(19)
(11) EP 0 738 549 A1

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication:
23.10.1996 Bulletin 1996/43

(21) Application number: 96102762.0

(22) Date of filing: 23.02.1996
(51) International Patent Classification (IPC)6B21D 37/14
(84) Designated Contracting States:
DE ES IT

(30) Priority: 21.04.1995 JP 96370/95

(71) Applicant: Nitto Kohki Co., Ltd.
Tokyo (JP)

(72) Inventors:
  • Kishi, Katsunobu, c/o Nitto Kohki Co., Ltd.
    Tokyo (JP)
  • Saito, Masayuki, c/o Nitto Kohki Co., Ltd.
    Tokyo (JP)

(74) Representative: Hering, Hartmut, Dipl.-Ing. et al
Patentanwälte Berendt, Leyh & Hering Innere Wiener Strasse 20
81667 München
81667 München (DE)

   


(54) A hydraulically driving machine tool


(57) A hydraulically driving machine tool which can perform a plurality of machining operations without changing tooling is provided. A die set holder (6) is rotated in a state in which die sets (20) are fixed to the die set holder (6) rotatably mounted on a column (3), and the required die set (20) is moved to a position right under a hydraulically operating device (5). When the set screws (10) of fixing devices (9) are tightened in this state, the die set holder (6) is moved downward to be fixed to the base (1). After a workpiece (W) has been set in the die set (20) right under the hydraulically driving device (5) and the hydraulically driving device (5) has been operated, the workpiece (W) is processed at a predetermined machining operation. After the machining operation has been completed, the fixing devices (9) are released. The die set holder (6) is rotated again so that the die set (20) which is to be machined next is moved to the position right under the hydraulically driving device (5) and fixed thereto. Then, the machining operation is repeated.




Description


[0001] The present invention relates to a hydraulically driving machine tool which can perform a plurality of machining operations, and more particularly to a hydraulically operating machine tool which has a base, a column, a die set holder rotatably mounted on the column and adapted to fixedly hold a plurality of die sets, a frame and a hydraulically driving device fixed to the frame which are arranged in such a way that a selected one of the die sets is brought to a single working station right under the hydraulically driving device by rotating the die set holder and can be fixed onto the base, whereby a plurality of workpieces can be machined in required different manners at the single working station as the hydraulically driving device is operated.

[0002] Conventional hydraulically driving machine tools, each of which can perform a plurality of machining operations, are disclosed in Japanese Unexamined Utility Model Application Publication No. 54-163147 and Japanese Unexamined Utility Model Application No. 2-114132, for example.

[0003] The machine tool disclosed in Unexamined Utility Model Application Publication No. 54-163147 includes a main body having a hydraulically operated ram and a moving body operated integrally therewith. The main body is provided with a cutting device, and the moving body is provided with a notching device and a bending device so that a plurality of machining operations can be performed by a single machine tool. The machine tool disclosed in Unexamined Utility Model Application Publication No. 2-114132 is adapted to detachably mount various dies on the base of the machine tool so that required die sets are attached to the machine tool to perform required machining operations.

[0004] In the former machine tool, however, such machining devices as the cutting device, the notching device and the bending device are moved simultaneously as the ram is operated. Thus, these machining devices must be surrounded by covers for safety, increasing the cost of products. Further, this machine tool is encountered with a problem in that an operator must move to the working position in front of the machining device with which the required machining operation is to be performed in order to perform the required machining operation, resulting in poor operation efficiency.

[0005] With the latter machine tool, the die set must be changed every time the kind of the machining operation is altered. Thus, it takes a long time to change the die sets, and thus the changing operation is very troublesome.

[0006] The object of the present invention is to provide a hydraulically driving machine tool in which various die sets each used for a specific machining operation is removably fixed to a respective die set holder and workpieces can be machined according to the various contents of machining operations at a single working station of the machine tool so that a small machine tool which is operated at a high efficiency can be manufactured at a low cost.

[0007] In order to achieve the object of the present invention, the present invention provides a hydraulically driving machine tool comprising a base, a frame having a lower end fixed onto the base and an upper end, a plurality of die set stations at which a plurality of die sets for holding and machining workpieces to be machined differently from each other are provided and a hydraulically driving device mounted on the upper portion of the frame, for operating the die sets so as to machine the workpiece, wherein a machining station is provided on the base and right under the hydraulically driving device and a die set holder at required positions of which the die set stations are provided is slidably mounted on the upper surface of the base in such a manner that the die sets held at the corresponding die set stations are moved to the machining station on the base to be positioned thereto.

