WO1998040189A1

WO1998040189A1 - Workpiece feed device for a machine tool

Info

Publication number: WO1998040189A1
Application number: PCT/EP1998/001444
Authority: WO
Inventors: Bernhard Magerl
Original assignee: Bernhard Magerl
Priority date: 1997-03-13
Filing date: 1998-03-12
Publication date: 1998-09-17
Also published as: DE29800294U1; DE19710447C2; DE19710447A1

Abstract

The invention concerns a workpiece feed device for a machine tool, said device comprising two clamping parts (1, 2) which delimit a clamping region and have plane clamping faces between which a workpiece (3a) that is to be machined on at least one side can be clamped in an axial movement. The workpiece feed device also comprises two housings (11, 12) which are displaceable towards each other on a work bench, can be secured at any mutual spacing, are each connected to one of the clamping parts and via each of which a clamping force and/or an angle switching movement can be applied to the corresponding clamping part. The workpiece feed device further comprises at least one support (4a) on which the workpiece can be moved into the clamping region such that the workpiece can be clamped between the clamping parts; the at least one support can then be moved back out of the clamping region into its starting position. Preferably, by means of a shaft and a gear unit, a drive unit that is integrated in the machine tool in fixed manner introduces the at least one support into the clamping region which is disposed with a central axis that likewise remains fixed; when the workpiece has been clamped, the drive unit returns the support to its starting position.

Description

description

Workpiece feed device for a machine tool

The invention relates to a device for workpiece feed for a machine tool.

The machine tools to be equipped with devices for workpiece feeding are mainly milling machines or machining centers with which workpieces in different machining positions are machined from several sides with different rotating tools. The workpieces that are processed on the affected machine tools have either cylindrical or polygonal cross sections or other complex shapes. The workpieces are first brought into the clamping area of the machine tool, which is delimited by two parts of a clamping device, in order to then push one of the parts between the clamping jaws of the other part with an axial movement and to be fixed there by a closing movement. Three-jaw chucks, face plates, collets and the like are used on one side, while a tailstock is generally used on the other side. A simple workpiece feed is not known for machine tools with the conventional clamping technology described because of the multi-part processes.

EP 0 547 554 B1 describes a new type of workpiece holding device in which the workpiece is clamped between two flat clamping pieces under the action of an axially directed clamping force. For this purpose, the individual workpieces are brought into the clamping area between the two clamping pieces. Suitable documents, such as those described in DE 44 23 887 Cl, can be used to align the workpiece. Another possibility is to use stops attached to the clamping pieces. However, these limit the machining length of the workpieces.

With a pipe centering device according to DE 40 37 813 AI, a feed device has become known with which individual pipe sections fed on pipe supports in the horizontal direction are picked up by the support pins of the centering device and raised in the vertical direction. In this position, the longitudinal centering of each pipe section takes place due to the oppositely synchronously moving contact arms, which is followed by a renewed placement on the pipe support and further transport to a lathe. Since the lifting movement of the pipe section from the support into the centering position in the known device takes place with all parts of the centering device and the associated gear, a stable structure and a sufficiently dimensioned drive energy must be provided because of the comparatively large moving masses. This applies in particular if short feed and discharge times are to be observed. When machining small workpieces with a low dead weight, the feed processes create a particularly unfavorable ratio to the moving total weight, combined with a disadvantageous energy balance. It is also disadvantageous that the drive of the centering device, which is also moved, requires flexible connections which are laid with increased effort and tend to wear.

The invention is therefore based on the object of providing a device for workpiece feed for a machine tool which overcomes the disadvantages of the prior art, in particular for the loading of machine tools with workpieces to be machined, a simple one that can be moved from a small number

To provide parts of existing device with which short working times can be achieved with little space and energy consumption. This object is achieved according to the invention by a device for workpiece feed for a machine tool according to claim 1.

Preferred embodiments of the device according to the invention are described in subclaims 2 to 17.

