GB2282340A

GB2282340A - Machine for processing different shaft-like work pieces with a plurality of processing devices simultaneously

Info

Publication number: GB2282340A
Application number: GB9418472A
Authority: GB
Inventors: Franz Georg Bauer; Wolfgang Kinkelmann
Original assignee: GRIESHABER MASCH
Current assignee: GRIESHABER MASCH
Priority date: 1993-09-22
Filing date: 1994-09-14
Publication date: 1995-04-05
Also published as: GB9418472D0; DE9314316U1

Abstract

In a machine for exact processing of symmetrically balanced sections of the surface of shaft-like workpieces (18), particularly for working the surface of bearings on camshafts or crankshafts, by grinding the machine having at least one work station (24) which receives different shaft-like workpieces (18) and having at least one carriage (34) which is received and fixed in the shaft of the workpiece (18), the carriage (34) supporting a plurality of interchangeable workpiece processing devices (28, 28a) a number of which can be adjusted in distance with respect to each other and together with the carriage (34) can be positioned in relation to the workpiece (18), a common transport device being provided for setting the mutual distances (A) between the work piece processing devices (28), the workpiece is maintained between a spindle head (36) and a tail stock (26) which can be displaced and positioned in the direction of the axis of the workpiece (18) by a separate carriage (50) to facilitate the processing of different workpieces. <IMAGE>

Description

MACHINE FOR PROCESSING WORK PIECES DescriPtion The invention relates to a machine for exact processing of symmetrically balanced sections of the surface of shaft-like workpieces, preferably for working the surface of bearings on camshafts or crankshafts, having at least one work station which receives different shaft-like workpieces and has at least one carriage which is received and fixed in the shaft of the taken-up workpiece, wherein the carriage supports a plurality of interchangeable workpiece processing devices, an arbitrary number of which can be adjusted in distance in respect to each other and together with the carriage can be positioned in relation to the workpiece, wherein the workpiece is maintained between a spindle head and a tailstock.

A device of this type is known from US Patent 4,963,164.

The workpieces can be camshafts or crankshafts, for example. The processing machine and positioning device will be described below by way of example, using these shaft-like workpieces. Shafts of this type have dynamically balanced surfaces at a distance from each other, which represent bearings. Either the shaft itself is seated in these bearings or other parts of a machine, for example connecting rods of pistons of an internal combustion engine or of a pump or a compressor, extend around these bearings.

It is known to subject these dynamically balanced surfaces to a cutting surface treatment by means of grinding or superfinishing in order to improve the roundness and surface quality.

A super-finish stone is placed on the area to be worked and adapts itself to the curvature of the workpiece. It performs an oscillating motion in the axial direction. The workpiece rotates. But it is also known (US Patent 1,908,048) to employ a grinding belt in place of a tool stone or in addition to a profiled stone, which makes possible an overlapping processing.

Other grinding processes can also be employed.

It is furthermore known in connection with shaft-like workpieces to perform working of all axially adjoining bearings simultaneously, also when processing crankshaft journals, for example, the circularly symmetrical surfaces of which are moved out of the axis of the shaft around the crank throw. In this case it is required to make devices available which follow this deflection (US Patents 2,270,559 or 1,993,543).

However, the simultaneous working of all bearings of a shaft does not satisfy the requirements, which have been increased because of continuing automation, in connection with the rapid provision of such shafts, which have been finished and worked with the highest degree of quality, as parts in a manufacturing process for machines or engines. Instead, completely or almost completely automated processes require the clocked processing and availability of similar workpieces, such as camshafts or crankshafts. In spite of this, however, it should be possible without problems to convert an automatic processing machine by simple retooling for the processing of different workpieces.

But a mixed operation should also be possible with each type of shaft to be processed. Without any great retooling effort it should be possible to finish camshafts of arbitrary length and arbitrary shapes, i. e. with varied distances between the cam and the beginning and end of the camshaft as well as with bearings located between the cams, in such a way that shafts with totally unworked bearings are inserted and, following automatic processing, are taken out of the machine at the other end ready for installation. Insertion and removal should also be automatically possible. The insertion and removal stations must be designed for this. This requirement applies to camshafts as well as crankshafts. It must be possible to work different types of bearings for both components. At least one bearing of an arbitrary type of shaft has, for example, radial surfaces to be worked in order to absorb axial forces or to prevent axial play.

These radial surfaces must be processed the same as annular crowned surfaces of partly considerable, but always different, axial length. Edge areas must also be worked, also if these edge areas have curved radii.

