GB1586737A

GB1586737A - Closed loop machining system

Info

Publication number: GB1586737A
Application number: GB1373778A
Authority: GB
Original assignee: Kearney and Trecker Corp
Current assignee: Kearney and Trecker Corp
Priority date: 1977-04-08
Filing date: 1978-04-07
Publication date: 1981-03-25
Also published as: AU500428B1; JPS5714945B2; BE865785A; NL172623B; NL172623C; FR2386388A1; DE2814046A1; JPS53140682A; CH627680A5; FR2386388B1; CA1092333A; NL7803753A

Abstract

Three machine tools (10, 12, 14) are arranged at a distance from one another in a triangle. Each machine tool has a work table (22, 24, 26) which can slide along a horizontal axis and gradually about a vertical axis. Each work table has a guide device for accommodating a pallet (34) which carries one or more workpieces. One displacing unit (16, 18, 20) each for the workpieces is arranged respectively between adjacent machine tools and has a guide device for accommodating a pallet (34) and a hydraulically actuated slide which takes hold of the pallet and displaces it along the guide device from one machine tool to the adjacent machine tool. The loaded pallets are inserted into the loop at an operating station (46) and are transported in a controlled sequence to the next machine tool. The finish-machined workpieces are finally returned to the operating station, where they are then removed. The installation is compact and enables the workpieces to be fed and removed at a single operating station. <IMAGE>

Description

(54) CLOSED LOOP MACHINING SYSTEM (71) We KEARNEY & TRECKER COR- ORATION, a corporation organised and existing under the laws of the State of Wisconsin, United States of America, of 11000 Theodore Trecker Way, West Allis, Wisconsin, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a machining system. In the past, machine tools have been either stand-alone machines or part of an automated machining system. The automated machining systems include a group of machines along with a workpiece transport system for transporting workpieces from one machine to the next in the machining system and control means for synchronizing the operation of all of the machine tools and the workpiece transport system.

Automated machining systems are very efficient but require high capital investment while stand-alone machines are much lower both in terms of capital investment and efficiency. One bottle-neck for stand-alone machines is the problem of transferring workpieces on to the machine for machining and then transferring the finished workpiece to the next machine for the next machining operation. An object of this invention is to provide a simple machining system which solves the foregoing workpiece transfer problem but which is less expensive than the automated machining system heretofore known in the art.

In accordance with this invention there is provided a machining system which comprises at least three machine tools positioned in spaced apart relationship, each machine tool having a worktable slid ably mounted on a bed for movement along a horizontal axis, each worktable being indexable about a vertical axis, and each worktable having horizontal guide means for slidably receiving a workpiece support, and a plurality of workpiece transfer units each positioned to extend between two adjacent machine tools to transfer workpiece supports from the worktable of one machine tool to the worktable of the adjacent machine tool, each workpiece transfer unit having horizontal guide means for slidably receiving a workpiece support, and the guide means of each workpiece transfer unit being positioned to interact with the guide means of the worktables of the two adjacent machine tools, the machine tools and workpiece transfer units being arranged to form a closed loop around which workpiece supports may be transferred from one machine tool to another all the way around the loop.

An operator's station may be provided at one of the workpiece transfer units for introducing unmachined workpieces into the loop and removing machined workpieces from the loop. The unmachined workpieces introduced into the loop at the operator's station are transferred from one machine tool to the next around the loop for machining and eventually return to the operator's station for unloading.

In the accompanying drawings: Figure 1 is a plan view of a preferred embodiment of the invention; Fig. 2 is a plan view of one machine tool and the adjacent workpiece transfer units with the pallet on the machine tool worktable being in position to be transferred off the machine tool worktable; Fig. 3 is a plan view similar to Fig. 2 but with the machine tool worktable empty and positioned to receive a new pallet.

Fig. 4 is a side elevation view, partially cut away, of one workpiece transfer unit; Fig. 5 is a fragmentary end elevation view of the workpiece transfer unit shown in Fig. 4; Fig. 6 is a fragmentary longitudinal sectional view taken on the line 6-6 of Fig.

