GB2082098A

GB2082098A - Pallet registration apparatus

Info

Publication number: GB2082098A
Application number: GB8124798A
Authority: GB
Original assignee: Milacron Inc
Current assignee: Milacron Inc
Priority date: 1980-08-18
Filing date: 1981-08-13
Publication date: 1982-03-03
Also published as: JPS5741150A; FR2488540A1; FR2488540B1; GB2082098B; DE3115586A1; DE3115586C2

Abstract

The apparatus comprises a pallet (13) which slides onto a pallet receiver (24), the pallet receiver having a base (18) provided with locating pins or rails (20). The pallet has sockets accepting registration pins (67) provided on the receiver. An element (80) fixed in each socket has a diaphragm-like compliant mounting web (78). This allows vertical but not radial flexing so that initial vertical movement towards a clamping position of the pallet and pallet receiver causes inter-engagement between the pin and element. Final movement towards the pallet clamped position causes the locating pins or rails to come into contact with lips (22) of the pallet to securely and rigidly locate the pallet relative to the pallet receiver in orthogonal directions. The pallet is lowered by the receiver gripping the pallet lips, the receiver being lowered by a piston therein. <IMAGE>

Description

SPECIFICATION Pallet registration apparatus This invention generally relates to machine tools, and in particular, to machine tools employing interchangeable workpiece supports commonly, and hereinafter, called pallets which are fixed or registered on a pallet receiver base adjacent to the machine base.

The interchange of pallets on a machine tool is a well developed art, wherein pallets having a common machine registration surface may be employed to mount workpieces on the machine. By the use of common pallets, a first workpiece may therefore be operated upon by a machine cutter while a second workpiece may be fixed at a position remote from the machine to a pallet for subsequent interchange with a finished workpiece. The interchange of workpiece pallets may be automatic by pallet interchangers, or may be manual, carried out by an operator.

Final registration and location of the pallet with respect to the machine tool is of critical importance, and a variety of pallet locators have been employed in the prior art. One prior assembly disclosed in U.S.

Patent 3,054,333 consists of a plurality of conical locating pins on a receiver base, and a like plurality of mating conical sockets on the underface of a pallet, wherein a pallet is clamped down socket-topin by a clamp piston. The analogy may be made between the reference Patent referred to above and other similar types of "shot pin" locators which inject a conical tapered pin into a co-operating socket to locate one member with respect to another.

The problem inherent in utilizing such a mechanism forfinal registration of a pallet on a receiver base is that it is difficult to align the pins and sockets to level the pallet in a horizontal plane, and to locate the pins and sockets so they will not tend to fight one another for radial location with respect to the pin.

Additionally, it can be appreciated that as inevitable wear occurs, in one or more pin socket sets, the pallet will be tilted with respect to the horizontal plane and will tend to lose its alignment in respect of the desired relationship of a vertical stack of receiver base, pallet and workpiece.

A second prior art pallet registration apparatus is disclosed in U.S. Patent 3,543,392 in which the receiver base and the pallet underface are each fitted with one half of a multi-tooth facial coupling each having a plurality of conforming teeth. The separable coupling halves tend to minimize and distribute wear around the coupling teeth which tends to maintain the accuracy of the stack height and level attitude of the pallet with respect to the machine tool, but the facial array is expensive to produce and it is difficult to produce pallet coupling halves which mate equally alike with the receiver base coupling half.

It is an object of the present invention to provide a pallet registration mechanism that overcomes or minimises the above mentioned problems.

According to one aspect there is provided in or for a machine tool having a pallet receiver, clamping means to clamp a pallet thereon and release it therefrom to enable pallet interchange to be effected, registration apparatus for locating the pallet in mutually transverse first and second directions comprising:: (a) a first rigid locating surface on the receiver, (b) a second rigid locating surface on the pallet cooperative with said first surface to establish location in said first direction, (c) cooperative male and female elements, of which one at least is on said receiver and a cooperative one at least on said pallet and which interengage with each other by relative movement in said first direction to establish location in said second direction at a predetermined degree of interengagement, (d) compliant mounting means for supporting one at least of each cooperative ones of said elements whereby, after cooperation therebetween during relative movement in said first direction, relative movement between the pallet and receiver can be continued to bring about cooperation between said first and second locating surfaces to establish location in said first direction.

