US20020086628A1

US20020086628A1 - Machine tool with a manipulator

Info

Publication number: US20020086628A1
Application number: US10/045,366
Authority: US
Inventors: Pavel Blazek
Original assignee: Stama Maschinenfabrik GmbH
Current assignee: Stama Maschinenfabrik GmbH
Priority date: 1999-04-30
Filing date: 2001-10-29
Publication date: 2002-07-04
Also published as: EP1175278A1; WO2000066319A1; DE19919647C2; DE19919647A1; JP2002542954A

Abstract

A machine tool (10) is provided with a workpiece carrier (19) for clamping a workpiece (18) to be machined and with a headstock (14) in which a rotary-driven tool spindle (15) is mounted into which tools (16) can be clamped for machining the workpieces (18). Further, a device (26) is provided for removing and holding the workpiece (18) that has been finished in the workpiece carrier (19) for further machining. The device (26) comprises a manipulator (27) for positioning a gripper (28) by which a workpiece (18) is removable that has been finished in the workpiece carrier (19), and a clamping station (29) into which the gripper (28) that holds the workpiece can be inserted (FIG. 1).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a machine tool, comprising a workpiece carrier for clamping a workpiece to be machined, and a headstock in which a rotary-driven tool spindle is mounted, into which spindle tools for machining the workpieces can be clamped, as well as a device for removing and holding for further machining the workpiece that has been finished in the workpiece carrier.

2. Related Prior Art

Such a machine tool is known from EP 0 368 996 B1. The known machine tool is a moving column machine, on the machine bed whereof a clamping device for workpiece bars is arranged. The clamping device is provided with a rotary drive, so that a workpiece bar can be machined at all four longitudinal sides by means of a tool that is clamped into the tool spindle.

In longitudinal direction of the workpiece bar, on the machine bed a unit for gripping and pivoting is provided that is mounted on an own cross slide. As soon as the four longitudinal sides of the workpiece have been finished, the cross slide moves towards the workpiece and clamps same into its jaw chuck. After that, the workpiece is being cut from the bar and the cross slide is somewhat moved back. The jaw chuck is now pivoted to the top by about 180°, so that the cut side can be machined from the top by means of a milling tool.

With this machine, a machining of the front side opposing the separation side is possible only in a limited way.

In order to overcome this problem, DE 196 35 258 C1 discloses a comparable machine tool, in which, however, the clamping device is pivotable about an axis that runs transversally with respect to the longitudinal axis of the workpiece bars. In this manner, it is possible to machine the four longitudinal sides of the workpiece and its front side remote from the clamping device.

After these five sides have been machined, the workpiece is mostly cut from the rest of the workpiece bar by means of a circular saw that can be clamped into the tool spindle.

After that, the clamping device is moved again into its horizontal position, so that the unit for gripping and pivoting can advance and grip the workpiece at the front side that has now been machined. After that, the workpiece is completely cut, whereupon—as described above—also the sixth side can be machined.

It is true that the machine tool known from DE 196 35 258 C1 allows machining of six sides of a workpiece, however, many intermediate steps are necessary with the result that, on the one hand, machining workpieces is very time-consuming. Another disadvantage is that problems in accuracy may occur by transferring the workpiece into a standardized chuck, since the chuck is not adapted to the outer contour of the workpiece.

Another disadvantage with the two machine tools described insofar is that they are very large-scale in design because two exactly adjustable pivoting devices have to be provided, the first of which allowing machining of the fifth side and the second one allowing machining of the sixth side.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the present invention to improve the machine tool mentioned at the outset such that the speed and the accuracy of machining are increased in a manner that is simple in design

According to the invention, this object is achieved with the machine tool mentioned at the outset in that the device comprises a manipulator for positioning a gripper, by which gripper a workpiece is removable that has been finished in the workpiece carrier, and a clamping station into which the gripper holding the workpiece can be inserted.

The object underlying the invention is in that way completely achieved.

The inventors of the present invention have recognized, namely, that a manipulator, i.e. a kind of a robot arm, may be used for transferring the finished workpiece, although both the accuracy of positioning and the holding forces of such manipulators are not sufficient for machining by means of a milling tool with the accuracy desired. For this reason, such manipulators have, up to now, not been used for holding workpieces during machining. However, by means of the clamping station provided according to the invention, these disadvantages of the manipulator that is otherwise constructed in a very cost-effective and simple manner, can be remedied by clamping the gripper into the clamping station. This means that a clamping station arranged in a predetermined adjustment provides accuracy as well as the holding forces required, while the pure handling is done by the manipulator.

In that manner, also the different intermediate steps can be avoided that are common for a 6-sides-machining in the prior art. The manipulator grips the workpiece in any position, whereupon it can be completely cut from the workpiece bar. After that, the manipulator pivots the workpiece such as required for the next machining, and then inserts its gripper into the clamping station where it is suitably clamped.

It is preferred herein if the manipulator comprises a beam that is pivotable about a vertical axis, at which beam the gripper is pivotably mounted about a rotation axis that runs transversally with respect to the vertical axis.

