Tool changer for machine tools

Abstract: The invention provides a tool changer for machine tools capable of transferring a tool transfer pot with a stroke smaller than the transfer distance of the tool transfer pot. In a tool changer 20 for a combined machining lathe (machine tool) 1 comprising: a tool magazine 21 on which a multiplicity of tools T are loaded and which serves for transferring and indexing a next-process tool T1 to a specified tool takeout position P1; a tool transfer mechanism 23 for taking out and transferring the next-process tool T1 positioned in the tool takeout position P1 to a tool changing position P3; and a tool changing mechanism 24 for changing a process-completed tool T0 loaded on a tool post body 11 with the next-process tool T1 positioned in the tool changing position P3, wherein the tool transfer mechanism 23 is made up of a transfer arm 49 disposed pivotable between the tool takeout position P1 and the tool changing position P3, a tool transfer pot 26 coupled to a front end portion of the transfer arm 49 and serving for supporting the next-process tool T1, and an air cylinder coupled to the transfer arm 49 and serving for pivotally driving the transfer arm 49.

Description: BACKGROUND OF THE INVENTION The present invention relates to a tool changer for machine tools, the tool changer being equipped with a tool transfer mechanism which transfers a next-process tool that has been transferred to a specified tool takeout position by a tool magazine, between the tool takeout position and a tool changing position. In some tool changers, there is a distance between the tool changing position, which is set near the tool spindle, and the tool takeout position for the next-process tool, which is set to the tool magazine. In such a case, generally, the tool changer is equipped with a tool transfer mechanism for transferring the next-process tool from the tool takeout position to the tool changing position. As an example of such tool transfer mechanisms, there has been provided hitherto a tool transfer mechanism having an air cylinder mechanism which moves back and forth over a range from the tool takeout position to the tool changing position, where a piston rod of the air cylinder mechanism is equipped with a tool pot for holding the next-process tool, the tool pot being linearly transferred between the tool takeout position and the tool changing position by the piston rod. From GB-A-1 283 584 there is known a tool changer for machine tools comprising: a tool magazine on which a multiplicity of tools are loaded and which serves for transferring and indexing a next-process tool to a specified tool takeout position; a tool transfer mechanism for taking out and transferring the next-process tool positioned in the tool takeout position to a tool changing position and a tool changing mechanism for changing a tool loaded on a tool post with the next-process tool positioned in the tool changing position, wherein the tool transfer mechanism comprises: a transfer arm disposed pivotable between the tool takeout position and the tool changing position; and a cylinder mechanism coupled to the transfer arm and serving for pivotally driving the transfer arm. However, this conventional tool transfer mechanism involves providing a large-scale air cylinder mechanism having a stroke equal to or larger than the transfer distance of the tool pot. This would pose a problem of increased installation space. The present invention having been accomplished in view of these and other problems of the prior art, an object of the invention is to provide a tool changer for machine tools capable of transferring the tool pot with a stroke smaller than the transfer distance of the tool pot. In order to achieve the above object, the present invention provides a tool changer for machine tools according to claim 1. In an embodiment, the present invention provides a tool changer for machine tools as described above, wherein an engaging groove extending in a tangential direction is formed in a tool transfer pot serving for holding the tool, and the tool holding member has a guide pin which engages with the engaging groove to thereby position and support the tool transfer pot in axial and circumferential directions. According to the tool changer of the present invention, the transfer arm pivotable between the tool takeout position and the tool changing position is provided, the tool holding member is provided at the front end portion of the transfer arm, and the cylinder mechanism for pivotally driving the transfer arm is coupled to the transfer arm. Therefore, the tool holding member can be transferred from the tool takeout position to the tool changing position with a stroke smaller than the travel distance of the tool holding member, thus producing effects that the cylinder mechanism can be downsized proportionally and moreover that the installation space therefor can be reduced. In an embodiment, the engaging groove is formed in the tool transfer pot and the tool holding member is provided with the guide pin to engage with the engaging groove. Therefore, in holding the tool transfer pot by the tool holding member, the tool transfer pot can be positioned in the axial and circumferential directions with reliability and moreover transferred to the tool changing position in the positioned state, thus producing an effect that the positioning accuracy of the cutting tool can be ensured in loading the next-process tool onto the tool spindle. