WO2000003835A1

WO2000003835A1 - Machine tool with tool changing device

Info

Publication number: WO2000003835A1
Application number: PCT/EP1998/004349
Authority: WO
Inventors: Rudolf Haninger; Hans-Henning Winkler
Original assignee: Chiron-Werke Gmbh & Co. Kg
Priority date: 1997-06-11
Filing date: 1998-07-14
Publication date: 2000-01-27
Also published as: DE19724635C2; DE19724635A1

Abstract

The invention relates to a tool changing device (22) which can possibly be retrofitted on a machine tool (10) which comprises a working space (13) for machining workpieces (14) and a broach (11) in which a recess is provided for for tools (12) for machining the workpieces (14). The broach (11) comprises a possible automatic clamping device for the non-rotational clamping of the tools (12). The tool changing device (22) comprises an external tool magazine (25) and a device for taking a tool (12) from the external tool magazine (25) and placing it in the working space (13) so that the broach (11) can move towards the tool (12) and clamp it in place.

Description

Machine tool with tool changing device

The present invention relates to a machine tool which has a work space for machining workpieces, a spindle in which a receptacle for tools for machining the workpieces is provided, and a tool changing device which exchanges tools into the spindle from a machine magazine, the spindle being one automatic clamping device for rotationally fixed clamping of the tools in the receptacle.

Such machine tools are generally known.

In simple machine tools, the tools, which are often clamped in standardized tool holders, are inserted into the spindle by hand, where the clamping can also be done manually or automatically. The number of tools available is virtually unlimited in such simple machine tools, so that with one clamping any number of tools can be used one after the other in the work area.

The disadvantage here, however, is manual use, which is cost-intensive. On the other hand, it is disadvantageous that the tool change takes place relatively slowly, so that a very large chip-to-chip time results, which is undesirable. Such simple machine tools are therefore generally only suitable for small series.

Generic machine tools therefore have automatic tool changing devices that change tools from a machine magazine into the spindle. Two different types of magazines are known. In one magazine, the tools are held in a plate magazine, chain magazine, etc., one, preferably two gripper arms being provided on the spindle tube of the machine tool. While one of the two gripper arms removes a used tool from the spindle, the other gripper arm transfers a tool to be changed from the machine magazine into the holder in the spindle. This "push-pull mode" enables a very quick tool change to be carried out, the machine magazine generally traveling with the headstock, so that a "variable change level" results. This means that tools can be exchanged in almost every position of the work spindle. A disadvantage of the moving machine magazine, however, is that it can only accommodate the number of tools for which it is designed; subsequent expansion is not possible. For this reason, if the machine magazine is designed for a large number of tools right from the start, it has a corresponding weight, which is evident in the the speed of movement of the stand can prove disadvantageous.

The z. Currently, the fastest machine magazines / tool changing devices comprise gripper arms arranged on the spindle tube or on a sleeve, each of which carries its own tool, which remains on the tool gripper of the respective gripper arm both in a magazine position and in the working position. Such machine magazines / tool changing devices comprise 8, 12, 16 or even 20 gripper arms and thus tools to be stored. Because machine magazines equipped in this way do not require any movements of the machine magazines to provide the next tool for changing, very fast chip-to-chip times can be achieved.

A disadvantage of the machine tools described last, however, is that the number of tools that can be used in a workpiece clamping is limited. The number of gripper arms can no longer be increased at a later date, although the number of tools is limited to approximately 20 for geometric reasons, even in the case of new designs. It should also be borne in mind here that the tools are generally not held and clamped directly, but that they are attached to standardized tool holders, for example an SK or HSK tool holder. These standardized tool holders now again have considerable lateral dimensions, which results in the above-mentioned limitation with regard to the number of tools available. If workpieces are to be machined for which more different tools have to be used in a single clamping than is possible with the existing machine tools, the workpieces are usually machined on two or three different machine tools one after the other, but the workpieces from one in the other machine must be transferred, which leads to accuracy problems due to the different clamping.

It is also known to the applicant that workpieces can even be reclamped by spindle grippers, cradle plates, etc. on the same machine tool, so that this creates an even greater need for different tools, because the number of reclampings of a workpiece generally increases the number the tools to be used.

In summary, this means that the current requirements for machine tools are that more and more tools have to be made available, and the tool change must be able to be carried out very quickly. In addition, the investment costs associated with solving these problems should of course be as low as possible.