Machines of this type are known from European Patent PuDlication EP 0 167 659 Al, for example. With this machine several workpiece processing devices can be displaced parallel with the axis of the workpiece and adjusted in defined positions on a carriage which is movable on a rail. In this way the machine can be adapted to variously designed workpieces. It has been shown to be disadvantageous that, in addition to the workpiece processing devices, the tailstock is also disposed on the carriage, so that it is also displaced when the carriage is moved. With the workpiece clamped it is therefore necessary to adjust the workpiece processing devices individually, although they are disposed on one carriage, or a corresponding number of workpiece processing devices must be available. However, this does not make economic sense if, for example with camshafts for 4- or 6-cylinder engines, the arrangement of the cams is repeated once or twice.

It is therefore the object of the invention to further develop a device of the type mentioned at the outset in such a way that the most diverse workpieces can be clamped and processed in an economical way and in a structurally simple manner, regardless of the number and arrangement of the tools.

In accordance with the invention this object is attained in that the tailstock can be moved and positioned on a separate carriage in the direction of the axis of the workpiece.

Since, besides the individual workpiece processing devices, the tailstock can also be placed by means of a movable carriage, the structural outlay for adapting the machine of the invention to different tools is small. On the one hand, these therefore can be clamped in a simple manner and, on the other hand, the workpieces can also be worked in sections without problems by moving the workpiece processing devices by section, which keeps the costs low. This carriage can be connected to the same control device.

For example, if a camshaft for a 6-cylinder engine is processed by the machine of the invention, the camshaft can be divided into three equal sections. The workpiece processing devices are adjusted on the carriage for the first section and this first section is worked. Following this the carriage with the workpiece processing devices correctly adjusted in their positions is only moved to the second section, which is then worked. The tailstock, which is provided on a second carriage, remains in its position. Finally, the carriage with the workpiece processing devices is moved from the second into the third section, which is then processed. Thus, workpiece processing devices are required for only a single section, i.e.

for a fraction of the cams and bearings of a camshaft, and the workpiece processing devices need only be arranged for this single section. After that they are only moved by means of their carriage. In the process the tailstock poses no obstacle, since it maintains its position on a separate carriage.

In accordance with a preferred further embodiment of the invention, the spindle head can be moved, positioned and fixed on a separate carriage in the direction of the axis of the workpiece. The most diverse workpieces can be clamped quickly and without problems regardless of their length by means of a movable tailstock and a removable spindle head. In this case the drive of the spindle head can either be moved along by means of the carriage or it can be fixedly attached on the machine frame, in which case the driveshaft still permits the movement of the spindle head.

Preferably the two carriages for the tailstock and the spindle head can be connected and/or are simultaneously movable.

The clamped workpiece can be moved underneath the workpiece processing devices in this way, so that with extremely long workpieces it is not necessary to have to move the carriage with the workpiece processing devices over the entire length of the workpiece in order to process it.

A further advantage and increased flexibility of the machine of the invention is achieved in that the workpieces are grasped by means of a V-block, wherein at least one, but in particular four V-blocks are provided on one pallet. The workpieces are moved on these pallets to the individual processing stations and then the entire pallet with the workpiece is placed into the processing area of the processing station.

If the pallet has different V-blocks, it is possible to grasp and transport different workpieces with this pallet. Therefore it is not necessary to retool the machine of the invention when a workpiece change occurs. Instead, it is only necessary to set a new program, which is adjusted to the new workpiece, so that the new workpiece is grasped by means of the V-blocks therefor provided. The new workpiece then can be lifted as before by means of the pallet into the processing area of the processing station.

The processing stations which are arranged behind each other straddle an endless conveyor which connects them and are basically designed the same. In principle they have an arbitrarily large number of individuals workpiece processing devices, which themselves are all interchangeable in order to make a flexible system possible. The further characteristic lies in that the workpiece processing devices first can assume a lateral parking position.

It is possible in the parked position to lock the tailstock on its own carriage and all non-needed workpiece processing devices on their own carriage and also to park them next to each other. From this parked position and still laterally in respect to the processing position, the workpiece processing devices can be adjusted to their exact distances from each other following unlocking before or after the clamping of the workpiece. This is accomplished by moving the tailstock via its carriage and of the individual workpiece processing devices on a support which supports all devices and is disposed the long way in each processing station. This support as well as the carriage of the tailstock are located transversely in respect to the endless conveyor and parallel to the shaft-shaped workpieces.