The invention is based on the idea of using the support not only for the provision of the workpiece, but also in connection with a suitable mechanism for feeding the workpiece into the clamping area. This enables the creation of a very simple device with a minimum net weight for workpiece feeding, with which short working times can be achieved with little energy expenditure.

The idea of the invention can be realized, for example, in a simple manner with a guide pin attached to the support, which is guided in the work table and is actuated by a translation rotary gear. A rack and pinion drive can be used for this

Rack section is included in a space-saving manner in the cross section of the guide pin. A motor-driven gear wheel transports the workpiece into the clamping area and the support in the opposite direction of rotation back to the starting position.

In another embodiment of the invention, the guide pin is controlled by a rotating cam, the curve shape of which, after the workpiece has been introduced into the clamping area and the shaft rotates continuously, ensures a dwell time of the support in which the workpiece is clamped. Since there is no reversal of the direction of the shaft, this drive requires a particularly simple control of the motor. A return spring can be used to safely reset the pad be provided. For the actuation of the guide pin, a crank mechanism can also be provided, the crank of which is connected to the guide pin via a coupling rod.

According to another further development of the invention, a support attached to an oscillating lever arm is proposed, with which the workpiece is moved into the clamping area by a simple pivoting movement. The lever arm is rotatably connected to a motor-operated shaft. Since the guide pin and its guidance are omitted here, this embodiment represents a particularly simple development of the invention with a minimal space requirement.

The device according to the invention in its various designs can also be used successfully in machine tools with an inclined work table which is built on a frame with a triangular cross section. In addition to an improved removal of the machining products, such a design also offers the advantage of a substantial increase in the bending stiffness against the deformations of the work table caused by large clamping forces. In addition, the clamping height of the machine tool can also be reduced in a certain range of the angle of inclination.

The supports provided according to the concept of the invention are adapted in shape and dimensions to the contours of the workpiece. One pad is sufficient for short workpieces; for larger clamping lengths, several similar supports, synchronously driven with a common shaft, can also be used.

In the event that different workpieces with different cross sections are to be machined alternately by the machine tool, provision is made according to an additional development to adjust the stroke of the support by changing the pivoting range of the shaft in such a way that starting from a uniform starting position, the clamping area in which the workpiece center axis coincides with the axis of the clamping pieces is reached. This adjustment can be carried out economically with a change in the duty cycle of the servomotor.

For production series of workpieces with different clamping lengths, it is necessary to move one of the housings for the clamping pieces on the work table. For this purpose, the housing of a support spindle is provided in most cases. The pads are set up so that they can be dismantled individually to allow movement along the work table. The device for workpiece feed according to the invention can be summarized very effectively with the control of the machining sequence for the workpiece in an overall control.

Further features and advantages of the invention result from the following description, in which exemplary embodiments according to the invention are explained in detail with the aid of schematic drawings. It shows:

Figure 1 shows a cross section through an inventive

Device for a machine tool with a stationary, horizontally aligned work table and a rack and pinion drive;

Figure 2 is a front view of the device shown in Figure 1 with a partial section of the work table;

3 shows a cross section through the device according to the invention shown in FIGS. 1 and 2 for a machine tool with an inclined work table;

Figure 4 shows a cross section through a drive of a usable in a device according to the invention Guide pin with a cam disc;

FIG. 5 shows a cross section through a drive of a guide pin that can be used in a device according to the invention with a crank drive; and

Figure 6 shows a cross section through a support on an oscillating lever arm.