In this context, machine tools are known from DE 44 21 624 AI and DE 37 31 280 C2, in which tools are exchanged between the spindle and a tool magazine by means of a lifting and swiveling arm. The swivel arm can either carry out its own lifting movement itself, or it can be attached to a workpiece table, the lifting movement of which for lifting and lifting the tools into the or from the spindle. Either a plate magazine or a chain magazine is provided as the tool magazine.

A disadvantage of both machine tools is that the swivel arms have to perform relatively time-consuming movements in order to replace a tool between the tool magazine and the spindle, which leads to a slow tool change overall. Another disadvantage is that the tool change is only completed when the swivel arm pivoted into the work area has been completely moved out of the work area.

Against this background, it is an object of the present invention to develop the machine tool mentioned at the outset in such a way that the number of tools available is increased in a structurally simple manner and nevertheless a quick tool change is made possible.

According to the invention, this object is achieved in the machine tool mentioned at the outset in that a tool changing device is provided which comprises an external tool magazine and a device for placing a tool from the external tool magazine in the work space, in such a way that the spindle can start and clamp this tool.

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

The inventors of the present application have recognized that it is possible, in addition to the machine magazine with an associated tool changing device, Change device to be provided with an external tool magazine. The basic idea of the invention is to essentially use the positioning options of the spindle and its automatic clamping device by means of the device for placing a tool in order to receive and clamp a tool introduced into the working space.

Irrespective of the construction of the machine tool and the type of its machine magazine, additional tools can be provided by the external tool magazine, of which a z. Currently brought into the work area and can be picked up by the spindle for the next machining step.

For example, such tools can be stored in the external tool magazine that only have to be used relatively rarely, so that the longer time required for changing a tool from the external tool magazine does not entail any time disadvantages. It should be borne in mind here that because of the additional tool changing device, it is no longer necessary to reclamp a workpiece in another machine tool before the final work on this workpiece can be carried out. Overall, this results in a significantly more flexible production, especially since spindle grippers can now also be used to machine the workpiece in one and the same machine tool in different clampings. The number of tools to be used can be increased as required by the external tool magazine, the standard tools that are frequently used still being held in the machine magazine. In the new tool changing device, it is preferred if the tool changing device is constructed overall on a carrier which is fastened to a fixed workpiece table or a frame of the machine tool to be provided with the tool changing device.

This measure is structurally advantageous, the tool changing device can be retrofitted in a very simple manner, the carrier only has to be attached to the workpiece table or the frame of the machine tool to be retrofitted. All adjustments of the moving parts of the tool changing device can be made in advance.

It is further preferred if the device for placing a workpiece comprises a tool gripper with an actively opening gripper hand.

The advantage here is that the workpiece held is transported safely and can only be removed from the gripper hand by active opening. The held tool can therefore not fall out of the gripper hand even with very fast movements of the device.

It is further preferred if the tool gripper is a double gripper with two gripper hands, the positions of which can be interchanged by pivoting the double gripper.

There are a number of advantages associated with this measure. On the one hand, with a single positioning of the tool gripper in the work area, the double gripper enables both a tool to be removed from the spindle and - according to swiveling the double gripper - to change a new tool brought in. In this way it is also possible to change a whole range of tools from the external tool magazine into the machine magazine relatively quickly. After the spindle has deposited an old tool and removed a new tool from the tool changing device, this new tool can now be transferred into the machine magazine by the usual tool changing device, whereupon another tool is then inserted from the machine magazine into the spindle and then with the help the tool changing device to be exchanged for another tool from the external tool magazine. In this way, tools can be quickly transferred between the machine magazine and the external tool magazine with relatively few movements.

It is further preferred if the or each gripper hand can be actuated via a pin which projects upwards and which is to be pressed down to open the gripper hand.

This measure is known per se. Such a gripper with an actively opening hand that closes automatically under spring force is known, for example, from European Patent EP 0 291 828, to which reference is expressly made here. The advantage of using such a gripper hand is that, on the one hand, the tools or the tool holder are held securely by the closing spring forces and that the gripper hand cannot be accidentally opened, especially during rapid placement. Another advantage is that the gripper hand can be opened anywhere, for example by moving to a fixed stop. in the In connection with the new tool changing device, however, the gripper hand is opened via the spindle tube, which comes into contact with the bolt when the spindle pushes, so to speak, onto the tool placed in the work space. However, this means that no further actuating devices have to be provided on the new tool changing device in order to actively open the gripper hand moved into the working space. Rather, the movement of the spindle is used for this active opening.

