METHOD AND APPARATUS FOR REPLACEMENT OF PALLETS USED IN A VERTICAL SPINDLE MACHINE TOOL FOR FASTENING OF WORKPIECES.

Abstract: Method and apparatus for replacement of pallets (8) used in a vertical-spindle machine tool for fastening of workpieces. The apparatus comprises a mobile pallet replacement trolley (9) which, for the period of pallet replacement, can be coupled fast with a bed (5), fitted with pallet fastening and positioning means. Said pallet replacement trolley (9) is provided with pallet replacement brackets, swingable around a horizontal axis for carrying pallets (8) from a machine tool (1) onto a pallet carrying trolley (10) or vice versa. The system facilitates the handling of pallets in a manner that the productive capacity of vertical-spindle working units can be substantially increased relative to necessary human labour.

Description: Method and apparatus for replacement of pallets used in a vertical spindle machine tool for fastening of workpieces. The present invention relates to a method for the re¬ placement of pallets used in a vertical spindle machine tool for fastening of workpieces, wherein a pallet to be replaced is fastened in a horizontal position between the fastening and positioning means mounted on a bed-on the machine tool table. The in¬ vention also relates to an apparatus for carrying out the method, said apparatus comprising a bed on the machine tool table, said bed being fitted with fasten¬ ing and positioning means for fastening a pallet there¬ between. Handling of pallets in various stages of operation as well as carrying them to various stages of operation require considerable human labour with respect to the capacity of a machine tool. This leads either to high labour costs or to machine tool operation on a reduced capacity, including long down times. This results in a longer redemption period of a machine tool investment. On the other hand, it is prior known to design a mach¬ ine tool with an automatic pallet replacement mechanism in which pallets are carried along fixed tracks. Such pallet replacement systems must be designed "tailor- made" for each type of machine tool, and in the prior art solutions, the costs of a pallet replacement system have become very high. Thus, the vertical-spindle tooling centres are nearly exclusively operated with¬ out automatic pallet replacement systems. It should be noted, however, that the mere replacement of pallets in a machine tool does not resolve the problems involved in handling pallets and workpieces. After the working, the pallets together, with machined workplaces' must be washed, the pieces must be measured and removed from a pallet and fresh pieces placed in a pallet for working. An object of the invention is to provide a pallet handling system, which not only facilitates handy and quick replacement of pallets in a machine tool but also adapts itself to handling of pallets in various stages of operation and to carrying pallets to various stages of operation. A method and apparatus of the invention for achieving this object is defined in the annexed claims. When operating an apparatus of the invention, the pieces to be worked can be fastened during working hours to a plurality of pallets, the apparatus of this invention facilitating the replacement of pallets in a machine tool even night time or during weekends either fully automatically or by employing temporary labour with no special skill required. Aside from fastening the workpieces to pallets, a single person at a time will be able to maintain the capacity of a machine tool at nearly 100 % by means of a method and apparatus of the invention. Moreover,, since the apparatus is relatively inexpensive in view of the price of a machine tool, the latter can be redeemed by means of an apparatus of the invention at a rate substantially more rapid than before. The invention will now be described in more detail with reference made to. the accompanying drawings, in which Figs. 1A - F illustrate the operation of. an. apparatus of. the invention in: various working stages. Figs. 2A - F are. schematical. views of various stages of operation of the apparatus in connection with a pallet replacement. Figs. 3A - C show a pallet replacement trolley in side, plan and end. view, respectively. Figs. 4A and B show a pallet carrying trolley in side and front view, respectively. Figs. 1A and 1B show a. vertical-spindle working unit 1 whose table 1a can be displaced in two directions per¬ pendicular to each other. A vertical spindle 1b, fitted with a tool, can be