By means of a mechanical device, a screw spindle provided with an electrical turntable drive, a pneumatic or hydraulic device the tailstock and the workpiece processing devices can be brought into the desired position in respect to each other on the carriage or the support. A respective locked device can be moved in relation to the other locked devices. The lock can consist of an indexing device or a clamping. When all workpiece processing devices have taken up their exact distances from each other, which correspond to the distances between the dynamically balanced surface sections on the shaft-like workpiece to be processed, the support on which all workpiece processing devices are located can be moved sufficiently far in the processing position parallel to itself until the exact position in respect to the workpiece has been taken up. In an advantageous manner the displacement movement can be performed with the same device with which the distances of the individual workpiece processing devices on the support have been set. A locking of the support in respect to the processing station can also take place.

It is a further advantage that any desired number of workpiece processing devices can be positioned on the support.

The flexibility of the machine can be increased in this way. For example, it is possible to position only one or only two workpiece processing devices per processing station and to let them work on the workpiece. The rest of the workpiece processing devices remain locked in their parked positions laterally of the workpiece or laterally of its clamping, so that these workpiece processing devices which are not actually used on the one hand do not present an obstacle and, on the other, are quickly available when needed.

Processing of the workpieces by the plurality of the stations erected along the endless conveyor can either take place in multi-stages in such a way that finishing of the same surface is performed in a subsequent station, or that individual processing surfaces which are located too closely together and which, because of their proximity, cannot be processed in one station, are sequentially processed in subsequent stations, or individual stations can be designed for special processing.

Special processing can consist, for example, in that in this station the workpiece is not only given a rotating movement, but also a superimposed axially oscillating movement. By means of this it is possible in an advantageous manner to place a diagonally extending cut on a dynamically balanced bearing of a shaft-like workpiece. The direction of rotation of the workpiece can furthermore also be reversed.

As already mentioned above, the workpiece processing device is interchangeable in order to make the machine flexible by the use of different workpiece processing devices. For example, it is possible to employ conventional super-finishing devices with oscillating stones on a hingedly supported arm as a workpiece processing device. This device or other devices can be suspended in the workpiece processing device in such a way that during processing the profiled stones follow the bearing surface of a connecting rod bearing while it tumbles around the axis of a turning crankshaft.

In place of a super-finishing device it is possible to use a belt-finishing device with a supply of grinding belts of narrow design disposed on reels. Such belt-finishing devices are known per se. However, their adaptation to the machine of the invention requires solutions which cannot be simply derived from what is known, but require special considerations.

A belt-finishing device which can be employed in the machine in accordance with the present invention consists of a pneumatically or hydraulically closeable pair of tongs which encloses the dynamically balanced surface to be worked as soon as the device has been brought into position. The place to be processed is moved by the endless conveyor into the tongs which are in the open position, as will be explained in detail below.

The tongs are closed by the working medium which is under pressure and the required contact pressure is provided in this way. The opening and closing movement of the tongs is used in accordance with the invention for moving the grinding belt by the required amount for the subsequent working.

This belt-finishing device has the further characteristic that the tightened grinding belt is guided over a reversing roller having a groove in the circumferential direction. In case the belt tears, a spring-loaded sensor bolt falls into this groove and by this movement triggers an error report which stops the machine.

The differently usable workpiece processing devices are housed in cassettes. When using a belt-finishing device, for example, these cassettes also receive the grinding belt plus associated spare materials and the supply devices. In this way a rapid and unified change of the workpiece processing devices is assured.

Further details, characteristics and advantages of the invention ensue from the following description of an exemplary embodiment shown in the drawings and their supplements.

Crankshafts/camshafts are shown by way of example as the workpieces to be processed.

Fig. 1 is a schematic perspective representation of the cooperation of the essential parts of the machine; Fig. 2 is a schematic section through a processing station along the line II - II in Fig. 1, but not to scale; Fig. 3 shows the same section as Fig. 2 with the tools in a different position; and Fig. 4 shows the same section as Fig. 2 in a working position finally aligned with the workpiece.