It is then further preferred if the workpiece gripper is arranged on a swivel arm in such a way that it does not change its angular orientation when the swivel arm is swiveled about its swivel axis into or out of the working space.

The advantage here is that the tool gripper can be moved into the work space in a simple and quick manner by the swivel arm, with the further advantage that the alignment of the tool gripper is maintained during this swiveling, so that no subsequent position corrections are required.

It is then preferred if the tool gripper sits on a shaft which can be rotated via a belt which runs through the swivel arm and is driven by a further shaft which runs concentrically to the swivel axis.

The first advantage here is that the tool gripper can still be rotated even if it has been pivoted into the work area. For changing tools via the double gripper Furthermore, it is not necessary to approach the double gripper twice differently with the spindle, rather the double gripper can, for example, make a 90 ° or 180 "rotation, which is brought about by the belt drive. The concentric arrangement of the drive shaft of the belt drive also ensures that the workpiece gripper does not change its angular orientation when it is swiveled into the work area, it is only necessary for the two belt wheels on the two shafts to have the same diameter.

It is further preferred if the external tool magazine is mounted so as to be longitudinally displaceable so that it can be moved towards the tool gripper for the tool transfer.

It is advantageous here that a further movement, decoupled from the other movements, is provided for the tool transfer between the external tool magazine and the tool gripper, which can be implemented on the carrier in a structurally simple manner. Furthermore, the above-mentioned belt drive is structurally particularly simple if the tool gripper does not change its position on the swivel arm.

In a further development it is preferred if the tool magazine holds the tools under spring tension, an actuating mechanism for the tool gripper preferably being provided in the area of the tool magazine in order to open the tool gripper for the transfer of a tool to the tool magazine. These measures are structurally advantageous, they enable a targeted, active transfer of tools to the tool magazine, the actuating mechanism determining whether the tool gripper inserts or removes a tool from the tool magazine.

It is further preferred if the tool magazine is a plate magazine or a chain magazine.

The advantage here is that plate magazines are very simple and can be replaced as a whole if necessary.

Here it is further preferred if the plate magazine is rotated via a Maltese cross gear.

This measure is also structurally advantageous. As is generally known, a Maltese cross gear can be easily disengaged, so that the longitudinally displaceable mounting of the tool magazine can be easily realized. It is not necessary for the motor and the pin of the Maltese cross gear to be moved as well.

On the other hand, it is preferred if the plate magazine is rotated by means of a servo motor which, together with the plate magazine, is mounted so as to be longitudinally displaceable.

The advantage here is that a servo motor allows the plate magazine to be rotated much faster than is the case with a Maltese cross gear. With the help of the servo motor, intermediate positions can be passed over, which is not the case with a Maltese cross gear. Indeed The servo motor must now be mounted in a longitudinally displaceable manner together with the plate magazine, because it must not become disengaged from the plate magazine in order not to lose its position information.

The new, retrofittable tool changing device includes various drives that are decoupled from each other. On the one hand, there is a swivel drive attached to the carrier, via which the swivel arm is swiveled into the work area. A rotary drive for the tool gripper works through the swivel arm. This rotary drive is a belt drive with two pulleys, which lie in the axis of rotation of the tool gripper or the swivel axis of the swivel arm. Furthermore, a drive is provided for linearly moving the plate magazine onto the tool gripper to and from the tool gripper. This movement takes place when the tool gripper is withdrawn from the work area and is in a position opposite the plate magazine. By pushing together between the tool gripper and the plate magazine, a tool or tool holder is now held, so to speak, both by the tool gripper and by the plate magazine. Fixed jaws are provided both on the plate magazine and on the gripper hand, which engage from different sides but towards each other in the gripper groove on the tool holder. The springs of the plate magazine act on one side of the fixed jaws, while the movable jaws of the gripper hand are arranged on the other side. If the movable jaws are now opened, the tool remains in the plate magazine, while when the jaws are closed, it is pulled out of the plate magazine when it is withdrawn again. For the actuation of the movable jaws, a type of lever is provided which presses on the bolt over which the movable jaws are spread. The fifth independent drive is the rotary drive for the plate magazine. All five drives are arranged on the carrier of the tool changing device so that they can be adjusted to one another before a machine tool is equipped with the new tool changing device.