Figures 1 and 2 show a section of a machining center with a possible embodiment of the device according to the invention. A workpiece 3a lies on two supports 4a of width B when it is provided, the stops 5a already ensuring the alignment required for the clamping. Each of the supports 4a is guided with a guide pin 7 in a bore in the work table 6. Each guide pin 7 is formed in its lower part as a rack 8, the teeth of which are in engagement with a gear 9. The rack 8 coincides in its remaining cross section with the cross section of the guide pin 7, so that effective guidance is maintained over the entire stroke. The shaft 10 is used for the synchronous transmission of movement to the gearwheels 9, a rotation, counterclockwise in FIG. 1, causing a uniform upward movement, see arrow A in FIG. 1, of the workpiece 3a. The upward movement A ends when the workpiece 3a is brought together with a clamping area 13 delimited by the two clamping pieces 1 and 2 -Doint line specified clamping the workpiece 3a completes. The clamping force K holds the workpiece 3a with frictional engagement between the flat clamping surfaces of the clamping pieces 1, 2 not only during the individual machining processes, but also during the angular switching movements. As can be seen from FIG. 2, the workpiece holding device according to the invention enables said plans to be used Φ

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can be retracted to provide another workpiece 3a. At the same time, the machining is started by moving a tool 19 towards the workpiece 3a.

FIG. 3 shows the use of the device according to the invention just described for a machine tool with an inclined work table 6 sloping towards the operating side. The latter is held by a support 18 with a triangular cross section, which is ribbed for stiffening. The structure and the device according to the invention are exactly the same as those described for FIGS. 1 and 2. The design of the machine tool according to FIG. 3 ensures an effective automatic outflow of the cutting products including the lubricating liquids and, due to the inclined position of the axis of the guide bolt 7, allows the tip height of the workpiece holding device to be reduced. In addition, the support 18 with its inherent rigidity, even under the action of large clamping forces, means that there is no fear of a deviation in the axes of the clamping pieces 1, 2 which would impair the dimensional accuracy of the machined workpieces.

3, as in the applications according to FIGS. 1 and 2, there is also the possibility of closing the housings 11 or 12 on the work table to take into account different lengths L of the workpieces 3a, 3b after installing or removing individual supports 4a move. In the example shown in FIG. 3, the separated guide pin 7 is provided with a collar 23 which strikes in an extension of the associated bore and thus prevents it from accidentally slipping through. The design of the guide pin 7 shown here can also be used successfully in the arrangement according to FIGS. 1 and 2.

In the case of work tables 6 and their lower-rigidity supports, such as those specified for the machine tool according to FIGS. 1 and 2, additional measures can be taken Avoidance of inadmissible dimensional deviations are provided, as described in the German patent application DE 197 01 394.5.

For a feed shown in FIGS. 1 and 2, an actuation with a cam disk 31 can also be used according to FIG Arc with the radius R takes place. For this purpose, the cam disc 31 is subdivided as follows: in section 33a for lifting the workpiece 3a into the clamping area 13, section 33b with the constant radius R in which the clamping process of the workpiece 3a takes place, and section 33c for the return of the Edition 4a, which can be supported by a spring, not shown. A particular advantage of this construction is that the motor only rotates the associated shaft 10 in one direction M, that is to say it only requires control, but no reversing means.

Another simple device for workpiece feeding with the guide pin 7 already mentioned and the support 4a connected to it is shown in FIG. The movement of the guide pin 7 is actuated by a crank mechanism, in which the crank 38, which is connected non-rotatably to the shaft 10, engages via the coupling rod 35 on the pin 36 fastened in the guide pin 7. The shaft 10 is supported in bearings 38 and transmits the oscillating movement from the drive to the crank 37. The other reference numerals are taken from the preceding figures.

A particularly simple constructive embodiment of the invention is shown in FIG. 6, in which the support 4b is connected directly to a lever arm 41 which is supported on a bearing 42. Stops 5b fix the position of the workpiece 3b in the manner already shown. That according to the position shown

significantly reduce production time and thus increase productivity. In the embodiment of the machine tool according to FIGS. 1 to 6, a motor drive mounted on the shaft end is most advantageously provided for rotating the shaft 10, the operation of which is included in the overall control.

The features of the invention disclosed in the above description, in the drawings and in the claims can be essential both individually and in any combination for realizing the invention in its various embodiments.