5; and Fig. 7 is a diagrammatic perspective view showing the cables and hydraulic cylinders which move the workpiece transfer slide.

Figure 1 is a plan view of a preferred embodiment of the invention which includes three machine tools 10, 12, and 14 and three workpiece transfer units 16, 18, and 20 arranged in a closed loop which in this particular case is triangular in shape but which could be any suitable polygon depending on the number of machine tools employed. Each of the machine tools 10, 12 and 14 has a corresponding worktable 22, 24, and 26 which is slidably mounted on a corresponding bed 28, 30 and 32. Each of the worktables 22, 24 and 26 is slidably along a horizontal axis and is indexable about a vertical axis. Each worktable 22, 24 and 26 has horizontal guide means to slidably receive a pallet 34 carrying one or more workpieces 36, 38 and to clamp the pallet 34 thereon so that the workpieces 36, 38 can be machined by the machine tools 10, 12 and 14.

Workpiece transfer units 16, 18 and 20 each extend between two adjacent machine tools 10, 12, and 14 and are positioned on the sides of the triangle defined by machine tools 10, 12 and 14. Workpiece transfer units 16, 18 and 20 are positioned to interact with worktables 22, 24, and 26 in transferring pallets 34 from one worktable 22, 24, 26 to an adjacent worktable 22, 24, 26.

To transfer a pallet 34 off one of the worktables 22, 24, 26, the worktable is moved along its bed to a location opposite the end of the appropriate workpiece transfer unit 16, 18, 20 as shown in Fig. 2 and is indexed about its vertical axis until the worktable pallet ways 40 (Fig. 3) are aligned with the corresponding transfer unit pallet ways 42 (Fig. 2) so that the pallet 34 can be slid off of the worktable and on to the transfer unit. Fig. 2 shows the relative positions required to slide the pallet 34 off of worktable 24 and on to the transfer unit 18.

After the pallet 34 is slid off of worktable 24, the worktable 24 is indexed to align its pallet ways 40 with the pallet ways 44 of the transfer unit 16 as shown in Fig. 3 so that it can receive another pallet 34 from transfer unit 16. In this particular example, the flow of pallets 34 is counter-clockwise in Fig. 1, although pallet flow in the opposite direction is equally feasible since the workpiece transfer units 16, 18 and 20 are adapted to move the pallets 34 in either direction.

Pallets 34 are introduced into the closed loop system at an operator's station in the middle of transfer unit 16. An operator 46 places a pallet 34 carrying workpieces 36 and 38 on the transfer unit 16 with conventional lifting devices (not shown). The pallet 34 is subsequently transferred counterclockwise around the loop first to the machine tool 12, then to the machine tool 14, then to the machine tool 10, being machined at each machine tool. After all the machining has been completed, pallet 34 is returned to the operator's station on the transfer unit 16 where it is removed by the operator 46 and replaced by a pallet carrying unmachined workpieces. Alternatively, only the workpieces 36 and 38 could be removed and replaced at the operator's station.

In this particular example, the machine tools 12 and 14 are horizontal machining centres while the machine tool 10 is a multiplespindle indexable turret. However, it will be understood by those skilled in the art that any combination of machine tools can be employed which have indexable worktables adapted to interact with workpieces transfer units to transfer on to and off of the worktables.

The construction of the workpiece transfer units 16, 18 and 20 is illustrated in Figs. 4 to 7. Referring to Figs. 4 and 5, each transfer unit 16, 18 and 20 comprises a bed 48 which is supported by legs 50. A pair of spaced horizontal guide means or pallet ways 52 and aligned rollers 53 are supported on top of bed 48 for slidably receiving a pallet 34. A transfer slide 54, best shown in Fig. 7, is slidably mounted on rails 56 (Fig. 7) that extend the full length of the bed 48. The transfer slide 54 carries a pair of extendable and retractable vertical posts 58 and 60 which are cylindrical in shape and are slotted on their upper end at 59 and 61 to engage lugs 62 on the pallets 34 as best shown in Fig. 7. In Fig. 7, the post 58 is shown in its extended position engaging lug 62 while post 60 is shown in its retracted position below the level of lug 62.