Further advantages result from the description and the attached drawing.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination indicated in each case, but also in other combinations or on their own without departing from the scope of the present invention.

The invention is illustrated in the drawing and is explained in more detail in the following description. Show it:

Figure 1 shows a new machine tool in a schematic side view and provided with the new tool changing device.

FIG. 2 shows a plan view of the machine tool from FIG. 1;

3 shows a plan view of the plate magazine of the machine tool from FIG. 1; Fig. 4 is a schematic side view showing the interaction of the plate magazine and gripper hand in the machine tool of Fig. 1;

5 shows a schematic side view of the belt drive for the gripper hand in the machine tool from FIG. 1;

6 different stages when changing a tool between spindle and external tool magazine;

7 shows a schematic and partial side view of the tool changing device of the machine tool from FIG. 1, with a gripper arm in the working position; and

Fig. 8 is an illustration like Fig. 7, but with the tool in the magazine position.

In Fig. 1, 10 denotes a machine tool, which comprises a spindle 11, in which a tool 12 is clamped in order in a work space 13 a schematically indicated workpiece

14 to edit. The workpiece 14 is on a workpiece table

15 spanned.

The machine tool 10 comprises a machine magazine 16 in which various tools 12 are held in their magazine position at 45 °. Such a tool 12 'is shown in FIG. 1. Each of the tools 12, 12 'is held by its own gripper arm, as will be described in connection with FIGS. 7 and 8. The machine tool 10 comprises a machine frame 17, on which the workpiece table 15 is fastened on the one hand. On top of the machine frame 17 there is also a first carriage 18 which can be moved perpendicular to the plane of the drawing. A second carriage 19 sits on the first carriage 18 and can be moved horizontally in the plane of the drawing in FIG. 1. On this second carriage 19, in turn, a spindle head 21 is seated, which carries the spindle 11, which can be experienced vertically in the plane of the drawing in FIG. 1. Through the first slide 18, the second slide 19 and the spindle head 21, the spindle 11 can move to almost any point in the working space 13 of the machine tool 10 in order to machine the workpiece 14 at any point. During this processing, different tools 12, 12 'can be exchanged from the machine magazine 16. Often, however, the number of tools 12, 12 'stored in the machine magazine 16 is not sufficient to be able to carry out all the machining operations to be carried out on a workpiece 14 in a single machine tool 10. In the machine tool shown in a schematic side view from the left in FIG. 1, a total of twelve tools 12, 12 ′ are present in the machine magazine 16.

In order to increase the number of tools 12, 12 ', the machine tool 10 is provided with a tool changing device 22, which is arranged in FIG. 1 behind the workpiece table 15 and the spindle 11, as can be seen better from FIG. 2. In order to be able to show the upper part of the tool changing device 22 in FIG. 1, the spindle head 21 was shown partially broken away. The tool changing device 22 is constructed with all of its units on a carrier 24 which is fastened to the rear of the machine frame 17. Alternatively, it would also be possible to attach the carrier 24 to the workpiece table 15. Because the tool changing device 22 is a compact, independent unit, it can also be retrofitted to existing machine tools at any time. Depending on the design of the machine tool to be retrofitted, the carrier 24 is mounted on the machine frame 17 or on the workpiece table 15.

The tool changing device 22 essentially comprises two structural units, namely an external tool magazine 25, in which further tools 12 are held. Furthermore, a device 26 for placing the tools 12 in the work space 13 is provided.

A type of portal arm 27 is arranged on the carrier 24 and carries the external tool magazine 25 at its upper end. The device 26 comprises an associated swivel arm 28 which can be swiveled about a swivel axis indicated at 29, for which purpose a swivel drive 31 is provided.

In the exemplary embodiment in FIG. 1, the pivot drive 31 comprises a piston-cylinder unit 33 which is pivotably attached to the carrier 24 about a pivot axis 32 and whose piston 34 is pivotably mounted on the pivot arm 28 about a pivot axis 35.

When the piston 34 is extended, the pivot arm 28 pivots about the pivot axis 29 out of the plane of the drawing in FIG. 1 and into the working space 13, as is shown in FIG. 2 will be explained in more detail below. When the piston 34 is retracted, the swivel arm 28 is correspondingly moved back into its position shown in FIG. 1.