Reference list

Clamp

Clamping piece a, 3b workpiece a, 4b support a stop

Worktable

Guide pin

Rack

Gear 0 shaft 1 housing 2 housing 3 clamping area 5 machine frame 8 support 9 tool 0 clamping claw 3 collar 1 cam 2 roller 3 a, b, c track section 5 coupling rod 6 pin 7 crank 8 bearing 1 lever arm 2 bearing

Claims

Expectations

1. Device for workpiece feed for a machine tool, comprising two clamping pieces (1, 2) delimiting a clamping area (13), which have flat clamping surfaces, between which a workpiece (3a, 3b) to be machined at least on one side can be clamped in an axial movement, Two housings (11, 12) which can be displaced relative to one another on a work table (6) and can be locked at any spacing from one another and are each connected to one of the clamping pieces (1, 2) Clamping piece (1, 2) can be applied, and at least one support (4a, 4b) on which the workpiece (3a, 3b) can be brought into the clamping area (13) such that the workpiece (3a, 3b) between the clamping pieces ( 1, 2) and then the at least one support (4a, 4b) from the clamping area (13) can be returned to its starting position.

2. Device according to claim 1, characterized in that a stationary incorporated in the machine tool drive with the aid of a shaft (10) and a gear introduces the at least one support (4a, 4b) into the clamping area (13) which is also arranged with the central axis remaining stationary and after clamping the workpiece (3a, 3b) returns to the starting position.

3. Apparatus according to claim 1 or 2, characterized in that depending on the length of the workpiece (3a, 3b) one or more, preferably identical and synchronously operable, supports (4a, 4b) are provided side by side.

4. Device according to one of the preceding claims, characterized characterized in that each of the supports (4a, 4b) is connected to a guide pin (7) which is guided in a bore in the work table (6) of the machine tool and which cooperates with a rotary translation gear.

5. The device according to claim 4, characterized in that each guide pin (7) with a preferably incorporated within its outer contour rack (8) that with a rotatably connected to the shaft (10) gear

(9) is engaged.

6. The device according to claim 4, characterized in that each guide pin (7) by means of a coupling rod (35) to a with the shaft (10) rotatably connected crank (37) is connected.

7. The device according to claim 4, characterized in that each guide pin (7) of a circumferential, with the shaft

(10) non-rotatably connected cam disc (31) can be actuated, the inclined track sections (33a, 33c) of which control the upward and downward movement of the associated support (4a, 4b), while a concentric curved piece (33b) provides a standstill for clamping the workpiece (3a , 3b) causes.

8. The device according to claim 7, characterized in that a spring supports the return of each pad (4a, 4b) in their starting position.

9. Device according to one of claims 4 to 7, characterized in that each of the supports (4a, 4b) from its guide pin (7) detachable and the latter can be lowered from the associated gear after decoupling.

10. The device according to claim 9, characterized in that after lowering, each guide pin (7) is supported with a collar (23) on a shoulder of the hole in the work table (6).

11. Device according to one of claims 1 to 3, characterized in that each of the supports (4a, 4b) is attached to a lever arm (41) pivotable about a bearing (42).

12. The apparatus according to claim 10, characterized in that each of the lever arms (41) is rotatably connected to the shaft (10) guided in the associated bearing (42).

13. The apparatus according to claim 11, characterized in that each of the lever arms (41) in the associated bearing (42) freely rotatable and of a between the support (4a, 4b) and the bearing (42) engaging gear, preferably a rotating cam drive, can be actuated.

14. Device according to one of the preceding claims, characterized in that the work table (6) is constructed on a support (18) with a triangular cross-section with a slope falling towards the operating side of the machine tool.

15. The apparatus according to claim 14, characterized in that the inclination has an angle (α) of at least 30 degrees.

16. Device according to one of the preceding claims, characterized in that on each support (4a, 4b) stops (5a, 5b) for aligning the workpiece (3a, 3b) for clamping are attached.

17. Device according to one of the preceding claims, characterized by a device for automatic overall control for the movement of the device for workpiece feed and Machining sequence of the machine tool