0057] As described above, the elastic member 54 is not needed during the bending process of the thick plate, so it is in the released state. When the thick plate is bent, the bending load is greater than that of the medium plate, so the deflection of the upper workbench 20 is greater than that of the medium plate. In order to adjust the deflection of the lower workbench 26 in accordance with the deflection of the upper workbench 20, the movable block 36 becomes the first load-bearing state (first gap BC1) in such a way that the gap with the upper part 26u of the lower workbench 26 becomes larger. Thus, as Figure 10As shown in (c), the closing interval between the upper stage 20 and the lower stage 26 can be made substantially uniform in the left-right direction, and the vertical accuracy can be improved.

[0058] Furthermore, even when bending a thick plate, when the bent length of the workpiece W is sufficiently shorter than the entire length of the lower table 26 , the elastic member 54 is released and the movable block 36 is placed in the second load receiving state.

[0059] Specifically, when the workpiece's bending length is short, bending is performed at the center of the upper and lower worktables 20 and 26, eliminating the need for the elastic member 54 to suppress deflection at both ends of the lower worktable 26. Therefore, when the workpiece's bending length is short, the elastic member 54 is released for all cases involving thin, medium, and thick plates. Furthermore, when the workpiece's bending length is short, significant deflection of the lower worktable 26 is unnecessary. Therefore, when the workpiece's bending length is short, the movable block 36 is in the second load-bearing state for all cases involving thin, medium, and thick plates. As a result, the workpiece is stably bent at the center of the upper and lower worktables 20 and 26.

[0060] As described above, in this embodiment, elastic members 54 are provided at the respective ends of the left-right outer sides of the slit 30. The elastic members 54 are configured to be switchable to a load-bearing state ( Figure 8 (a)) and the released state where the load bearing state is released ( Figure 8 (b)). Therefore, by switching the elastic member 54 according to the workpiece thickness and bend length, the gap between the upper table 20 and the lower table 26 can be made substantially uniform along the left-right direction, regardless of the combination of thin, medium, and thick plates, or the length of the bend. In particular, by placing the elastic member 54 in a load-bearing state, the longitudinal accuracy of thin plates with long bends can be improved. In other words, regardless of the thickness and bend length of the workpiece W, the longitudinal accuracy of the bending process can be substantially improved.

[0061] Furthermore, in this embodiment, the movable block 36 is disposed within the slit 30. Therefore, by using the movable block to switch the gap (first and second gaps) with the inner surface of the slit when the elastic member 54 is released, the deflection of the lower table 26 can be adjusted, thereby improving the longitudinal accuracy of bending medium and thick plates with long lengths.

[0062] Furthermore, since the hemming machine 10 includes the switching member 66 that switches the elastic member 54 between the load receiving state and the released state, the elastic member 54 can be easily switched.

[0063] Here, the hemming machine 10 further includes a housing 50 that houses an elastic member 54 and a cover member 60 that covers the upper portion of the elastic member 54. The housing 50 and the cover member 60 allow the elastic member 54 to be easily replaced and attached to the hemming machine 10. This structure also allows the elastic member 54 to be easily replaced.

[0064] In addition, the cover member 60 is configured to be displaceable up and down relative to the storage case 50. Therefore, the cover member 60 and the switching member 66 arranged above the elastic member 54 can be displaced up and down according to the elastic deformation of the elastic member 54 in the load-bearing state, thereby reliably adjusting the deflection of the lower table 26.

[0065] in addition, Figure 1 and Figure 10 The deflection of the upper and lower work tables is emphasized. In fact, the downward displacement caused by the deflection of the two ends of the lower work table is several millimeters, and the thickness of the switching member 66 is also about several millimeters.

[0066] The present invention is not limited to the description of the above embodiment, and can be implemented in various forms by making appropriate changes. Furthermore, the scope of the technical solutions included in the present invention is not limited to the description of the above embodiment.

[0067] The entire contents of Japanese Patent Application No. 2020-24127 (filed on February 17, 2020) are incorporated herein by reference. While the present invention has been described above with reference to the embodiments of the present invention, the present invention is not limited to the aforementioned embodiments. The scope of the present invention is determined by the scope of the technical solution.

Claims

1. A bending machine, characterized in that: have: an upper worktable, which is provided on the upper portion of the main frame in a manner capable of moving up and down, and holds the punch die on the lower side; a lower workbench provided at the lower portion of the main frame, formed with a pair of slits extending symmetrically in the left-right direction, with the left-right outer ends of the slits being open and holding the die mold on the upper side; an elastic member provided at each end portion of the slit in the left-right direction outside and configured to be switchable between a load-bearing state in which it bears a bending load acting on the lower table during bending and a non-load-bearing state in which it does not bear the load during bending; a switching component configured to switch the elastic component between the load-bearing state and the non-load-bearing state; a storage housing provided at each end portion of the slit on the left and right outer sides and accommodating the elastic member; and a cover member disposed on the upper side of the storage housing and covering the upper portion of the elastic member; The switching member is inserted into the gap between the upper inner wall of each end portion on the left and right outer sides of the slit and the upper surface of the cover member to put the elastic member into the load-bearing state, and The switching member disengages from the gap to place the elastic member in the non-load bearing state.

2. The edge bending machine according to claim 1, characterized in that It also includes a movable block disposed inside each of the slits and movable in the left-right direction, The movable block has a pair of first and second load-bearing surfaces arranged in the left-right direction for bearing the bending load. The movable block is configured to be switchable between a first load-bearing state in which the first load-bearing surface and the inner surface of the slit are vertically opposed with a first gap therebetween and a second load-bearing state in which the second load-bearing surface and the inner surface of the slit are vertically opposed with a second gap therebetween that is smaller than the first gap.

3. The edge bending machine according to claim 1, characterized in that The cover member is configured to be vertically displaceable relative to the storage case.

4. A bending method, which uses the edge bending machine according to claim 2 to bend a workpiece through the cooperation of a punch die and a die die, wherein: When a thin plate workpiece having a thickness of less than 1.2 mm is bent, the elastic member is placed in the load receiving state and the movable block is placed in the first load receiving state as needed.

5. The bending method according to claim 4, wherein: When a workpiece made of a thick plate having a thickness of 3 mm or more is bent, the elastic member is placed in the non-load-bearing state, and the movable block is placed in the first load-bearing state.

6. The bending method according to claim 4 or 5, characterized in that: When a workpiece of a middle plate having a thickness of 1.2 mm or more and less than 3 mm is bent, the elastic member is placed in the non-load-bearing state, and the movable block is placed in the second load-bearing state.

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