displaced in vertical direction. Mounted on table 1a is a rigid bed 5 whose one end is fitted with a rotary table 6 having its table section rota able around a horizontal axis,, the other end of bed 5 being fitted with a centering plug 7. A pallet 8 for fastening of workpieces is mounted between rotary table 6 and centering plug 7. By turning, said rotary table 6, pallet 8 can be rotated around its longitudinal axis quickly and accurately to any angular position. Thus, the tool can approach workpieces from different directions and a plurality of workpieces can be machined without having to remove and re-fasten a pallet in the meantime. In this regard, the present invention offers a pallet handling system for replac¬ ing pallets- in a machine tool and also for handling them in other working, stages outside a working unit as flexibly as possible, with small human labour force or fully automatically. Fig. 1 illustrates the replacement of a pallet. A separate mobile pallet, replacement trolly 9 is coupled fast with the edge of. bed 5. A pallet carrying trolley 10 is pushed inside said pallet replacement trolly 9 and linked therewith. The. swinging brackets mounted on pallet replacement trolly 9 take hold of a pallet delivered on carrying trolly 10 and by swinging the re¬ placing brackets said pallet is conveyed to the machine tool between rotary table 6 and centering plug 7 which, by means of e.g. pneumatic actuators, move the fasten¬ ing and positioning means into engagement with the ends of pallet 8. Also shown in fig. 1 is a separate carrying trolley 10, on which a pallet fitted with finished workpieces has been placed in the preceding stage of operation by means of pallet replacement trolley 9. Fig. 1B illustrates a situation where working unit 1 effects a work according.to a. program set therein on all workpieces mounted on pallet 8. Trolleys 9 and 10 are pushed aside for the working period so as not to block access to the working unit. Trolley 10,. on which a pallet fitted with finished workpieces is mounted, is then forwarded to desired further treatment steps. Fig. 1C shows a washing machine 2 for effecting the washing of a pallet and finishded pieces mounted on carrying trolley 10. Fig. 3D illustrates a measuring machine 3, in which a pallet and its associated workpieces can be placed from carrying trolley 10 by means of pallet replacement trolley 9.. In measuring machine 3, a .pallet is mounted and aligned between rotary table.6 and centering plug 1 , said rotary table 6. being used for determining ex- actly the. same positions for a pallet as in connection with working. In. addition, to measuring, also other auxiliary measures can be effected without removing the pieces from a pallet. Fig. 1E shows the replacement of workpieces into a pallet mounted on carrying trolley 10.. Fig. 1F shows a pallet, supply 4 into which pallets can be carried from carrying trolleys by means of pallet replacement brackets similar to those on pallet re¬ placement trolley 9. In minor workshops, such a pallet supply 4 is not necessary but, instead, pallets can be stored when mounted on carrying trolleys 10. Figs. 3A, B and C illustrate the design of a pallet re¬ placement trolley. The frame 9a of a trolley 9 is weld¬ ed of a square tube and supported on castors 9b for moving trolley 9 on the floor. On vertically adjust¬ able elements 34 is mounted a body, section 35 (Fig. 3C) , to which is journalled a member 11 pivotable around a horizontal axis. Connected integrally with member 11 are plate-like brackets 13, provided with two parallel and spaced slide bars 14. The direction of slide bars 14 is the same as that of the axis of rotation of member 11. Around slide bars 14 are mounted slides 15, slidable along said bars 14. Slide elements 15 are fitted with pallet replacement brackets 16, the pins at the ends thereof being engageable in the holes made in lugs 18 of pallet 8. Fixed to the. side edge of bed 5 on the working unit table are. attachment lugs 30, provided, with recesses for receiving guides 31 on trolley 9. By pushing a. shaft connected to. a hand knob 33,. plugs .32 can. be driven into, holes 32a in attach¬ ment lugs ' 30 (Figs. 3C and 3A) . A brake motor 12 swings through a reduction gear 12a said member. 