[0008] In the hydraulically driving machine tool according to the present invention, the die set holder for fixedly holding a plurality of die sets is rotatably mounted on the column of the machine tool, the required die set is moved to the working station by rotating the die set holder and fixed onto the base, and the die set is operated by the hydraulically driving device to perform the predetermined machining operation on the corresponding workpiece. This provides a hydraulically driving machine tool having a simpler and less expensive structure than the conventional machine tool in which the cutting device, the notching device and the bending device are moved simultaneously by the operation of the ram. With the conventional machine tool, the operator must move to the machining station at which the next machining is to be performed. On the contrary, various machining operations can be performed only at one machining station in the machine tool of the present invention. Thus, the invented machine tool has excellent operativeness and exhibits a technical effect in that the die sets can be changed simply when the machining operation is required to be changed.

Brief Description of the Drawings



[0009] 

Fig. 1 is a lateral side view of a hydraulically driving machine tool according to one embodiment of the present invention;

Fig. 2 is a plan view of the hydraulically driving machine tool shown in Fig. 1;

Fig. 3 is a side view of a holding device used on the machine tool as shown in Figs. 1 and 2 together with a cross sectional view of the portion of the machine tool related to the holding device;

Fig. 4 is a front view of the hydraulically driving machine as shown in Figs. 1 and 2;

Fig. 5 is a bottom view of a die set holder used on the machine tool as shown in Figs. 1 and 2;

Fig. 6 is a lateral side view of the die set holder shown in Fig. 5, with a half portion cross-sectioned;

Fig. 7 is a plan view of the die set as shown in Fig. 5;

Fig. 8 is a lateral side view of the die set as shown in Fig. 5; and

Fig. 9 is a cross sectional view of the portion of the hydraulically driving machine tool showing the hydraulically driving device and a die set at a machining station on the base of the hydraulically operating apparatus.



[0010] A hydraulically driving machine tool according to the present invention includes sections comprising a base, a frame, a column, a die set holder, a die set and a hydraulically driving device. The general structure and operation of an electrically driving machine tool according to one embodiment of the present invention will be described with reference to Figs. 1 to 4, and then the sections of the hydraulically driving machine tool will be described in detail.

[0011] As shown in Fig. 1, a frame 2 has an upper portion 2e bent at its intermediate portion and extending therefrom substantially in parallel with the upper surface 1a of a base 1 and has a lower end fixed to one end portion of the upper surface 1a of the base 1 by means of bolts 2c. On the substantially central portion of the base 1 is provided an upright column 3 disposed between the base 1 and the upper portion 2e of the frame 2. The upper portion of the column 3 is fixed to the base 1 by threadably engaging a male set screw 3b formed on the lower end of the column 3 with a female set screw 1b formed in the base 1, and lower portion of the column 3 is fixed to the upper portion 2e of the frame 2 by means of a male set screw 3c formed on the upper end portion of the column 3 and a nut 4 threadably engaging the male set screw 3c. The nut 4 is prevented from being loosened by means of a locking screw 4a.

[0012] A hydraulically driving device 5 is detachably mounted in the free end part of the upper portion 2e of the frame 2. As shown in Fig. 2, a die set holder 6 having radially extending horizontal arms 61, 62 and 63 forming a star shape in total is provided so as to be rotatable around the column 3. A die set 20 is provided in a space between each pair of adjacent arms and fixed to the adjacent arms. The spaces between the respective adjacent arms 61 and 62, 62 and 63, and 63 and 61 are hereinafter referred to as "die set stations S1, S2 and S3".

[0013] In a free state, the die set holder 6 is lifted slightly from the upper surface of the base 1 by means of a compression coil spring 8 disposed between the base 1 and the die holder 6.