Fig. 1 shows a partially schematic perspective view of the entirety of a finishing machine with multiple stations. It consists of an endless chain conveyor formed of two equal individual chains 10. At the inflow and outflow of the machine, these individual chains 10 are placed over reversing rollers 14 which are driven by means of drive shafts 12. The individual workpieces 18 are placed on V-blocks 22 which are provided on pallets 20. In accordance with the invention, each pallet 20 has different V-blocks 22, four different V-blocks 22 in the example of Fig. 1, so that it is possible to receive four different workpieces 18 with this pallet 20. The pallets 20, on each of which a workpiece 18 is seated in the V-blocks 22 provided for this, are conveyed to the individual processing stations 24 by means of the chain conveyor. The pallets 20 with the workpiece seated thereon are raised off the chain conveyor by means of a lift 25 and brought into the processing position for processing or possible intermediate storage in these processing stations 24.

In the process, the workpiece 18 is raised into the level of a spindle head 36 and is grasped by it and a tailstock 26. The spindle head 36 as well as the tailstock 26 are axially displaceable on a longitudinal broach guide 51 provided for this.

In this way the workpiece 18 can be aligned in respect to the individual workpiece processing devices prior to processing or in pauses during processing.

The spindle head 36 is connected with a drive for rotating the workpiece 18 around its axis. Workpieces, such as crankshafts or camshafts have several bearings which are simultaneously processed by a plurality of parallel tools. To be able to process different camshafts, the individual grinding tools can be freely positioned in respect to each other, as shown in Figs. 2 to 4. This positioning system consists of a support 30 on which individual workpiece processing devices 28 are placed in a displaceable and fixable way. This support 30 is disposed on a carriage 34 which can be moved by means of a threaded spindle 32.

The movable carriage 34 is guided in a carriage guide 38.

In their stand-by position, the individual workpiece processing devices 28 can additionally be fixed in place by means of index pins 44, which engage corresponding index holes 46 on the machine frame 40.

Fresh positioning of the workpiece processing devices 28 is required with each tool change and is performed as follows.

The workpiece processing devices 28 provided on the support 30 are clamped. The carriage 34 is placed into its right end position (Fig. 2) by means of the threaded spindle 32.

The workpiece processing devices 28 are aligned close together by an end stop 42 provided on the machine frame 40. In this stand-by position they are fixed in place on the machine frame 40 with index pins 44, which engage index holes 46 on the machine frame 40. Then, in accordance with Fig. 3, the workpiece processing device 28 which is closest to the workpiece 18 is clamped (F) to the support 20 and its index pin (44) is simultaneously loosened (L). Now the carriage 34 is moved by means of the threaded spindle 32 far enough into the work space that the distance A to the nearest workpiece processing device 28a, which is still in the stand-by position, fastened to the machine frame 40 by its index pins 44, is equal to the distance A between two bearings of the workpiece 18. The next of the workpiece processing devices 28a still in the stand-by position is loosened from the machine frame 40 (L) and clamped (F) to the support 30. The carriage 34 is now moved further into the work space until the desired distance has been set. All workpiece processing devices 28 are brought into their desired positions in respect to each other in this way. The carriage 30 as a whole can then be separately advanced toward the crankshaft 18. The tailstock 26 is shown in its working position in Fig. 4.

The size of the distances between the individual workpiece processing devices 28 is proportional to the number of revolutions of the turn of the threaded spindle 32 and in this way it can be subjected to a programmable control in a simple manner.

In the form of interchangeable cassettes, the workpiece processing devices 28 can receive grinding tools of the most different types, such as grindstone holders or grinding devices with grinding belts which are pressed against the shaft by pressure shoes. Turning of the grinding device by 90" for the exact working of vertical surfaces is also possible.

Four workpiece processing devices 28a to d have been drawn into the third processing station 24 (C) shown by way of example in Fig. 1. It is possible in this station 24 (C) to perform an axial back-and-forth movement of the workpiece 18 in addition to the rotating movement via the spindle head 36. To this end the spindle head 36 is connected with an oscillating drive, and the tailstock 26 is also given freedom of movement in the same axial direction against the effect of a mechanical or pneumatic or hydraulic spring. In this way it is possible to apply a cross cut to the bearings. The tailstock 26 is equipped with a corotating back center. The carriage 50 is seated in longitudinal broach guides 51 and in this way makes possible loading and unloading and the oscillating movement. In this case the loading and unloading movement is generated by a hydraulic cylinder 52, the piston rod of which is supported in a bearing block. A hydraulic reservoir is connected to this cylinder 52, which takes up the required prestress between the spindle head and the tailstock and the oscillating movement generated by the spindle head 36. A detent piston installed in the cylinder 52 makes possible loading free of displacement. After undoing a lateral clamping strip, the tailstock 26 can be displaced manually or automatically by means of a threaded spindle in the base position, by means of which the tip width is changed. The tailstock 26 can be exactly adjusted by means of an index strip.