At its free outer end, the swivel arm 28 carries an upwardly pointing tube 37, at the upper end of which a swiveling tool gripper 38 is arranged. The tool ripper 38 is set up to remove tools 12 from the external tool magazine 25 or to return them to the latter. How the transfer of tools between the tool gripper 38 and the external tool magazine 25 takes place is explained below with reference to FIGS. 3 and 4.

The portal arm 27 carries at its upper end a rail 41 which, in the position shown in FIG. 1, runs approximately parallel to the swivel arm 28. A slide 42 is guided on the rail 41 so as to be longitudinally displaceable in the direction of an arrow 43, a slide drive 44 being provided in order to push the slide 42 back and forth between its two end positions.

The carriage 42 carries a plate magazine 45 pointing downward, in which the tools 12 are held. A chain magazine can also be used instead of the plate magazine 45. A Maltese cross gear 46 is provided at the top of the carriage 42 and rotates the plate magazine 45 via a motor 47 with a crank 48. Each revolution of the crank 48 switches the plate magazine 45 by one position, the various positions defined in this way being selected such that a tool 12 or a tool holding place in the plate magazine 45 as well as a tool holding place or a tool 12 ' ^• in face the tool gripper 38. For handing over tools 12 between the tool gripper 38 and the plate magazine 45, the latter is now moved in the direction of arrow 43, so that both the tool gripper 38 and the plate magazine 45 are briefly engaged together on the tool 12 ″.

In a manner yet to be described, an actuating movement is now exerted on the tool gripper 38 by an actuating mechanism indicated at 49 in the direction of an arrow 51, so that the tool gripper 12 'is released so that it remains in the plate magazine 45, or a tool 12 is gripped so that it pulls it out of the plate magazine 45 when the carriage 42 moves back.

A further pivot drive 52 is provided under the carrier 24, by means of which the tool ripper 38 can be pivoted about its pivot axis indicated at 53. In the exemplary embodiment in FIG. 1, the swivel drive 52 comprises a piston-cylinder unit 54 which is mounted on the carrier 24 such that it can be rotated about a swivel axis 55. With its piston 56, the piston-cylinder unit 54 is connected in an articulated manner to a lever 57 which can be rotated about the pivot axis 29. By rotating the lever 57, a belt drive is actuated, which runs through the hollow swivel arm 28 and rotates the tool gripper 38. How this is done is described in connection with FIG. 5.

2 shows the machine tool 10 from FIG. 1 in a top view. It can first be seen that the tool gripper 38 is a double gripper 61 with two gripper hands 62, 63. By pivoting about the pivot axis 53 by means of the pivot drive 52, one of the two gripper hands 62, 63 aligned so that it points to the plate magazine 45 in which the tools 12 are stored.

In the position shown in FIG. 2, the gripper hand 62 has gripped a tool 12 ', while the gripper hand 63 is empty and can pick up a new tool.

By extending the piston rod 34, the swivel arm 28 is now pivoted into the position shown horizontally in FIG. 2, so that the tool gripper 38 enters the working space 13 of the machine tool 10. The pivot arm 28 pivots about its pivot axis 29, while the piston-cylinder unit 33 rotates about the pivot axis 32 and the pivot axis 35, which causes the pivot arm 28 to extend.

2, the spindle 11 is indicated with a solid circle, gripper arms 64 of the tool magazine 16 being indicated schematically by twelve dash-dotted lines which emanate from the spindle 11. It can be seen that the gripper arms 64 leave an angular range 65 of approximately 90 °. This area 65 faces the machine frame 17.

Before pivoting the swivel arm 28 along an arrow 66 into the working space 13, the spindle 11 is shifted into the position shown at 11 ', so that the tool gripper 38 is pivoted through the angular region 65 under the spindle 11. The swivel arm 28 itself passes under the tools 12 ', which are in their magazine position, while the tube 37 projecting further upward with the tool gripper 38 attached there (see FIG. 1) to avoid Collisions with the tools 12 'must be performed through the angular range 45.

The gripper hand 63 now removes the tool 12 from the spindle 11, whereupon the tool gripper 38 is then rotated about its pivot axis 53, so that the tool 12 'can now be inserted into the spindle 11. The swivel arm 28 is then pivoted back out of the working space 13 and the tool 12 which has been taken over can be stored in the plate magazine 45.