11 together with its pallet replacement brackets 16. Operation of the apparatus is described in figs. 2A - 2F. In addition to the above-described design, between brackets 16 is fitted a double-action piston-cylinder device 17 and between one of the brackets (16) or its associated slide element 15 and member 11, 13 is a tension spring 19. At the ends of pallet 8 are fastening and positioning means 20 and 21 which fit in the corresponding fasten¬ ing and positioning means of rotary table 6 and center¬ ing plug 7. Figs. 2C, D and E illustrate an element 22, mounted on the rotatable table section of rotary table 6 and provided with a pull rod 24 driven by a piston- cylinder device 23, said pull rod gripping a pallet end element 20. The conical face 25 of element 22 effects centering with the corresponding conical face of element 20 and pins 26 entering the holes of element 20 prevent pallet 8 from rotating around its longitudin¬ al axis relative to element 22. Said centering plug 7 carries a centering point 27 driven by a piston- cylinder device 28, said point being engageable in the centering recess of end element 21 of pallet 8. In the outset situation shown in fig. 2A, pallet 8 is mounted on.a carrying trolley between fastening means 36 and 37. When carrying trolley 10 has been pushed inside pallet replacement trolley 9 and linked there¬ with as determined by fastening means, the holes in attachment lugs 18 of pallets 8 will be aligned with plugs 1.6a on brackets 16.- In order to facilitate this, brackets 16. are pulled away from each other by means of piston-cylinder device 17. Stoppers 14a at the ends of. slide bars 14 prevent slide elements 15 from slipping off. slide bars 14. Stoppers 14a at the right- hand end of slide bars 14 also take up ' the force exerted by spring 19 on a unit consisting of brackets 16, piston-cylinder device 17 and slide elements 15. Thus, stoppers 14a serve also as a limiter which de¬ termines the gripping position of brackets 16 and, thus, also the proper position, of pallet 8 relative to rotary table 6 and carrying trolley 10.. Fig. 2B shows a situation where piston-cylinder device 17 has been retracted for forcing brackets 16 into engagement with lugs 18 of pallet 8. Fig. 2C illustrates a situation where fastening means 36 and 37 of carrying trolley 10 are disengaged from end elements 20 and 21 and pallet 8 is ready to be placed in a machine tool. By driving motor 12 to turn member 11 together with its brackets 16 approximately 180°, pallet 8 will be conveyed to the position shown in fig. 2D between rotary table 6 and centering plug 7 in a machine tool. The table section of rotary table 6 is rotated into the position where pins 26 of said table-mounted element 22 find their way into the corresponding holes in end element 20. This is follow¬ ed by fastening and positioning of pallet 8 by retract¬ ing shaft 24 by means of piston-cylinder device 23 until conical face 25 is tightly pressed around the conical face of element 20. Piston-cylinder device 28 is used to push the centering point 27 into the centering recess of end element 21. Pallet will be fastened to a machine tool, as shown in fig. 2E. According, to fig. 2F, pallet replacement brackets 16 are. removed from pallet 8 by means of piston-cylinder device 17. Brackets 16 can now be returned in unload- ed condition to the position of fig. 2A and replacement trolley 9 is disengaged from bed 5. Removal of a pallet from a machine tool is effected by performing the above, stages of operation in reversed order, i.e. by coupling the replacement trolley with . bed 5, by fastening brackets 16 to the pallet lugs 18 (fig. 2E) , by disengaging fastening and positioning means 22-28 from pallet 8 (fig. 2D) , by swinging the disengaged pallet between the carrying trolley fasten¬ ing means 36 and 37 (fig. 2C) , by securing said carry¬ ing trolley fastening means 36 and 37 (fig. 2B) and by disengaging brackets 16 from a pallet (fig. 2A) , where¬ after the pallet carrying trolley together with its pallet and finished workpieces can be conveyed for further treatment. A carrying trolley shown in figs. 4A and 4B is a push cart fitted with castors. In this case, a pallet 8 can be mounted manually between fastening means 36 and 37. A carrying trolley 10 can also be made self-mobile, with steering effected e.g. along a magnetic pilot track. In this case, the replacement of a pallet can be effected in a fully automated fashion. The arrival and coupling of carrying trolley with a pallet replace¬ ment trolley activates a. state of readiness with pallet replacement actions beginning as soon as a machine tool provides an impulse indicating that the working is finished. Thus, the invention offers a universal pallet handling system, which, as such, is adaptable to various types of vertical--spindle working units.