It is here advantageous that the workpiece can horizontally be removed from the workpiece carrier in a simple manner. The gripper then first pivots the workpiece by 90° and moves then laterally into the clamping station where it is locked. After the fifth side has been machined in this clamping, the gripper moves out of the clamping station, turns the workpiece by 180°, and then enters the clamping station again, so that now the sixth side can be machined.

In this manner, a 6-sides-machining is possible, without a pivot drive being necessary for turning a workpiece clamped for machining by 90° such that its front side can be machined.

It is further preferred if the beam is vertically adjustable into the direction of the vertical axis.

This measure means a considerable advantage in time, since the workpieces can also be vertically removed, so that pivoting back the clamping device prior to removing the workpiece can be omitted for workpiece carriers with a pivot drive.

It is generally preferred if the clamping station comprises clamping jaws for centering and holding the gripper, which clamping jaws are adapted to an outer contour of the gripper.

By means of this measure, considerable advantages in accuracy can be achieved, since an exact centering and positioning of the gripper can be provided in a reproducible manner by means of clamping jaws that are exactly adapted to the outer contour of the gripper. By means of the contours adapted to each other, it is provided that the workpiece remains adjusted right in position even in quick chip removing machining.

It is further preferred if the gripper comprises exchangeable jaws that are adapted to an outer contour of the workpiece. This measure increases the accuracy even further, since the workpiece can be held in a considerably safer manner by adapted jaws than by standardized jaws. This measure has also advantages in design because in a transition to machining a workpiece with another geometry, merely the jaws of the gripper need to be newly adapted, all other aggregates of the machine tool remain unchanged, without reduction in accuracy or speed of machining.

It is also generally preferred if the workpiece carrier comprises a clamping device that is transversally pivotable with respect to the vertical axis, by which clamping device the workpiece can be brought into a vertical adjustment for machining of its side remote from the clamping device.

This measure already known from DE 196 35 258 C1 allows machining of five sides in one single clamping. The manipulator grips, after machining the fifth side, the vertically aligned workpiece that is, subsequently, cut from the workpiece bar. After that, the manipulator pivots to the clamping station, simultaneously turning the gripper by 180°. In this position, the gripper is clamped into the clamping station, whereupon now the sixth side of the workpiece points to the top so that it can be machined.

Further advantages can be taken from the description and the attached drawings. [0027]
It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention. [0028]

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is shown in the drawings and will be explained in more detail in the description below. In the drawings: [0029]
FIG. 1 shows a schematic side view of the new machine tool; [0030]
FIG. 2 shows a top view of the machine tool from FIG. 1, also in a schematic view; [0031]
FIG. 3 shows a representation like FIG. 2, but with a workpiece pivoted by 90°; [0032]
FIG. 4 shows a top view onto a gripper clamped in a clamping station; and [0033]
FIG. 5 shows the gripper from FIG. 4 in isolated representation. [0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, a machine tool very schematically shown and comprising a [0035] machine bed 11, is generally designated with 10.
On [0036] machine bed 11, a moving column 12 is arranged at which a headstock 14 is mounted. Headstock 14 can be positioned with reference to machine bed 11 in the three directions in space in a common manner.
In [0037] headstock 14, a tool spindle 15 is rotary-driven mounted into which tools 16 can be inserted for machining a workpiece 18 that is held in a workpiece carrier 19.
[0038] Workpiece carrier 19 comprises a clamping device 21 into which workpiece 18 is clamped. Clamping device 21 can be pivoted about a pivot axis indicated in 22 such as indicated by an arrow 23. In the clamping shown in FIG. 1, workpiece 18 is being machined at its side 24 remote from clamping device 21.
Besides of workpiece carrier [0039] 193 a device 26 for removing and holding a workpiece 18 finished in clamping device 21 is arranged on machine bed 11. This device 26 comprises a manipulator 27 that carries a gripper 28 on its outer end. Behind manipulator 27, a clamping station 29 is indicated into which gripper 28 can be clamped in a manner yet to be described.
Finally, a [0040] deposit station 31 is indicated at the right side of manipulator 27 onto which manipulator 27 lays down finished workpieces 18.
[0041] Manipulator 27 comprises a beam 33 that is mounted at an upright 34 pivotable about a vertical axis 35 that runs transversally with respect to pivot axis 22, as indicated by an arrow 36. Gripper 28 is mounted at beam 33 pivotable about a rotation axis 38 that runs transversally with respect to pivot axis 22 and with respect to vertical axis 35, as is indicated by an arrow 39.
FIG. 2 shows the machine tool from FIG. 1 in a top view, wherein [0042] headstock 14 and tool spindle 15 are merely indicated in dashes.
It can be seen in FIG. 2 that clamping [0043] device 21 is mounted at a base 41 at which also a motor 42 is provided for pivoting clamping device 21 about pivot axis 22.
Clamping [0044] station 29 comprises two clamping jaws 44 movable towards each other, which clamping jaws each comprise in a direction facing each other a curved surface 45 that is adapted in its contour to an outer contour of gripper 28 as indicated at 46.
A [0045] recess 47 is provided between clamping jaws 44, so that gripper 28 can be put between clamping jaws 44, without a workpiece 18 that possibly protrudes to the bottom being moved and/or coming into contact with a support surface 48 for clamping jaws 44.
Before clamping [0046] device 21 is pivoted into the position shown in FIG. 1 and 2 in which side 24 of workpiece 18 points to the top for machining, it is located in the position shown in FIG. 3, in which longitudinal sides 49 of workpiece 18 can be machined. It can be seen in FIG. 3 that workpiece 18 is part of a long workpiece bar that is pushed, step by step, through clamping device 21 from the left to the right.
In the position shown in FIG. 1, [0047] longitudinal sides 49 and front side 24 of workpiece 18 have been machined so that it can now be cut from the workpiece bar.
To this end, [0048] manipulator 27 grips workpiece 18 with its gripper 28, whereupon the tool shown in FIG. 1 that is a circular saw, then cuts workpiece 18 from the remaining workpiece bar.
[0049] Manipulator 27 pivots then to the side into the direction of arrow 36, rotating at the same time gripper 28 about rotation axis 38, so that front side 24 of workpiece 18 now points to the bottom.
As soon as [0050] gripper 28 has arrived over clamping station 29, it is lowered between clamping jaws 44 which then move towards each other and, thus, unshiftably lock gripper 28. This situation is shown in FIG. 4 in an enlarged detail.
It can be seen in FIG. 4 that clamping [0051] jaws 44 engage at jaws 50 of gripper 28 and center same and press same simultaneously onto support surface 48.
[0052] Jaws 50 comprise to this end a contour 51 that is adapted to the outer contour of workpiece 18. Contour 51 can be better seen in FIG. 5, where gripper 28 is shown without clamping station 29.
Returning to FIG. 4, another holding [0053] jaw 53 is shown in there that can be used for even better centering and holding of gripper 28.
With [0054] 54, compressed air or pneumatic hoses are shown through which jaws 50 of gripper 28 can be moved to-and-fro. The clamping forces that can be generated in that way are relatively low, but they are sufficient, however, for the workpiece not to change its position while being positioned between clamping device 21 and clamping station 29. As soon as gripper 28 is clamped into clamping station 29, clamping jaws 44 now exert pressure onto jaws 50, whereby workpiece 18 is safely held in jaws 50.