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a right side view of a combined machining lathe equipped with the tool changer according to an embodiment of the present invention; Fig. 2 is a front view of the combined machining lathe; Fig. 3 is a right side view of the tool post of the combined machining lathe; Fig. 4 is a front view of the tool changer; Fig. 5 is a right side view showing the overall construction of the tool changer; Fig. 6 is a schematic rear view of the turn and transfer mechanism of the tool changer; Fig. 7 is a plan view showing the positioning state of the tool transfer pot of the tool changer; Fig. 8 is a sectional view showing the positioning state of the tool transfer pot; and Fig. 9 is a side view showing a tool changer according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinbelow, an embodiment of the present invention is described with reference to the accompanying drawings. Figs. 1 to 8 are views for explaining a tool changer for use in a combined machining lathe (machine tool) according to an embodiment of the invention. More specifically, Figs. 1 and 2 are right side view and a front view of a combined machining lathe equipped with the tool changer, Fig. 3 is a right side view of the tool post, Fig. 4 is a front view of the tool changer, Fig. 5 is a right side view showing the overall construction of the tool changer, Fig. 6 is a rear view of the turn and transfer mechanism, and Figs. 7 and 8 are a plan view and a sectional view, respectively, showing the positioning state of the tool transfer pot. Referring to the figures, reference numeral 1 denotes a combined machining lathe capable of performing both turning and rotating-tool machining. Roughly referring to the construction of this combined machining unit 1, on top of a fixed bed 2, a headstock 7 is fixedly disposed at a left side end portion as viewed from the front, while a saddle 4 is disposed on the right side as viewed in the right side face so as to be movable in a Z-axis (a direction vertical to the sheet of Fig. 1) parallel to the axis of the headstock 7 via two linear guides 3a, 3a. On top of the saddle 4, a column 5 is disposed so as to be movable in a direction within a horizontal plane and perpendicular to the axis of the headstock 7 via two linear guides 3b, 3b. Moreover, a tool post 6 with a tool T fitted thereto is disposed on the column 5 so as to be movable within a plane along a sloping surface 5a of the column 5 and in an X-axis direction perpendicular to the axis of the headstock 7. A main spindle (not shown) equipped with a chuck 8 for gripping a workpiece is provided on the headstock 7, and this main spindle is rotationally driven by a spindle motor (not shown). In addition, reference numeral 1a denotes a door for opening and closing an access opening formed in an unshown cover. As to the structure of the tool post 6, roughly, a support base 9 is disposed on the forwardly-declined sloping surface 5a (slope angle: 60 degrees) of the column 5 so as to be slidable in the X-axis direction, and a tool post body 11 is supported on the support base 9 so as to be rotationally indexable and clampable about a turning axis A perpendicular to the sloping surface 5a by means of a rotationally indexing device 10. The tool post body 11 comprises a tool spindle 14 in which the tool T is removably fitted at its front end portion, a tool spindle head 12 for rotatably supporting the tool spindle 14, and a tool spindle motor 13 which is placed within the tool spindle head 12 and which drives the tool spindle 14 into rotation. The rotationally indexing device 10 comprises a rotating table 16 fixedly bolted to the tool post body 11, a fixing table 17 which is disposed within the rotating table 16 so as to be coaxial therewith and which is fixedly bolted to the support base 9, a rotation driving mechanism 18 for rotationally driving the rotating table 16 to a specified indexing angular position about the turning axis A, and a coupling mechanism 19 which fixes the rotating table 16 to the indexing angular position of the fixing table 17. With the tool post body 11 fixed in the indexing angular position, lathe turning or milling is performed. The combined machining lathe 1 has a tool exchanger 20. This tool exchanger 20, on which a multiplicity (60 to 180) tools T are loaded, comprises: a tool magazine 21 for transferring, indexing and positioning a next-process tool T1 to a tool takeout position P1; a tool turning/transferring mechanism 22 for taking out the next-process tool T1 positioned to the tool takeout position P1 and turning and transferring it to a delivery position P2; a tool transfer mechanism 23 for transferring the next-process tool T1, which has been transferred to the delivery position