From a second aspect the invention resides in the provision of an improved pallet registration apparatus in a machine tool having a pallet interchanger; a pallet receiver with a base adapted to receive a pallet from said interchanger; and means to clamp and release said pallet at said receiver at selected interchange times, wherein the improvement comprises: (a) a first rigid locating surface on said receiver base; (b) a second rigid locating surface on said pallet; (c) a registration socket located on one of said pallet and receiver; (d) a registration pin matingly-shaped to said socket, located on the other of said pallet and receiver; and (e) compliant mounting means supporting one of said pin and said socket; wherein said pallet is moved and aligned through engagement of said pin and socket during a first portion of clamp means movement, and is subsequentlystationarily held and clamped through engagement of said first and second rigid surfaces during a second portion of clamp means movement.

Preferably the compliant mounting means comprises a diaphragm spring.

The male element or pin and the female element or socket preferably have respective tapering surfaces which cooperate to establish location in said second direction. Thus, the pin may have a conical tip and the socket may have a complementary conical bore.

Preferably the first and second locating surfaces are flat.

During a first portion of the clamp down movementthe pallet socket would engage the pin tip and during a second portion of the clamp down movement the pallet socket would deflect as permitted by way of its compliant mounting, e.g. through the diaphragm spring, to permit of engagement of the rigid locating surfaces of the pallet and the receiver ensuring accurate alignment by virtue of the rigid pin and socket cooperation and the rigid clamping of the pallet onto the locating surface of the receiver so that the pallet is able to withstand the machining forces. Any wear on the pin tip or mating socket would be compensated for by the deflectable com pliant support which carries the socket.

The invention will now be described by way of example with reference to the accompanying draw ings wherein :- Figure 1 is a perspective view of a machine tool employing the invention; Figure 2 is a plan view of the pallet receiver of Figure 1 taken in the direction of arrow 2 of Figure 1; Figure 3 is an elevational section taken through the pallet receiver taken along the line 3-3 of Figure 2.

Figure 4 is a section taken along the line 4-4 of Figure 2; Figure 5 is an alternate view of the elements of Figure 4 shown in the unclamped position; and Figure 6 is a view of the socket of Figure 5 taken along the line 6-6 of Figure 5.

Figure 1 of the drawings shows a machine tool 10 having a pallet interchange device 11 comprising a linearsideway 12 with a transport mechanism (not shown) for slidably presenting a pallet 13 to a pallet receiver 14 located in close proximity to a machine tool base 15.

The pallet interchange device could, alternatively, be a rotary mechanism or could be substituted for by a purely manual function.

The machine tool base carries (through horizontally and vertically slidable head parts) a cutter spindle 16 and a cutter 17 capable of providing a variety of machine tool operations to be performed on a workpiece (not shown). Workpieces are secured at a position off the machine to a variety of common pallets 13, which are selectably interchanged with each other as regards mounting on the pallet receiver 14.

The pallet receiver 14 has a receiver base 18 against which the pallet 13 is clamped and stationarily held with respect thereto during a machining operation on the workpiece. Here it may be noted that the receiver base 18 is shown circular and rotatable by a drive mechanism (not shown) with respect to a receiver sub-base 19 which is stationary with respect to the machine base 15. However, the receiver base 18 need not be rotatable and such rotation capability does not form part of the invention.

The receiver base 18 is provided with a plurality of locating wear pins 20 against which the bottomost edge 21 of the pallet clamp lip 22 is clamped during machining operations. While the wear pins 20 are shown as being separate from one another, it will be appreciated that a pair of pins 20 such as are shown in Figure 1 may be substituted for by a longitudinal wear strip having a similar cross-section and extending across the two pin bosses 23 parallel to the receiver slide 24. The receiver slide 24 is, of course, parallel to the interchange slide 12, in the sense that the pallet is guided for sliding by both for continuity of movement, as noted below, and is movable from a topmost position (shown) where the top surface 25 of the receiver slide 24 is level with the top surface 26 of the interchange slide 12 for receiving an oncom ing pallet 13.The receiver slide 24 is movable in a vertical direction so that after the pallet has been received on it the pallet clamp lip 22 is clamped down against the wear pins 20 of the receiver base 18. The mechanism for effecting this up and down movement will be described further in conjunction with the section view of Figure 3.

The plan view of Figure 2 illustrates the receiver base 18 having a plurality of bosses 23 provided thereon and which are machined and fitted with wear pins 20 to support a clamped pallet 13. The side edges 27,28 of the receiver slide 24 are parallel and of equal width to the interchange slide 12 so that a moving pallet 13 is ensured continuity of slide ways.

A pair of locating pins 29 are provided in the receiver base 18 which extend through seals 30 located in the receiver slide 24 and the locating pins 29 are oppositely disposed about the central vertical axis 31 of the receiver slide 24.

