GB2203678A

GB2203678A - Pellet changing mechanism

Info

Publication number: GB2203678A
Application number: GB08809118A
Authority: GB
Inventors: Arnold Dassler
Original assignee: Schwaebische Huettenwerke Automotive GmbH
Current assignee: Schwaebische Huettenwerke Automotive GmbH
Priority date: 1987-04-16
Filing date: 1988-04-18
Publication date: 1988-10-26
Anticipated expiration: 2008-04-18
Also published as: GB2203678B; FR2613969B1; IT8820215A0; DD268651A5; DE3713022A1; FR2613969A1; GB8809118D0; IT1217425B

Description

Pallet Changing Mechanism a? The invention relates to pallet changing

mechanisms.

Pallet changing mechanisms and systems play an important part in the production of components, particularly series components, as they are able to contribute to the reduction in the non-productive times. A rapid change in pallet is therefore of great importance. The pallet is in fact conveyed from the pallet support to the pallet changing mechanism on completion of the machining process, which will therefore take over the process of pulling out the pallet from or inserting it onto the pallet support.

The changing mechanism consists basically of at least two stations, both equipped with a transport mechanism.

The pallets set up for processing the workpieces, generally speaking.for machining, are located in an indexing station, whereas the other indexing station is in the waiting position for accepting the pallet in the machine station. There are several known systems for carrying out the pallet changing process. It is for example possible for two adjacent indexing station or two opposite stations to be mounted on a turntable.

Multi-pallet systems are also known where one or two stations are provided on a conveyance carriage to 2 transport the pallets between distributing stations and one or more machines.

It is to lock the pallets on the pallet changing mechanism by a locking device. A rapid locking operation is therefore required on the one hand because of the desired short non-productive times, however, it will be necessary on the other hand to provide a safe hold because of the high acceleration torques.

The object of the invention is to provide an improved pallet changing mechanism.

The present invention provides a pallet changing mechanism comprising a pallet clamping bed having at least one indexing station for a pallet, the pallet clamping bed having a locking mechanism for the pallet in or on the indexing station, that the locking mechanism having a movable locking member which is attached to the clamping bed at one end and forms a catch with its other end which is freei the catch being operable to engage a complementary formation located on a pallet to lock the pallet to the bed.

The pallets can be rapidly, and securely locked by the locking mechanism. As the locking member is 3 attached to the clamping bed at one end, it is able to latch into, engage or be attached in a different manner to the pallet in a simple manner.

Preferably the latching member is flexible at least in the area of its free end, where the locking or unlocking operation is being carried out using elasticity Accessory components for locking or unlocking can therefore be omitted or restricted to a minimum. The elasticity of the locking member can in fact be used for one or both types.

The locking member may be a leaf spring attached on one end to the clamping bed. The leaf spring may have a nose on the free end functioning as a catch, which engages in a cutout on a pallet to be locked or in a component attached to the pallet.

The leaf spring can by this design engage in the cutout in a simple manner so as to produce a safe and rapid clamp, which will lie securely in the cutout because of the elasticity of the leaf spring.

The cutout may be provided with a chamfer on the 4 side facing the leaf spring.

This measure allows a pallet pushed into the indexing station to be automatically locked, because the nose of the leaf spring will be deflected upwards at the chamfer and can then engage behind the cutout.

The unlocking and/or locking can alternatively be achieved by providing a contol mechanism which engages the locking mechanism at right-angles to its locking and unlocking direction.

The control mechanism can be used to raise the locking mechanism, e.g. the leaf spring in a simple manner so that it or they can be inserted in the cutout in the pallet or extracted from it.

The control mechanism may have a control rod which can move at right angles to the unlocking or locking direction to engage the leaf spring near he free end thereof and release the locking mechanism.

The control rod may be actuated pneumatically, mechanically or hydraulically. A restoring spring may be provided for restoring the control rod.

The control rod may be provided with position monitoring devices for safety, whereby it will be possible to establish whether the pallet concerned has been locked. Furthermore, or in order to introduce the locking operation, the pallet clamping bed may be provided with a stop bar which is used as a stop for the travel of the pallet to be locked. By providing the stop bar with the appropriate monitoring equipment, it will in this way be possible to indicate whether the pallet to be locked is located in the correct position.

The stop bar may be provided with one or more limit switches. The control bar of the control mechanism may be actuated via the limit switch of the stop bar to ensure a safe lock with inspection.

One embodiment of the present invention is described in more detail below, by way of example only and with reference to the accompanying drawings in which:- Fig. 1 is a partial longitudinal -section through a pallet changing mechanism according to the invention; and Fig. 2 is a sectional view of the locking mechanism viewed in the direction of arrow A of Fig. 1.

6 The pallet changing mechanism incorporates known features of design, so that it is principally the parts provided by the invention which are described in greater detail.

The drawing shows a rotatable pallet clamping bed with a central shaft 2, which is driven by a method not shown in greater detail. Several indexing stations 3 distributed around the circumference are connected to the shaft 2, an which the pallets 4 are locked.

The shaft 2 is fitted with a flange 5 on its free end. One end 8 each of leaf springs 6 are attached to the flange 5 as locking mechanisms by means of screws 7. Fig. 1 shows one complete leaf spring 6 and the second one only in part. The number and arrangement of the leaf springs will be based on the nature of the indexing station. The other free end of each leaf spring 6 is provided with a catch, namely a nose 9 with a stop edge 10. The length of each leaf spring 6 is selected such that the free ends with the noses 9 in each case project into the indexing station.