[0014] A vertical groove 7 is formed in the front end portion of each of the arms 61, 62 and 63 of the die set holder 6. After holding devices 9 have been erected and received by the grooves 7 in the corresponding arms 61, 62 and 63 of the die set holder 6, the die set holder 6 can be firmly connected to the base 1 by tightening set screws 10 each forming a fixed position determining device. The fixed positioning determining device is not limited to the set screws 10 but may be a clamping device or other suitable fixing means. A washer 30 and a dust seal 31 are provided in the upper end of the central portion of the central hole of the die holder 6.

[0015] Die sets 20 (only one shown in Fig. 1) performing different machining operations are mounted at the corresponding die set stations S1, S2 and S3 and can be fixed to the arms at both sides of the die set stations S1, S2 and S3 by means of screws (not shown). The die set holder 6 takes a slightly floating state over the base 1 by the urging force of the compression coil spring 8 when the die set holder 6 is not fixed to the base 1 by means of the holding devices 9, i.e., when the die set holder 6 is in the free state so that the die set holder 6 can be easily rotated around the column 3 even if the heavy die sets 20 are attached to the die set holder 6.

[0016] A machining station P is defined right under the hydraulically driving device 5. When the die set holder 6 is rotated and the selected die set 20 arrives at the machining station P, the positions of the grooves 7 of the arms 61, 62 and 63 of the die set holder 6 coincide with the positions of the corresponding holding devices 6. After the holding devices 9 have been inserted in the vertical grooves 7 in this state, the set screws 10 are tightened to fixedly position the die sets 20 at the corresponding die set stations S1, S2 and S3. As the hydraulically driving device 5 is actuated, the piston of the hydraulically driving device 5 lowers a punch in the die set 20 disposed right under the hydraulically driving device 6, and the die set 20 performs a predetermined machining operation in cooperation with a die in the die set 20 at the machining station P. In this case, a force equal to a reaction exerted on the base 1 and the frame 2 is applied to the column 3, thereby preventing the base 1 and the frame 2 from being deformed.

[0017] Next, the holding devices 9 are loosened and the die set holder 6 is rotated again to move the next die set 20 to the machining station P right under the hydraulically driving device 5. Then, the holding devices 9 are inserted in the corresponding grooves 7 of the die set holder 6 and the set screws 10 are tightened. Thus, the die set 20 which is to be machined next is positioned and fixed at the working station P. As the hydraulically driving device 5 is actuated again to lower the piston, a workpiece on the die set 20 newly set at the machining station P is machined in the similar manner as described above.

[0018] Since the machine tool according to the present invention has a plurality of die set stations, a plurality of die sets, the machining contents* of which are different from each other, can be provided on the respective die sets previously or the die sets can be easily replaced with the suitable ones when the machining operations are to be changed. The positioning of the die sets can be performed merely by fitting the holding devices into the grooves 7 in the free end portions of the arms 61, 62 and 63 of the die set holder 6.
*(machining purpose or function)

[0019] Then, the die set holder 6 is rotated around the column 3 to bring the die set 20 to which a workpiece is to be fixed to the machining station P right under the hydraulically driving device 5. The workpiece is machined in the predetermined way by actuating the hydraulically driving device 5. In this case, it is unnecessary to move the whole die set stations together because workpieces at the die set stations other than the machining station are not machined. Since, therefore, piston mechanisms for machining the workpieces at the die set stations other than the machining station are not required, the size of the hydraulically driving machine tool can be reduced in this aspect.

[0020] In this embodiment, the die set stations are defined between the adjacent arms of the die set holder 6. Since the die sets 20 at the die set stations are disposed on the upper surface of the base 1, the height of the frame 2 and the frame 2 are made lower than the case in which the die sets 20 are located on the die holder 6, by an amount equal to the height of the die set holder 6, thereby reducing the size of the hydraulically operating machine tool, too.

Structure of the Base



[0021] As shown in Figs. 1 and 2, the base 1 has a planar shape. The upper surface 1a of the base 1 forms a smooth flat surface, and a threaded insertion hole 1d in which the lower portion of the column 3 is inserted is formed in the central portion of the central portion of the base 1. In the portion of the base 1 which is under the threaded insertion hole 1d is formed the threaded female hole 1b for threadably engaging the male set screw 3b formed on the lower end of the column 3 so that the column 3 is fixed to the base 1. As shown in Figs. 2 and to 3, a pair of holding devices 9 which are fitted in the respective grooves 7 formed in the free ends of the arms 61, 62 and 63 of the die set holder 6 are provided on both side portions of the base 1 so as to be raised and lowered.