The section of Figure 3 taken through the vertical axis 31 of the receiver base 18 illustrates that the base 18 is generally comprised of a circular flanged bottom section 32 which blends to a main central portion 33 which is likewise circular. The central portion 33 has a bore 34 in which a close fitting piston 35 associated with the pallet, is situated. The bore 34 extends from the top surface 36 of the base 18 to a bottom surface 37 forming a shoulder within the piston bore 34. A second bore 38 is machined through the receiver base 18 from the bottomost surface 39 to the bottom surface 37 of the piston bore 34, to pilot the piston 35 received therein.The piston 35 has a central piston portion presenting a full diameter 40 fitted in the piston bore 34, and has oppositely extending end pilot portions 41,42, having reduced diameters extending respectively down through the second bore 38 and upward through a third bore 43 formed through a cylinder cap 44 which is received on the topmost surface 36 of the receiver base 18.

The cylinder cap 44 serves to encapsulate and limit upward movement of the piston 35 which is stopped against a pilot surface 45 formed on the cap 44 and which extends into the piston bore 34. Suitable hydraulic ports 46,47 are formed in the receiver base 18 and cylinder cap 44 to provide porting of hyd raulicfluidto raise and lowerthe piston 35. The upper pilot portion 42 of the piston 35 has a further pilot portion 48 of still further reduced diameter extending therefrom upon which is received the bore 49 of the receiver slide 24.

The receiver slide 24 is a generally rectangular plate about the central bore 49, and screws 50 are provided to secure the slide 24 to the piston 35. An annular skirt 51 is provided on the receiver slide 24 which extends down around the cylinder end cap 44 to act as a dust seal.

As shown in Figure 3, the pallet 13 is generally rectangular in cross-section having a slide recess 52 formed in its bottom surface 53, and a pair of clamp lips 22 are secured to the bottom surface 53 of the pallet 13 by screws 54, so that once slid into position on the receiver slide 24, the pallet 13 will be movable with the slide 24 in up or down directions. The clamp lips 22 extend along the bottom surface 53 of the receiver slide 24, and a slight clearance 55 exists between the top surface 25 of the slide 24 and the slide recess 52 in the pallet 13.

The receiver base 18 has a plurality of bosses 23 formed thereon, equally disposed about the central axis 31, and the bosses 23 have a suitable co-bore 56 machined therein to receive a pilot portion 57 of a pallet locating wear pin 20. The pallet locating wear pin 20 has a head 58 seated on the top surface 59 of the receiver base boss 23. The otherwise cylindrical head 58 of the pin 20 is relieved by way of a portion 60 so that only the portion 61 of the head 58 immediately under the receiver slide 24 will contact the clamp lip 22 of the pallet 13.

Figure 3 of the drawings shows the piston 35 in its clamped-position, wherein the receiver slide 24 is likewise forced to its lowest position, entrapping the clamp lip 22 of the pallet 13 against the wear pin 20.

- The section Figure 4taken through one of the locating pins 29 of Figure 2 illustrates that the locating pin 29 has a cylindrical flange 62 which is positioned against the top surface 63 of the special boss 64 provided on the receiver base 18, and the pin 29 has a main cylindrical portion 65 extending from the flange 62 and blending to a conical taper 66 at the end 67 of the pin 29. The main cylindrical portion 65 of the pin 29 extends through an elastomeric seal 68 which is secured in a counterbore 69 provided in the receiver slide by a seal retainer 70 and screws 71.

The counterbore 69 is concentric with a clearance bore 72 provided in the receiver slide 24 through which passes the locating pin 29.

The pallet 13 has a socket member 73 located in a counterbore 74 provided in its slide recess 52 and secured by pins 75 and screws 76. The socket member 73 has a thick cylindrical rim 77 which is thinned down to a central cylindrical web 78, which forms a diaphragm spring, relatively stiff in radial directions relative to the rim 77 yet axially movable and compliant with respect to the rim 77. The web 78 terminates at an interior socket portion 79, which has machined therein, a conical socket 80 which corresponds to the conical taper 66 of the locating pin 29.

Thus, it may be seen that when the pallet 13 is clamped in the downward direction by the pull of the receiver slide 24 against the clamp lip 22, the socket 80 will engage the locating pin 20 and establish accurate alignment of the pallet 13 about the pin 29 in radial directions.