Claims

1. A machine for exact processing of symmetrically balanced sections of the surface of shaft-like workpieces (18), preferably for working the surface of bearings on camshafts or crankshafts, having at least one work station (24) which receives different shaft-like workpieces (18) and has at least one carriage (34) which is received and fixed in the shaft of the taken-up workpiece (18), wherein the carriage (34) supports a plurality of interchangeable workpiece processing devices (28), an arbitrary number of which can be adjusted in distance (1) in respect to each other and together with the carriage (34) can be positioned in relation to the workpiece (18), wherein a common transport device is provided for setting the mutual distances (A) between the workpiece processing devices (28) and wherein the workpiece is maintained between a spindle head (36) and a tailstock (26), characterized in that the tailstock (26) can be displaced and positioned in the direction of the axis of the workpiece (18) by a separate carriage (50).

2. A machine in accordance with claim 1, characterized in that the carriage (50) has a support (51) for the tailstock (26).

3. A machine in accordance with claim 2, characterized in that the tailstock can be displaced and positioned on the support (51).

4. A machine in accordance with one of the preceding claims, characterized in that a common control device for displacing the carriages (34 and 50) is provided.

5. A machine in accordance with one of the preceding claims, characterized in that the carriage (34) with all the workpiece processing devices (28, 28a) positioned on it, and the carriage (50) with the tailstock (26) can be moved into a processing position in relation to the workpiece (18) and can be locked.

6. A machine in accordance with one of the preceding claims, characterized in that the transporting devices are embodied as hydraulic or pneumatic devices.

7. A machine in accordance with one of claims 1 to 5, characterized in that the transporting devices are embodied as a motor-driven threaded spindle (32), the rotational position of which can be stored in a program memory and can be called up from it.

8. A machine in accordance with one of the preceding claims, characterized in that the worpieces (18) are grasped by means of a V-block (22), wherein at least one, but in particular four V-blocks (22) are provided on a pallet (20).

9. A machine in accordance with claim 8, characterized in that each processing station (24) has one or a plurality of lifts (25) disposed next to each other, by means of which the pallet (20), together with the workpiece(s) (18) to be processed, can be raised into the processing space of the processing station (24).

10. A machine in accordance with one of the preceding claims, characterized in that the workpiece processing device (28) grasps the dynamically-balanced surface or surfaces on the workpiece (18) in the manner of tongs.

11. A machine in accordance with one of the preceding claims, characterized in that the tailstock (26) is provided in a parked position on a carriage (50) disposed parallel to the axis of the workpiece (18) laterally next to the path of the workpiece through the processing station (24) and can be locked in place there, and that after it is unlocked from this position can be moved on the carriage (50) against the workpiece (18) and locked in this position.

12. A machine in accordance with one of the preceding claims, characterized in that the clamped workpiece (18) performs a rotating and/or oscillating movement in respect to the workpiece processing device (28).

13. A machine in accordance with one of the preceding claims, characterized in that the workpiece processing devices (28, 28a) are super-finishing devices with one or a plurality of grindstones.

14. A machine in accordance with one of claims 1 to 12, characterized in that the workpiece processing devices (28, 28a) are grinding belt finishing devices with reels provided for the grinding belt in tongs enclosing the location to be processed, wherein when the tongs are opened or closed the grinding belt is moved on and the tongs in particular are operated by means of a pressure medium, and that two connections with a check valve are provided for the removable processing tool (28, 28a), which seal in the medium when the tool (28, 28a) has been removed, and wherein the grinding belt in particular is guided over a reversing roller having a groove in the circumferential direction which is engaged by a spring-loaded pin when there is no grinding belt present.

15. A machine in accordance with one of the preceding claims, characterized in that the workpiece processing devices (18) used for processing of the workpieces (18) are housed in quickly interchangeable cassettes which also include the required feed and storage devices and are interchangeable as a whole unit.

16. A machine in accordance with one of the preceding claims, characterized in that the spindle head (36) can be moved in the direction of the axis of the workpiece (18), positioned and fixed in place in a separate carriage (53).

17. A machine in accordance with one of the preceding claims, characterized in that the two carriages (50 a-nd 53) for the tailstock and the spindle head (25 and 36) can be connected with each other and/or simultaneously moved.

18. A machine substantially as hereinbefore described and as illustrated in the accompanying Figures.