[0022] In Fig. 2, the holding devices 9 at the upper side and the lower side are shown in a standing state and a falling state (lowered state), respectively. As the set screws 10 of the holding devices 9 which are in a state engaging with the grooves 7 of the die set holder 6 as shown in Fig. 3 are tightened, the die set holder 6 is moved downward against the urging force of the compression coil spring 8, and the die set holder 6 can be firmly connected to the base 1. A depression 1f is formed in a portion of the upper surface 1a of the base 1 which is at the upper end of the threaded insertion hole 1d so as to hold the lower portion of the compression coil spring 8. The end portion of the upper surface 1a of the base 1 which is opposite to the end portion of the upper surface 1a of the base 1 to which the column 2 is fixed forms an inclined portion 1e for rejecting chips produced from a workpiece by the die sets 20.

[0023] Each holding means for fixing the die set holder 6 to the base 1 is not limited to the holding device 9 as described above, but may be a clamp or any other suitable holding means as long as it can fix the die set holder 6 to a predetermined position. The number of the holding devices can be selected according to the size or other factors of the machine tool.

Structure of the Frame



[0024] The frame 2 is provided in its lower portion with threaded holes 2d and is fixed to the base 1 by bolts 2c threadably engaging the threaded holes 2d. The frame 2 has an L-shaped configuration, and its upper portion 2e is bent at its intermediate portion so as to extend substantially in parallel with the flat upper surface 1a of the base 1. A column inserting hole 2a is formed in the portion of the upper portion 2e of the frame 2 which is disposed above the centre of the base 1. Another hole 2b for removably receiving the hydraulically driving device 5 is formed in the free end portion of the upper portion 2e of the frame 2.

Structure of the Column



[0025] The column 3 has a large diameter intermediate portion 3a. The portions of the column 3 higher and lower than the large diameter intermediate portion 3a form an shaft portion 3g for supporting the frame 2 and another shaft portion 3h for supporting the die set holder 6, respectively. The shaft portion 3h rotatably holds the die set holder 5 and is provided on its lower end with the male set screw 3b threadably engaging the threaded hole 1b in the base 1. The shaft portion 3g for supporting the frame 2 is inserted in the column inserting hole 2a and the upper end portion of the shaft portion 3g projecting upwardly from the hole 2a is formed with a screw 3c. A nut 4 is threadably engaged with the screw 3c so as to fix the frame 2 to the column 3 with the upper surface 3e of the large diameter intermediate portion 3a of the column 3 abutted against the lower surface of the upper portion 2e of the frame 2. In the nut 4 there is provided a locking mechanism comprising a slit 4b and locking screw 4a inserted therein.

[0026] The upper end portion 3f of the shaft portion 3h for supporting the die set holder 6 is formed larger than the shaft portion 3h itself so as to hold the washer 30. The fixing means for fixing the column to the base is not limited to a set screw but may be one of various fixing means.

Structure of the Die Holder



[0027] As shown in Fig. 5 showing a bottom view and Fig. 7 showing a side view with a half portion cross sectioned, the die set holder 6 has a cylindrical central portion 6e formed with a central through hole 6a in which the shaft portion 3h of the column 3 is inserted. Arms 61, 62 and 63 are arranged at the same circumferential intervals on the central portion 6e end extend horizontally and radially outward from the outer peripheral wall of the central portion 6b. Each arm is formed on both sides with threaded holes 6b opening toward the adjacent arms. A die set 20 is fixed on both sides thereof to each pair of the adjacent arms by means of screws so that each die set 20 is fixedly provided between the corresponding adjacent arms. In Fig. 5, only one die set 20 is shown which is fixed to the corresponding pairs of the arms 62 and 63. The portions between the adjacent arms 61 and 62, 62 and 63 and 63 and 61 at which the die sets 20 are provided define the die set stations S1, S2 and S3, as already described.