The pallets 4 or the component attached to the face of the pallets are in each case provided with a cutout 11 at such a level or position with, respect to 7 the flange 5 that the noses of the leaf spring 6 can be pushed through them. The cutouts 11 of the pallets 4 are provided with lead-in chamfers 12 on the sides facing the leaf springs so as to make it easier to insert the noses. Furthermore, it will also be possible for each nose 9 to be provided with a chamfer 13 matching the chamfer 12 at its front section, which will result in the leaf spring 6 being shifted upwards automatically when driving into the pallet 4 and engage behind the cutout with its impact edge 10 because of the elasticity of the leaf spring. A control mechanism 14 with a control rod 15 is located on a fixed part of 1 the pallet clamping bed 1. The longitudinal axis of the control rod 15 that can be shifted in the axial direction is located at right-angles to the longitudinal axis of the leaf spring, i.e. to the direction of shift of pallet 4. The front end of the control rod 15 is up against the bottom side of the leaf spring 6 in the front.section.

The control mechanism can comprise a piston and cylinder arrangement, as shown, formed by a cylinder 16 with piston chambers 17 and 18, the control rod 15 being shifted pneumatically or hydraulically. The piston chambers 17 and 18 are pressurised accordingly via a pneumatic or hydraulic source not shown in 8 greater detail. Position -monitoring elements 19 and 20 will indicate the position of the control rod 15 and hence the position of the leaf spring 6. Such position monitoring elements are generally known. They can for example function on electrical, magnetic or electromagnetic principles.

The control rod 15 is pushed forward (upwards in_ the drawing) by pressurising the piston chamber 18, whereby the leaf spring 6 is pushed up, when it is required to unlock the pallet 4. This must only rise high enough for the contact surface 10 to be released and the nose 9 can be pulled out of the cutout 11.

The control rod 15 can also be moved forward or upwards in the same manner to make the insertion easier instead of the pallet being lcoked via the spring force of the leaf spring.

The piston chamber 17 can be pressurised to lower the control rod 15, or a restoring spring may be used in a simple manner instead. The pallet clamping bed 1 is also provided with stop bars 21, which can in each case be slid into a cylinder 22. The stop bars 21 project out of the cylinder wiht their front ends. As is evident from Fig. 1, they are arranged such that 9 they can lie up against one wall 23 of the pallet 4 when the pallets are brought into position. The position of the stop bars 21 has therefore been chosen such that they are then pushed from a first forward position into a second back position against the force of a spring 24. The position of the pallet 4 to be locked will in this way be signalled if the stop bars 21 are provided with limit switches 25. Limit switches are also generally known, so that they are only shown in principle. They can for example be provided with a magnetic pin 26, which can also be shifted together with the stop bar 21 and which operates in conjunction with suitable sensors 27 reacting to the magnetism, which indicate the two positions of the control bar 21.

The control mechanism 14 with the control rod 15 can be operated via the sensors by known control mechanisms. This means that the control rod 1.5 is first psuhed out for the locking operation, i.e. for lifting the leaf spring 6, if a signal is received via the sensor 7 that the pallet 4 to be locked is located in the correct, i.e. in the position to be locked, as shown in Fig. 1.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

CLAIMS,

1. A pallet.changing mechanism comprisiRg a pallet clamping bed having at least one indexing station for a pallet, the pallet clamping bed having a locking mechanism for the pallet in or on the indexing station, that the locking mechanism having a movable locking member which is attached to the clamping bed at one end and forms a catch with its other end which is free, the catch being operable to engage a complementary formation located on a pallet to lock the pallet to the bed.

2. A pallet changing mechanism according to claim 1, 1 wherein the locking mechanism is flexible at least in the area of its free end, so that the locking or unlocking operation is carried out using elasticity.

3. A pallet changing mechanism according to claim 2, wherein the locking mechanism is a leaf spring attached at one end to the clamping bed.

4. A pallet changing mechanism according to claim 3, wherein the leaf spring has a nose as a catch on the free end, which engages in a cutout on a pallet to be locked 12 or in a component attached to the pallet.

5. A pallet changing mechanism according to claim 4, wherein the cutout is provided with a chamfer on the side facing the leaf spring.

6. A pallet changing mechanism according to any of the preceding claims, wherein the pallet clamping bed has a control mechanism which engages the locking mechanism at right angles to direction of relative movement when locking or unlocking a pallet.

7. A pallet changing mechanism according to claim 6, wherein the control mechanism has a control rod which can move at right-angles to the said unlocking or locking direction to engage the leaf spring near the free end thereof and release the locking mechanism.

8. A pallet changing mechanism according to claim 7, wherein the control rod is provided with a restoring spring.

9. A pallet changing mechanism according to claims 7 or 8, wherein the control rod is actuated pneumatically or hydraulically.

13

10. A pallet changing mechanism according to claim 9, wherein the control rod is provided with position monitoring elements.

11. A pallet changing mechanism according to any of the preceding claims, wherein the pallet clamping bed is provided with a stop member which acts as a stop for the pallet to be locked.

iz. A pallet changing mechanism according to claim 11, wherein the stop bar is provided with limit switches.

13. A pallet changing mechanism according to claim 11 or 12 and any of claims 6 to 9, wherein the control rod of the control mechanism can be actuated via the limit switches.

14. A pallet changing mechanism substantially as described above with reference to the accompanying drawings.

15. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.

lhllllillod 198,8 at The Patent Ofnce, State House, 66171 Holborn, London WC1R 4TP. Further copies may be obtalned from T lie Patent Office,