The transfer between spindle 11 and gripper hand 61, 62 takes place in that the spindle moves onto the tool from above, whereupon the tool is then automatically clamped in the spindle. In this context, the gripper hand is also actively opened in a manner to be described, so that the spindle can remove the tool. When a tool is inserted from the spindle into a gripper hand, the spindle in turn moves to the gripper hand, whereupon the tool is disengaged and automatically closed when the spindle is raised.

The tool changing device 22 can thus be used both for transferring tools between the machine magazine 16 and the plate magazine 45 and for short-term replacement for a single machining of a tool 12 from the plate magazine 45 into the spindle 11. Through the plate magazine 45, which in turn is simply exchanged , there is the possibility here of increasing the number of available tools 12 almost as desired, the replacement by means of the tool changing device 22 being only insignificant is slower than the tool change with the machine magazine 16 itself.

In Fig. 3, the plate magazine 45 is shown in a plan view. It initially comprises a carrier plate 71, in which semi-circular receptacles 72 are provided in cross section. U-shaped spring pieces 73 are arranged around the receptacles 72 and serve to hold the tools 12, as will now be described with reference to FIG. 4.

4, the area of the plate magazine 45 is shown schematically in a side view. First of all, it can be seen that the spring pieces 73 are provided on the support plate 71 below the receptacles 72, the latter forming fixed jaws 74 with which they engage in a conventional gripper groove 75 of a tool holder 76. The spring pieces 73 grip the tool holder 76 on its shaft 77 below the gripper groove. The tools 12 are each provided with such a tool holder 76 in a known manner.

To the left of the tool holder 76, the tool gripper 38 is indicated on its tube 37, the gripper hand 62 pointing to the tool holder 76. The gripper hand 62 also has fixed jaws 78 which engage in the gripper groove 75, whereby they do not collide with the fixed jaws 74 of the plate magazine 75. Movable jaws 79, which can be actively opened, are provided above the fixed jaws 78. The movable jaws 79 are biased into their closed position by a spring, where they hold a received tool holder 78 above the gripper groove 45. By pressing on a bolt 81, the movable jaws 79 can be pressed against the force of their rer closing springs are opened, thereby releasing a held tool holder 76 so that it can be removed laterally from the fixed jaws 78. Such a gripper hand is described in detail in European patent EP 0 291 828 B1, so reference is made to this document for further details.

To actuate the bolt 81, the actuating mechanism 49 is provided on the carriage 42, which comprises a lever 82 which is rotatably mounted on the carriage 42 at 83. To actuate the lever 82, a piston-cylinder unit 84 is provided which has a bolt 85 which lies in an elongated hole 86 on the lever 82. If the piston-cylinder unit 84 is retracted in the direction of an arrow 87, the lever swings up with its front free end 88 into the position shown in broken lines. The carriage 42 can be moved by the carriage drive 44 along the arrow 43 to the tool gripper 38, the lever 82 being in its solid position, so that the bolt 81 comes under the free end 88, is pressed down and the movable Bak 79 actively opens. By pulling the lever 82 back into the position shown in dashed lines, the movable jaws 79 are then closed again, so that when the slide 42 moves back, the tool holder 76 is held firmly in the gripper hand 62 so that it can be pulled out of the spring piece 73.

On the other hand, if a tool holder 76 is to be inserted into the plate magazine 45, the lever 82 remains in the position shown in solid lines when the carriage 42 is retracted, where the movable jaws 79 are open. The tool holder 76 will now removed from the gripper hand 62 by the force of the spring pieces 73.

An alternative drive for the plate magazine 45 is also shown in FIG. 4. The carrier plate 71 sits here on a shaft 89 which is driven by a servo motor 90. The servo motor 90 must also be attached to the carriage 42, while this was not necessary for the motor 47, since there the Maltese cross gear 46 can easily be disengaged. The advantage of the servo motor 90 is, however, that the plate magazine 45 no longer has to be clocked step by step, but that any positions can be approached immediately.

In Fig. 5 is a sectional and schematic side view of the belt drive for pivoting the tool holder 38 is shown in more detail.