In Fig. 4, the post 60 is in the extended position engaging lug 62 while post 58 is in the retracted position. The post 60 is used to pull pallets 34 on to the transfer unit and the post 58 is used to push pallets off of the transfer unit as described below.

The posts 58 and 60 are moved upwardly and downwardly between their extended and retracted positions by slidable cam plates 64 (Fig. 5) which extend transverse to posts 58 and 60 and have sloping cam slots 66 therein which engage cam rollers 68 attached to the bottom of posts 58 and 60, as best shown in Fig. 6 for post 60. Post 60 is notched at 70 (Fig. 6) to provide clearance for cam plate 64. Cam roller 68 is attached to the notched end of post 60 by a machine screw 72 and rides in cam slot 66 of cam plate 64. A similar mounting is used for the cam plate 64 and cam roller 68 on the bottom of post 58.

The posts 58 and 60 are raised by moving their cam plates 64 to the left in Fig. 5 to the position shown therein and are lowered by moving their cam plates 64 to the right in Fig. 5. The movement of cam plates 64 is caused by pairs of hydraulic cylinders 74 and 76 (Fig. 5) mounted on bed 48 and positioned opposite the locations where the pallet lugs 62 are to be engaged. The cylinders 74 and 76 move plungers 78 and 80, respectively, against the side edges of cam plates 64 when actuated to move cam plates 64 either to the left or to the right in Fig. 4, thereby either raising or lowering the corresponding post 58 or 60. The cylinders 74 and 76 are double-acting cylinders which are caused to extend or retract their plungers 78 and 80 by conventional control means which is not shown in the drawings. The cylinders 74 and 76 are actuated in paired opposition, i.e., when one plunger 78, 80 is extended the other is retracted and vice versa. Conventional limit switches 82 and 84 are mounted opposite the cylinders 74 and 76 and interact with bumpers 86 and 88 on the outer ends of the plungers 78 and 80 to indicate whether the plungers 78 and 80 are in their extended or retracted position. The limit switches 82 and 84 provide information for the transfer control means.

When the cam plates 64 are moved to the left in Fig. 4 to raise post 58 or 60 to the extended position, roller 68 enters a horizontal portion 90 (Fig. 5) of cam slot 66 at the upper end thereof which holds the corresponding post 58 or 60 in its extended position as transfer slide 54 is moved back and forth along bed 48.

Transfer slide 54 is moved by a hydraulically driven cable arrangement which is illustrated schematically in Fig. 7.

A first cable 92 is attached to one end of transfer slide 54 and passes around a first fixed pulley 94 which is rotatably attached to transfer unit bed 48 and then passes around a movable pulley 96 which is rotatably attached to the plunger 98 of a hydraulic cylinder 100. Cylinder 100 is rigidly attached to transfer unit bed 48.

After passing around movable pulley 96, cable 92 is attached to a bracket 102 on transfer unit bed 48.

On the other side of transfer slide 54, a second cable 104 is attached thereto and passes around a fixed pulley 106 which is rotatably attached to transfer unit bed 48 and then passes around a movable pulley 108 which is rotatably attached to the plunger 110 of a second hydraulic cylinder 112. Cylinder 112 is rigidly attached to transfer unit bed 48. After passing around movable pulley 108, cable 104 is attached to a bracket 114 on transfer unit bed 48.

Hydraulic cylinders 100 and 112 are both double-acting and are actuated in paired opposition to cause transfer slide 54 to move along transfer unit bed 48, i.e., when one of the hydraulic cylinders 100, 112 is retracted, the other is extended by the same amount, and vice versa. Hydraulic cylinders 100 and 112 are operated by conventional control means which is not shown in the drawings.