Claims

Therefore, what I claim, is:

1. A machine tool, comprising

a workpiece carrier for clamping a workpiece to be machined,

a headstock mounting a rotary-driven tool spindle adapted to clamp in tools for machining the workpiece,

a manipulator equipped with a gripper for gripping a workpiece clamped into the workpiece carrier, and

a clamping station designed to clamp in the gripper with a workpiece hold by the gripper,

said manipulator adapted for removing said workpiece from the workpiece carrier and inserting the gripper into the clamping station.

2. A machine tool as in claim 1, wherein the manipulator comprises a beam pivotably arranged about a vertical axis, the beam mounting the gripper pivotably about a rotation axis, said rotation axis running transversely with respect to the vertical axis.

3. A machine tool as in claim 2, wherein the beam is vertically adjustable into the direction of the vertical axis.

4. A machine tool as in claim 1, wherein the clamping station comprises clamping jaws for centering and holding the gripper, which clamping jaws are adapted to an outer contour of the gripper.

5. A machine tool as in claim 3, wherein the clamping station comprises clamping jaws for centering and holding the gripper, which clamping jaws are adapted to an outer contour of the gripper.

6. A machine tool as in claim 1, wherein the gripper comprises exchangeable jaws that are adapted to an outer contour of the workpiece.

7. A machine tool as in claim 2, wherein the gripper comprises exchangeable jaws that are adapted to an outer contour of the workpiece.

8. A machine tool as in claim 1, wherein the workpiece carrier comprises a clamping device that is transversely pivotable with respect to the vertical axis, such that the clamping device can position the workpiece into an orientation for machining of its side remote from the clamping device.

9. A machine tool, comprising

a workpiece carrier for clamping a workpiece to be machined,

a headstock mounting a rotary-driven tool spindle to clamp in tools for machining the workpiece,

a manipulator equipped with a gripper, said gripper comprising exchangeable jaws adapted to an outer contour of the workpiece for gripping the workpiece, and

a clamping station comprising clamping jaws for centering and holding the gripper with a workpiece hold by the gripper,

said manipulator adapting for transferring said gripper between a position at the workpiece carrier and a position in the clamping station.

10. A machine tool as in claim 9, wherein the clamping jaws of the clamping station are adapted to an outer contour of the gripper.

11. A machine tool, comprising

a workpiece carrier for clamping a workpiece to be machined,

a headstock mounting a rotary-driven tool spindle to clamp in tools for machining the workpieces,

a clamping station comprising clamping jaws adapted to an outer contour of the gripper,

said manipulator adapted for transferring said gripper between the workpiece carrier and the clamping station.

12. A machine tool as in claim 11, wherein the gripper comprises exchangeable jaws adapted to an outer contour of the workpiece.