Claims: Claims 1. A method for replacement of pallets (8) used in a vertical-spindle machine tool (1) for fastening work¬ pieces, wherein a pallet, to be replaced is fastened in a horizontal position, between fastening and positioning means (22-28) mounted on a bed (5) on a machine tool table (1a), c h a r a c t e r i z e d in that a separ¬ ate, mobile pallet replacement trolley (9) is coupled fast to said bed (5) , that pallet replacement brackets (16) on trolley (9) are brought to grip pallet (8) whose ends (20, 21) are gripped by fastening and positioning means (22-28) which are disengaged and, by swinging re¬ placement brackets (16) ' , said pallet (8) is carried onto a separate pallet carrying trolley (10) for con¬ veying a pallet to. various stages of treatment (fig. 1C, D, E, F) , and that said replacement brackets (16) are engaged with another pallet (8) on pallet, carrying trolley (10), the workpieces to be machined being fixed in this latter pallet (8) which, by swinging replace¬ ment brackets (16), is carried to a machine tool (1) between fastening and positioning means (22-28) , said pallet being fastened to the latter and pallet replace¬ ment trolley (9) being disengaged from bed (5). 2. A method as set forth in claim 1, c h a r a c t e r ¬ i z e d by the use of at least two pallet carrying trolleys (10), one of which being coupled with a pallet replacement trolley (9) for receiving a pallet (8) re¬ moved from machine (1), whereafter this first carrying trolley is pushed aside and the other carrying trolley (10), which carries a pallet (8) that has .the workpieces to be machined fixed, therein, is coupled with the pallet replacement, trolley (9) whose replacement brackets (16) are used to insert the pallet in machine (1). 3. An apparatus for carrying out the method of claim 1 , said apparatus comprising a bed (5) on the table .(.1a) of a machine tool (1) ,- said bed being fitted, with fast¬ ening and positioning means (22-28) for fastening a . pallet (8) therebetween, c h a r a c t e. r i z e d in that said apparatus comprises, a mobile pallet replace¬ ment trolley (9), separate from machine (1) and pro¬ vided with elements (30-32) for removably linking said trolley (9) to bed (5) , pallet replacement brackets (16), comprising power units (12, 17) for moving said brackets (16) and catch means (16a) for gripping a pallet (8) , and that, said apparatus further comprises a pallet carrying trolley (10), fitted with elements for removably linking, said carrying trolley (10) to pallet replacement trolley (9) , and fastening means (36, 37) for fastening pallet (8) to carrying trolley (10). 4. An apparatus as set forth in claim 3, c h a r a c t e r i z e d in that said apparatus comprises two or more carrying trolleys (10) for one pallet replacement trolley (9) . 5. An apparatus as set forth in claim 3, c h a r a c t e r i z e d in that, said pallet replace¬ ment brackets (16) are connected to a member (11, 13), journalled pivotably around a horizontal axis and adapted to be rotated by a motor (12) , and the horizontal distance between brackets (16) is adapted to be adjusted by a power unit (17). 6. An. apparatus as set forth in claim 5, c h a r a c t e r ! z- e d in that said pallet, replace¬ ment brackets (16) are connected to slide elements * (15) which, slide on horizontal slide bars (14), the latter being mounted on. said member (11,- 13) that- is journalled pivotably around a horizontal axis. 7. An apparatus as set forth in claim 6, c h a r a σ t e r i z e d in that between pallet re¬ placement brackets (16) or slide elements (15) is mounted a piston-cylinder device (17) and that between one of the brackets (16) and said member (11, 13) journalled pivotably around a horizontal axis is mounted a tension spring (19). 8. An apparatus as set forth in claim 3, c h a r a c t e r i z e d in that the edge of bed (5) is provided with fastening lugs (30) provided with re¬ cesses in which the guides (31) on pallet replace¬ ment trolley (9) are engaged and that trolley (9) is provided with locking elements (32) , adapted to en¬ gage with fastening lugs (30) for locking the move¬ ment of trolley (9) in driving direction. 9. An apparatus as set forth in claim 3, c h a r a c t e r i z e d in that said pallet replace¬ ment trolley (9) and pallet carrying trolley (10) can be pushed partially within each other. 10. An apparatus as set forth in claim 3, c h a r a c t e r i z e d in that said fastening and positioning means (22-28) on one hand consist of fast¬ ening and centering means (22-26) mounted on a rotary table (6) and on the other hand of a centering plug (7) catching one end of pallet (8) , said rotary table (6) and centering plug (7) being mounted on a common rigid bed (5) which in turn is mounted on the table (1a) of a machine tool (1).

Inventors: NIEMI PERTTI KALEVI, NIEMI, PERTTI, KALEVI
Applicants: KONTINO AB OY, OY KONTINO AB
Application year: 1985
Main classification: B23Q7
IPC codes: B23Q7