In the view shown, the diaphragm web 78 is slightly stressed, though the deflection is imperceptible and generally has an available range in the nature of several thousandths of an inch (and a corresponding dimension expressed metrically) although only a portion is used. This is so that final vertical location of the pallet is established and maintained by the contact of the clamp lip 22 on the rigid locating surface 81 of the wear pin 20 and not dependent on the vertical positioning of the socket 80 on the pin 29. In this manner, the total stack height of the assembly, that is, the receiver base, pallet and workpiece, (not shown) may be maintained with respect to the machine tool.The downward clamp stroke of the piston 35 of Figure 3 accomplishes the engagement of the socket 80 and pin 29 in a first position of the downward stroke, and subsequently, the compliant pin socket 80 will permit the pallet 13 to be clamped down on the rigid wear pins 20 of the receiver base 18 during the final portion of the piston stroke.

Figure 5 illustrates the elements of Figure 4 in the upper position, wherein the top surface 25 of the receiver slide 24 is bearing against the slide recess 52 in the pallet 13, and the receiver surface 25 is aligned (in the horizontal plane) with the top end 67 of the locating pin 29. It can be seen therefore, that the elastomeric seal 68 of the receiver slide 24 will tend to hug the conical taper 66 of the pin 29 during the upward stroke, and the elastomeric seal 68 thus provides a closure about the end 67 of the pin 29 to prevent entry of contaminants to the critical locating taper 66 during pallet interchanges, when the top 67 of the pin 29 is exposed. -# The view of Figure 6 shows the socket member 73 and its respective cylindrical elements 77,78,79,80 wherein the member 73 is secured in the paller counterbore 74 by pins 75 and screws 76.

As previously stated in the description of Figure 1, the pair of wear pins 20 lying along a common side of the receiver slide 24 may be substituted for by a longitudinal bar having a cross-section as shown by the profile of the pinhead 58 of Figure 3 to provide a greater surface for wear distribution during the life of the pallet receiver 14.

It is not intended that the invention be limited to the specific embodiment shown herein, but rather the invention extends to all such designs and modifications as come within the scope of the appended claims.

Claims

1. In orfora machine tool having a pallet receiver, clamping means to clamp a pallet thereon and release it therefrom to enable pallet interchange to be effected, registration apparatus for locating the pallet in mutually transverse first and second directions comprising: (a) a first rigid locating surface on the receiver, (b) a second rigid locating surface on the pallet cooperative with said first surface to establish location in said first direction, (c) cooperative male and female elements, of which one at least is on said receiver and a cooperative one at least on said pallet and which interengage with each other by relative movement in said first direction to establish location in said second direction at a predetermined degree of interengagement, (d) compliant mounting means for supporting one at least of each cooperative ones of said elements whereby, after cooperation therebetween during relative movement in said first direction, relative movement between the pallet and receiver can be continued to bring about cooperation between said first and second locating surfaces to establish location in said first direction.

2. An improved pallet registration apparatus in a machine tool having a pallet interchanger; a paller receiver with a base adapted to receive a pallet from said interchanger; and means to clamp and release said pallet at said receiver at selected interchange times, wherein the improvement comprises: (a) a first rigid locating surface on said receiver base; (b) a second rigid locating surface on said pallet; (c) a registration socket located on one of said pallet and receiver; (d) a registration pin matingly-shaped to said socket, located on the other of said pallet and receiver; and (e) compliant mounting means supporting one of said pin and said socket; wherein said pallet is moved and aligned through engagement of said pin and socket during a first portion of clamp means movement, and is subsequently stationarily held and clamped through engagement of said first and second rigid surfaces during a second portion of clamp means movement.

3. The apparatus of either of claims 1 and 2 wherein said compliant mounting means comprises a diaphragm spring.

4. The apparatus of any one of the preceding claims wherein said first and second locating surfaces are flat

5. The apparatus according to any one of the preceding claims wherein the male element or pin and the female element or socket have respective tapering surfaces which cooperate to establish location in said second direction.

6. The apparatus of claim 5 wherein said pin has a conical tip and said socket has a complementary conical bore.

7. Apparatus according to any one of the preceding claims wherein the receiver comprises, a base presenting upwardly said first rigid locating surface, and also a plurality of said male elements or pins, said pallet presents said second rigid locating surface downwardly and has a plurality of said female elements or sockets each supported relatively to said pallet through said compliant mounting means which are sufficiently stiff with respect to movement parallel to said rigid surfaces to ensure accurate location in said second direction but which yield sufficiently in said first direction to allow said first and second locating surfaces to engage each other, the clamping means being so arranged as to effect relative movement between said pallet and said receiver to draw said pallet towards said receiver and bring about sequentially cooperation between said male elements or pins on the one hand and said female elements or sockets on the other hand and thereafter engagement of said first and second locating surfaces.

8. A pallet registration apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

9. A pallet registration apparatus including any novel feature or novel combination of features described herein and/or illustrated in the accompanying drawings.