To draw a pallet 34 on to the transfer unit, transfer slide 54 is moved to the end of transfer unit bed 48 adjacent to pallet 34 as shown in Fig. 4. Hydraulic cylinders 74 and 76 are then actuated to raise post 60 and engage it with lug 62. The hydraulic cylinders 100 and 112 are then actuated to draw pallet 34 on to and across the transfer unit. When transfer slide 54 reaches the other end of the transfer unit, post 60 is lowered and transfer slide 54 is repositioned to place post 58 under the lug 62 at the other end of pallet 34. Post 58 is then raised to engage lug 62 and transfer slide 54 is moved to push pallet 34 off the transfer unit. The pallet 34 is drawn on to the transfer unit by post 60 and is pushed off by post 58. However, if desired, the direction of transfer can be reversed, and if so the pallet 34 will be drawn on to the transfer unit by post 58 and will be pushed off by post 60.

The hydraulic control means which cause the above described movements of transfer slide 54 and posts 58 and 60 is conventional and hence is not shown in the drawings.

WHAT WE CLAIM IS: 1. A machining system which comprises at least three machine tools positioned in spaced apart relationship, each machine tool having a worktable slidably mounted on a bed for movement along a horizontal axis, each worktable being indexable about a vertical axis, and each worktable having horizontal guide means for slid ably receiving a workpiece support, and a plurality of workpiece transfer units each positioned to extend between two adjacent machine tools to transfer workpiece supports from the worktable of one machine tool to the worktable of the adjacent machine tool, each workpiece transfer unit having horizontal guide means for slidably receiving a workpiece support, and the guide means of each workpiece transfer unit being positioned to interact with the guide means on the worktables of the two adjacent machine tools, the machine tools and workpiece transfer units being arranged to form a closed loop around which workpiece supports may be transferred from one machine tool to another all the way around the loop.

2. A system according to claim 1, wherein the machine tools and workpiece transfer units are positioned in a polygonal pattern.

3. A system according to claim 1 or 2, wherein each workpiece transfer unit includes means for pulling a workpiece support on to the transfer unit from one adjacent worktable and for pushing the workpiece support off of the transfer unit and on to the other adjacent worktable.

4. A system according to claim 3,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cylinders 74 and 76 move plungers 78 and 80, respectively, against the side edges of cam plates 64 when actuated to move cam plates 64 either to the left or to the right in Fig. 4, thereby either raising or lowering the corresponding post 58 or 60. The cylinders 74 and 76 are double-acting cylinders which are caused to extend or retract their plungers 78 and 80 by conventional control means which is not shown in the drawings. The cylinders 74 and 76 are actuated in paired opposition, i.e., when one plunger 78, 80 is extended the other is retracted and vice versa. Conventional limit switches 82 and 84 are mounted opposite the cylinders 74 and 76 and interact with bumpers 86 and 88 on the outer ends of the plungers 78 and 80 to indicate whether the plungers 78 and 80 are in their extended or retracted position. The limit switches 82 and 84 provide information for the transfer control means. When the cam plates 64 are moved to the left in Fig. 4 to raise post 58 or 60 to the extended position, roller 68 enters a horizontal portion 90 (Fig. 5) of cam slot 66 at the upper end thereof which holds the corresponding post 58 or 60 in its extended position as transfer slide 54 is moved back and forth along bed 48. Transfer slide 54 is moved by a hydraulically driven cable arrangement which is illustrated schematically in Fig. 7. A first cable 92 is attached to one end of transfer slide 54 and passes around a first fixed pulley 94 which is rotatably attached to transfer unit bed 48 and then passes around a movable pulley 96 which is rotatably attached to the plunger 98 of a hydraulic cylinder 100. Cylinder 100 is rigidly attached to transfer unit bed 48. After passing around movable pulley 96, cable 92 is attached to a bracket 102 on transfer unit bed 48. On the other side of transfer slide 54, a second cable 104 is attached thereto and passes around a fixed pulley 106 which is rotatably attached to transfer unit bed 48 and then passes around a movable pulley 108 which is rotatably attached to the plunger 110 of a second hydraulic cylinder 112. Cylinder 112 is rigidly attached to transfer unit bed 48. After passing around movable pulley 108, cable 104 is attached to a bracket 114 on transfer unit bed 48. Hydraulic cylinders 100 and 112 are both double-acting and are actuated in paired opposition to cause transfer slide 54 to move along transfer unit bed 48, i.e., when one of the hydraulic cylinders 100, 112 is retracted, the other is extended by the same amount, and vice versa. Hydraulic cylinders 100 and 112 are operated by conventional control means which is not shown in the drawings. To draw a pallet 34 on to the transfer unit, transfer slide 54 is moved to the end of transfer unit bed 48 adjacent to pallet 34 as shown in Fig. 4. Hydraulic cylinders 74 and 76 are then actuated to raise post 60 and engage it with lug 62. The hydraulic cylinders 100 and 112 are then actuated to draw pallet 34 on to and across the transfer unit. When transfer slide 54 reaches the other end of the transfer unit, post 60 is lowered and transfer slide 54 is repositioned to place post 58 under the lug 62 at the other end of pallet 34. Post 58 is then raised to engage lug 62 and transfer slide 54 is moved to push pallet 34 off the transfer unit. The pallet 34 is drawn on to the transfer unit by post 60 and is pushed off by post 58. However, if desired, the direction of transfer can be reversed, and if so the pallet 34 will be drawn on to the transfer unit by post 58 and will be pushed off by post 60. The hydraulic control means which cause the above described movements of transfer slide 54 and posts 58 and 60 is conventional and hence is not shown in the drawings. WHAT WE CLAIM IS:

1. A machining system which comprises at least three machine tools positioned in spaced apart relationship, each machine tool having a worktable slidably mounted on a bed for movement along a horizontal axis, each worktable being indexable about a vertical axis, and each worktable having horizontal guide means for slid ably receiving a workpiece support, and a plurality of workpiece transfer units each positioned to extend between two adjacent machine tools to transfer workpiece supports from the worktable of one machine tool to the worktable of the adjacent machine tool, each workpiece transfer unit having horizontal guide means for slidably receiving a workpiece support, and the guide means of each workpiece transfer unit being positioned to interact with the guide means on the worktables of the two adjacent machine tools, the machine tools and workpiece transfer units being arranged to form a closed loop around which workpiece supports may be transferred from one machine tool to another all the way around the loop.

4. A system according to claim 3,

wherein the means for pulling workpiece supports on to and pushing workpiece supports off of said workpiece transfer unit comprises a transfer slide slidably mounted on the workpiece transfer unit for horizontal movement from one end of the transfer unit to the other, a pair of vertical posts movably mounted on the transfer slide for movement between a raised and a lowered position, means on the posts for engaging the workpiece supports, and means for selectively raising the posts to engage said workpiece supports and for selectively lowering the posts to disengage them from the workpiece supports.

5. A system according to claim 4 wherein the means for selectively raising and lowering the posts comprises a cam roller attached to each post, a cam plate for each post, each cam plate being slidable transverse to the corresponding post and having a cam slot therein shaped to engage the cam roller and to raise or lower the post when said cam plate is moved transverse to the post, and means for selectively moving each of the cam plates transverse to the corresponding post to raise and lower the posts.

6. A system according to claim 5, wherein the means for selectively moving the cam plates transverse to the posts comprises a Ipair of hydraulic cylinders mounted on opposite sides of the cam plate, each hydraulic cylinder having a plunger positioned to contact the cam plate and move it in one direction transverse to the corresponding post.

7. A system according to claim 3, wherein the means for pulling workpiece supports on to and pushing workpiece supports off of the workpiece transfer unit comprises a transfer slide slidably mounted on the workpiece transfer unit for horizontal movement from one end of the transfer unit to the other, means on the transfer slide for selectively engaging the workpiece supports, a first cable attached at one end to the transfer slide and attached at the other end to the transfer unit, a first hydraulic cylinder having an extend able and retractable plunger, a first pulley on the end of the retractable plunger, the first cable passing over said first pulley, a second cable attached at one end to the transfer slide opposite the first cable and attached at the other end to the transfer unit, a second hydraulic cylinder having an extendable and retractable plunger, and a second pulley on the end of the plunger, the second cable passing over the second pulley.

8. A machining system substantially as herein described with reference to the accompanying drawings.