First of all, it can be seen that a shaft 91 is arranged in the tube 37, which can be rotated about the pivot axis 53 and carries the tool gripper 38 at its upper end. At its lower end, the shaft 91 is connected to a belt pulley 92, on which sits a belt 93 which extends through the hollow swivel arm 28 to a further belt pulley 94. The pulley 94 is seated on a shaft 95 which can be rotated about the pivot axis 29. At its lower end, the shaft 95 merges into the lever 57, which is connected to the piston-cylinder unit 54 so as to be rotatable about a pivot axis 96.

The swivel arm 28 is connected to a tube 97 which is concentric with the shaft 95, rotatably receives it and itself rotatably sits in a sleeve 98, which in turn is attached to the carrier 24. A pin 99 is also provided on the swivel arm 28, which runs concentrically to the swivel axis 35 and ensures the articulated connection to the piston-cylinder unit 33.

Extending the piston-cylinder unit 54 is now implemented via the lever 57 into a rotary movement of the pulley 94 and via the belt 93 into a rotary movement of the pulley 92, which in turn causes the tool gripper 38 to be pivoted. Regardless of the pivoting of the tool gripper 38, the pivot arm 28 can be pivoted via the piston-cylinder unit 33, the tube 97 then rotating in the sleeve 98. This pivoting of the swivel arm 28 has no influence on the angular alignment of the tool gripper 38 to the carrier 24, if in particular the two pulleys 92, 94 are correspondingly matched to one another. When the swivel arm 28 is pivoted, the lever 57 is held in place by the piston-cylinder unit 54, so that the pulley 94 cannot rotate. When pivoting the swivel arm 28, the belt 93 now winds, so to speak, in the swivel direction around the pulley 94, as a result of which the pulley 92 is rotated relative to the swivel arm 28, so that the tool gripper 38 also rotates relative to the swivel arm 28. The pivoting movements of the swivel arm 28 to the carrier 24 and the tool gripper 38 to the swivel arm 28 compensate each other, so that the angular orientation of the tool gripper 38 to the carrier 28 is maintained. This results in a very simple positioning, as will now be shown in connection with FIG. 6. 6 schematically indicates the individual steps that have to be carried out so that a tool 12 accommodated in the spindle 11 can be replaced by a tool 12 ′ that has already been gripped by the double gripper 61. This initial situation is shown in Fig. 6a.

6b, the swivel arm 28 was pivoted into the work area, so that the double gripper 61 is now arranged under the spindle 11. The spindle 11 now moves the tool 12 into the gripper hand 62, opening the movable jaws with its spindle tube, as has already been described with reference to FIG. 4. The end face of the spindle tube acts here just like the free end 88 of the lever 82 from FIG. 4.

After the tool 12 has been inserted into the gripper hand 62, the spindle 11 disengages the tool 12 and moves upwards so far that it releases the tool holder to which the tool 12 is attached.

At the transition to Fig. 6c, the tool gripper 38 was pivoted by 90 °, so that now the tool to be changed 12 '' is below the spindle 11, so that it can now move with its receptacle onto the tool holder, with the movable jaws of the gripper hand at the same time 63 can be opened. However, the tool holder cannot fall out of the gripper hand 63, since it is held in the longitudinal direction by the fixed jaws 78 (FIG. 4) of the tool holder 38, while it cannot tilt, since its upper, conical end is already in the holder of the Spindle 11 is seated. After clamping of the tool in the spindle 11, the spindle 11 can thus laterally remove it from the gripper hand 63.

The tool holder 38 is now pivoted again in front of the plate magazine 45, which has meanwhile been rotated further, so that the empty space 100 from which the tool 12 'has been removed is no longer opposite the tool gripper 38.

The plate magazine 45 is now moved in the direction of the arrow 43, so that the empty gripper hand 63 can remove another tool 12 '' 'from the plate magazine 45. This removal takes place in the manner already described in connection with FIG. 4.

After moving back the plate magazine 45, the tool gripper 38 now carries two tools 12, 12 ″ ″, while in the plate magazine 45, in addition to the empty space 100 that the tool 12 ″ left, another empty space 101 was created.

The tool holder 38 is now pivoted back again by 90 °, whereupon the tool 12 is then inserted into the empty space 101 by moving the plate magazine 45. 6f the starting position according to FIG. 6a is reached, so that the tools 12 ″ and 12 ″ ″ can now be exchanged for one another with the sequence described.

