EP0738549B1

EP0738549B1 - A hydraulically driving machine tool

Info

Publication number: EP0738549B1
Application number: EP19960102762
Authority: EP
Inventors: Katsunobu c/o Nitto Kohki Co. Ltd. Kishi; Masayuki c/o Nitto Kohki Co. Ltd. Saito
Original assignee: Nitto Kohki Co Ltd
Current assignee: Nitto Kohki Co Ltd
Priority date: 1995-04-21
Filing date: 1996-02-23
Publication date: 1999-07-07
Anticipated expiration: 2016-02-23
Also published as: EP0738549A1; ES2133181T3; JPH08290222A; CN1147984A; DE69603119T2; JP3173317B2; DE69603119D1; CN1076992C; TW299282B

Description

The present invention relates to a hydraulically driving machine tool according to the preamble of claim 1.
A machine tool of the kind referred to above is disclosed in US-A-3 921 486. The carrier member of the machine tool moves on a bearing element which is provided between the carrier member and the bearing. During machine operations the bearing element is under large stress.
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.
According to the present invention there is provided a hydraulically driving machine tool as set out in claim 1.
The hydraulically driving machine tool of the invention has a simple and inexpensive structure. Various machining operations can be performed only at one machining station in the machine tool of the present invention and thus 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.
Preferred embodiment of the present invention are subject matters of claims 2 and 3.

Brief Description of the Drawings

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.
A hydraulically driving machine tool 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 a hydraulically 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.
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 lower 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 upper 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.
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".
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.
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.
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.
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.
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.
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.
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.
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

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.
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.
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

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

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.
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

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.
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.
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

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.
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

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.
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.
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.
The units having the above-mentioned structures as described above will be assembled together with reference to Figs. 1 and 9.
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.
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.
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.
As mentioned above, 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 embodiment as described above is an example only in all respects. 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.

Claims

A hydraulically driving machine tool comprising a base (1) having a central portion and an upper surface (1a), a frame (2) having a lower end fixed to said base (1) and an upper portion (2e) having a free end, a machining station (P) provided on a portion of said upper surface (1a) of said base (1) which is right under said free end of said upper portion (2e) of said frame (2), a die set holder (6) provided over said upper surface (1a) of said base (1) so as to rotate around said central portion of said base (1) when said die set holder (6) is not fixed to said base (1), a plurality of die sets (20) each for holding and machining a workpiece (W), said die sets (20) being arranged circumferentially around said central portion of said base (1) and removably fixed to said die set holder (6) so that said die sets (20) are brought to said machining station (P) in turn as said die set holder (6) rotates, a hydraulically driving device (5) provided in said free end of said upper portion (2e) of said frame (2), for driving said die sets (20) which have been brought to said machining station (P), and fixing means for fixing said die set holder (6) to said base (1) when respective one of said die sets (20) has been brought to said machining station (P) by rotating said die set holder (6),
characterised in that

an upright column (3) having an upper end portion and a lower end portion is provided between said base (1) and said frame (2) with said upper end portion of said upright column (3) fixed to an intermediate portion of said upper portion (2e) of said frame (2) and said lower end portion of said upright column (3) fixed to said central portion of said base (1);

a spring (8) is provided between said base (1) and said die set holder (6), for lifting said die set holder (6) from said upper surface (1a) of said base (1);

said die set holder (6) is adapted to rotate coaxially around said upright column (3) when said die set holder (6) is not fixed; and

said fixing means comprises at least one holding device (9) which is provided between said base (1) and said frame (2) and has one end pivoted on said base (1) so that said at least one holding device (9) selectively takes an upright position and a horizontal position, and at least one groove (7) which is provided in said die set holder (6) so that said holding device (9) engages said groove (7) when said holding device (9) takes said upright position and disengages from said groove (7) when said holding device (9) takes said horizontal position.
The machine tool according to claim 1, characterised in that said die set holder (6) has radially extending arms (61, 62, 63) forming a star shape and said die sets (20) are disposed between the adjacent arms (61, 62, 63) and fixed thereto.
The machine tool according to claim 2, characterised in that said groove (7) is formed vertically in the front end portion of each of said arms (61, 62, 63).