[0028] In the lower part of the central portion 6e of the die set holder 6 is formed a large diameter hole 6c for receiving the compression coil spring 8. As shown in Figs. 1 and 3, washers 8a and 8b are provided in depression 1f in the upper surface 1a of the base 1 and the upper end portion of the large diameter hole 6c, respectively, and the compression coil spring 8 is housed in the large diameter hole 6c with the lower end portion of the spring 8 received in the depression 1f. When the die set holder 6 is made rotatable around the central portion 6e of the column 3, that is, when the die set holder 6 is not fixed to the base 1, the die set holder 6 is raised slightly from the base 1 by the urging force of the compression coil spring 8. In this state, the die set holder 6 can be rotated around the column 3 easily because frictional force between the die set holder 6 and the base 1 is reduced. In this state, the die set holder 6 is urged downward through the washer 30 by the upper portion 3f of the shaft portion 3h of the column 3 for supporting the die set holder 6 so that the die set holder 6 is not lifted unnecessarily. A bushing 6d is fitted in the through hole 6a of the die set holder 6.

[0029] A vertical groove 7 is formed in the front end portion or the free end portion of each of the arms 61, 62 and 63. A holding device 9 is fitted in the groove 7 of the corresponding one of the arms and the set screw 10 of the holding device 9 is tightened. Thus, the die set holder 6 is firmly connected to the base 1 and the die sets 20 are set to the required positions.

Structure of the Die Sets



[0030] Figs. 7 and 8 are, respectively, a plan view and a lateral side view of a die set 20 for performing cutting operation. Die sets for performing bending operation and notching operation can also be used. These die sets have same structures as the well-known conventional ones, the detailed description thereof being omitted, and only a die set for performing cutting operation will be described.

[0031] The die set 20 as shown in Figs. 7 and 8 has legs 21 extending laterally outward and horizontally from both sides of the lower portion of the die set 20. Each die set 20 can be fixed to the die set holder 6 by fixing the legs 21 to the corresponding adjacent arms on both sides of the die set 20 by means of screws or the like. A die 22 is fixed to each die set 20, and a punch 23 for cutting a workpiece W in cooperation with the die 22 is vertically slidably provided in the die set 22 so as to cut a workpiece W in cooperation with the die set 22. As the punch 23 is lowered by the hydraulically driving device 5 with the workpiece W mounted on the die 22, the workpiece W is cut by the die 22 and the punch 23.

Structure of the Hydraulically Driving Device



[0032] As shown in Fig. 9, the hydraulically driving device 5 has a vertical cylinder 51 and a piston 52. When a hydraulic pressure is supplied to the interior of the cylinder 51 through a coupling (not shown) from a hydraulic pressure source, the piston 52 is lowered and the die set 20 is operated.

[0033] The piston 52 is slidably provided in the cylinder 51. A stop 53 for determining the lower limit of the piston 52 is provided in the lower portion of the cylinder 51. A compression coil spring 54 for returning the piston 52 to the original position is provided between the stop 53 and the piston 52.

[0034] A flange 55 is formed on the lower end of the cylinder 51, and the hydraulically driving device 5 can be fixed to the frame 2 by connecting the flange 55 to the free end portion of the frame 2 by means of bolts 56. A vent 57 is formed in the stop 53. A driving device using compressed air can be used in place of the hydraulically driving device.

[0035] The units having the above-mentioned structures as described above will be assembled together with reference to Figs. 1 and 9.

[0036] First, the die set holder 6 provided with the washer 30, the bushing 6d and the dust seal 31 are mounted on the column 3. After the washer 8b, the compression coil spring 8 and the washer 8a have been mounted on the column 3, the male set screw 3b of the lower end of the column 3 is threadably engaged with the threaded insertion hole 1d whereby the column 3 is fixed to the base 1. Next, the upper axial shaft portion 3g is fitted in the inserting hole 2a and the lower end portion of the frame 2 is fixed to the base 1 by means of bolts 2c. Then, the nut 4 is threadably mounted on the screw 3c of the upper end portion of the column 3 which extends through the upper portion 2e of the frame 2 , thereby fixing the frame 2 to the column 3. In this way, the assembly of the base 1, the frame 2 and the column 3 is completed. The hydraulically driving device 5 is fixed to the free end portion of the upper portion 2e of the so assembled frame 2 by means of the screws 56, and die sets 20 are arranged at the die set stations S1, S2 and S3 and are fixed to the corresponding arms 61, 62 and 63. In this way, the manufacture of the electrically driving machine tool is completed.