The machine magazine 16 and details of the spindle 11 will now be described with reference to FIGS. 7 and 8. As already mentioned, the machine magazine 16 comprises a plurality of gripper arms 64, each of which carries a tool holder 76. Such a tool holder 76 is shown in Fig. 7 so that it with his Hollow shaft taper 102 sits under a receptacle 103 of the spindle 11. The gripper arm 64 is seated on a sleeve 104 which can be displaced longitudinally to the spindle 11, the hollow shaft taper 102 now entering the receptacle 103 by moving the sleeve 104 upward in FIG. 7. A clamping device 105 is provided in the interior of the spindle 11, which has clamping claws etc. at its lower end in a manner known per se, by means of which the hollow shaft taper 102 is clamped non-rotatably in the receptacle 103. The gripper arm 64 is part of a parallelogram guide 106, which is actuated via a piston-cylinder unit 107, in a manner known per se.

When the piston-cylinder unit 107 is retracted in the position shown in FIG. 7, the tool holder 76 is shifted into the magazine position shown in FIG. 8, in which its longitudinal axis 108 is at an angle of approximately 45 ° with the axis of rotation 109 of the spindle 11 .

In Fig. 8, the tool holder 38 is indicated schematically and in dashed lines below the spindle 11, only its actuating bolt 81 being shown in more detail. In order to now open the tool holder 38, the spindle 11 moves downward in FIG. 8 and in doing so presses with its end face 110 of its spindle tube 111 onto the bolt 81, as a result of which the tool holder 76 is released, as will be further explained in connection with FIG. 4 has already been discussed in detail. It should also be mentioned that the spindle 11 rotates in the spindle tube 111.

Claims

claims

1. Machine tool which has a working space (13) for machining workpieces (14), a spindle (11) in which a receptacle (103) for tools (12) for machining the workpieces (14) is provided, and a tool changing device ( 64), which exchanges tools (12) into the spindle (11) from a machine magazine (16), the spindle (11) comprising an automatic clamping device (105) for non-rotatably clamping the tools (12) in the receptacle (103) ,

characterized in that it comprises a tool changing device (22) having an external tool magazine (25) and a device (26) for placing a tool (12) from the external tool magazine (25) in the working space (13), such that the spindle (11) can approach and clamp this tool (12).

2. Machine tool according to claim 1, characterized in that the tool changing device (22) is constructed overall on a carrier (24) on a fixed workpiece table (15) or a frame (12) of the machine tool to be provided with the tool changing device (22) (10) is attached.

3. Machine tool according to claim 2, characterized in that the device (25) for placing a tool comprises a tool gripper (38) with an actively opening gripper hand (62, 63).

4. Machine tool according to one of claims 1 to 3, characterized in that the tool gripper (38) is a double gripper (61) with two gripper hands (62, 63), the positions of which are interchangeable by pivoting the double gripper (61).

5. Machine tool according to claim 3 or 4, characterized in that the or each gripper hand (62, 63) can be actuated via an upwardly projecting pin (81) which is to be pressed down to open the gripper hand (62, 63).

6. Machine tool according to one of claims 3 to 5, characterized in that the tool gripper (38) on a swivel arm (28) is arranged such that it when swiveling the swivel arm (28) about its pivot axis (29) in or out of Work area (28) does not change its angular orientation.

7. Machine tool according to claim 6, characterized in that the tool gripper (38) sits on a shaft (91) which can be rotated via a belt (93) which extends through the swivel arm (28) and from a further shaft (95) is driven, which runs concentrically to the pivot axis (29).

8. Machine tool according to one of claims 1 to 7, characterized in that the external tool magazine (25) is mounted in a longitudinally displaceable manner, so that it can be moved towards the tool gripper on the tool gripper (38).

9. Machine tool according to one of claims 1 to 8, characterized in that the external tool magazine (25) holds the tools (12) under spring tension.

10. Machine tool according to one of claims 1 to 9, characterized in that in the area of the tool magazine (25) an actuating mechanism (49) for the tool gripper (38) is provided to the tool gripper (38) for the transfer of a tool (12) to open the tool magazine (25).

11. Machine tool according to one of claims 1 to 10, characterized in that the external tool magazine (25) is a plate magazine (45) or a chain magazine.

12. Machine tool according to claim 11, characterized in that the plate magazine (45) is rotated via a Maltese cross gear (46).

13. Machine tool according to claim 11, characterized in that the plate magazine is rotated via a servo motor (90) which, together with the plate magazine (45), is mounted so as to be longitudinally displaceable.