[0037] The cutting operation will be described. The required die set 20 is moved to the machining station P right under the hydraulically driving device 5 by rotating the die set holder 6. The holding devices 9 pivoted on the base 1 are raised to be fitted into the grooves 7 formed in the corresponding arms 61, 62 and 63 to be set in position. As the set screws 10 of the holding devices 9 are tightened in this state, the die set holder 6 is moved downward against the urging force of the compression coil spring 8, and the undersurface of the die set holder 6 abuts against the flat upper surface 1a of the base 1, whereby the die set holder 6 is fixedly connected to the base 1.

[0038] As a workpiece W is set in the die set 20 and then the hydraulically driving device 5 is operated, the piston 52 is lowered to descend the punch 23 of the die set 20, whereby performing the predetermined machining operation on the workpiece W (cutting operation in this case). After the machining operation has been finished, the holding devices 9 are released. The die set holder 6 is made free and is rotated. The die set 20 which is to perform the next machining operation is moved to the machining station P right under the hydraulically driving device 5 and is fixed thereto. The machining operation is repeated in the similar way to the above-mentioned cutting operation.

[0039] As mentioned above in the present invention, a plurality of die sets 20 are previously set on the die set holder 6. The die set holder 6 is rotated to bring a required die set 20 to the machining station P. Workpieces W to be machined in different ways can be processed so that the operator can perform different machining operations at only one position, i.e., without changing the machining position. The die set holder 6 may be adapted to be rotated in one direction or in the forward and reverse directions. The number of the die sets provided on the die set holder in this embodiment is three but may be more than three by increasing the number of the arms and the die set stations according to their necessity. On the other hand, two arms and two die set stations can be used. The present invention is applicable to various embodiments and modifications without being departed from the spirits and the principal features of the present invention. The embodiment as described above is an example only in all respects and should not be interpreted as being limited thereto. When, in particular, the height of the hydraulically driving machine tool need not be considered, the die set holder may be formed in a disc-like shape, a polygonal shape or other shapes and the die set stations are formed on the outer peripheral portions or the corners of the upper surface of the die set holder. Further, the die set holder may be moved linearly in one direction or in both opposite directions in place of rotational movement of the die set holder.


Claims

1. A hydraulically driving machine tool comprising a base (1) having an upper surface (1a), a frame (2) having a lower end fixed to said base (1) and an upper portion (2e), a plurality of die set stations (S1, S2, S3) at which a plurality of die sets (20) for holding and machining workpieces (W) to be worked at different machining operations from each other are provided, and a hydraulically driving device (5) provided in said upper portion (2e) of said frame (2), for operating said die sets (20),
   characterised in that
a machining station (P) is provided on said base (1) and right under said hydraulically driving device (5), and a die set holder (6) provided at required positions thereof with said die set stations (S1, S2, S3) is slidably moved on said upper surface (1a) of said base (1) to position said die sets (20) at said machining station (P).
 
2. The hydraulically driving machine tool according to claim 1, characterised in that at least one holding device (9) for fixing said die set holder (6) to said base (1) is provided on said base (1) so as to be engageable with and disengageable from said die set holder (6) when a required one of said die sets (20) is positioned at said machining station (P).
 
3. The hydraulically driving machine tool according to claim 2, characterised in that urging means (8) for lifting said die set holder (6) from said upper surface (1a) of said base (1) when said holding device (9) is disengaged from said die set holder (6) is provided between said base (1) and said die set holder (6).
 
4. The hydraulically driving machine tool according to claim 3, characterised in that said urging means comprises a compression coil spring (8).
 
5. The hydraulically driving machine tool according to claim 3 or claim 4, characterised in that said holding device (9) has one end pivoted on said base (1) so as to take a horizontal state and a vertical state, and said die set holder (6) is provided with at least one groove (7) for engaging said holding device (9) when said holding device (9) takes said vertical state and disengaging from said holding device (9) when said holding device (9) takes said horizontal state.
 
6. The hydraulically driving machine tool according to claim 5, characterised in that said holding device (9) is provided with a fixing position determining device (10) for fixing said die set holder (6) to said base (1).
 
7. The hydraulically driving machine tool according to any one of the preceding claims, characterised in that a column (3) for supporting said frame (2) is provided between said base (1) and said upper portion (2e) of said frame (2), and said die set holder (6) is provided on said column (3) so as to be rotated therearound.
 




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