P2, to a tool changing position P3; and a tool changing mechanism 24 for replacing a process-completed tool T0 loaded on the tool spindle 14 with the next-process tool T1 transferred to the tool changing position P3. It is noted that at a tool change, the process-completed tool T0 is positioned to the changing position by turning the tool post body 11 in the direction vertical to the sheet of Fig. 1 about the turning axis A by the rotationally indexing device 10. The tool magazine 21 is located on the fixed bed 2 and behind (in the rear of) the tool post 6, and supported by a magazine support base 25 fixedly bolted to a rear side wall 2a of the fixed bed 2. This tool magazine 21 is so constructed that a multiplicity of tool transfer pots 26 for holding the tool T1 on an endless transfer chain 21b wound around a driving sprocket 21a are removably attached at a specified pitch, and that the endless transfer chain 21b is driven by a turn driving motor. The tool takeout position P1 is so set as to be positioned on a line that connects the tool delivery position P2, the tool changing position P3 and the process-completed tool T0 indexed to the changing position, as viewed in the right side face, where these positions P1 to P3 are set generally flush with one another. As a result of this, the transfer amount of the next-process tool T1 is reduced. The tools T are removably fitted to the individual tool transfer pots 26 of the tool magazine 21, and each tool T is placed so as to be positioned within a horizontal plane and toward a direction perpendicular to the axis of the headstock 7 (Z-axis direction). The tool T has a cutting tool 28 fitted to a cylindrical-shaped tool holder 27 which is held by the tool transfer pot 26. The tool changing mechanism 24 is so constructed that a changing shaft 31 is axially movably and rotatably supported by a support member 30 provided erect at a left end portion of the saddle 4 as viewed from the front, and that a changing arm 32 is fixed to a front end portion of the changing shaft 31. In this changing arm 32, cutouts 32a, 32a for holding the tool holder 27 are formed at both ends of a band-shaped plate. In the support member 30, a drive mechanism 30a which drives the changing shaft 31 into rotation and moreover into reciprocation in the axial direction is provided. The changing shaft 31 is so constructed that an axially moving cylinder 31b is fitted to a rotating shaft 31a so as to be axially movable and rotatable integrally therewith, and the changing arm 32 is fixed to a front end portion of the axially moving cylinder 31b. In Fig. 4, a portion of the changing shaft 31 upper than the axis B shows a state that the changing shaft 31 has moved forward so that a tool is fitted to the tool spindle 14, while the lower portion shows a state that the changing shaft 31 has moved backward so that a tool is pulled out from the tool spindle 14. The tool turning/transferring mechanism 22 has the following structure. A takeout opening 25b is formed at a portion of an upper wall 25a of the magazine support base 25 confronting the tool takeout position P1, and a piston rod 36 of a cylinder mechanism 35 is advanceably and retreatably opposed to the takeout opening 25b. This cylinder mechanism 35 is rotatably held between a position confronting the tool takeout position P1 and a position rotated 90 degrees from the position about a turning axis C, by means of a bracket 38 mounted on the top of the upper wall 25a. The bracket 38 is provided with an unshown turn driving mechanism. The piston rod 36 is equipped with a generally U-shaped gripping member 37 and a presser pin 39. The presser pin 39 is biased axially movably and downward with an unshown spring. By pressing upper part of the tool transfer pot 26 with the presser pin 39, the tool transfer pot 26 is gripped in cooperation with the gripping member 37. When the piston rod 36 goes down, the gripping member 37 and the presser pin 39 move to a position where a tool transfer pot 26 of the next-process tool T1 is to be gripped. In this state, a required tool transfer pot 26 is indexed to the tool takeout position P1, and with the required tool transfer pot 26 held by the gripping member 37 and the presser pin 39, the piston rod 36 goes up. At an upper end position of this up, the cylinder member 35 turns 90 degrees about the turning axis C, and subsequently the piston rod 36 goes down. As a result, the next-process tool T1 is turned and transferred to the tool delivery position P2 so as to be parallel to the axis of the headstock 7. The tool transfer mechanism 23 is constructed as follows. A transfer support base 45 is vertically provided and fixed between the column 5 on top of the saddle 4 and the changing arm 32. This transfer support base 45 is formed into a generally box shape which extends upward while bending rightward as shown in Fig. 4, and which has a side wall portion 45b integrally and erectly formed at a peripheral edge portion of its vertical wall portion 45a that is wide in the back-and-forth direction as viewed from the front, where a guide plate 46 is fixedly bolted at an upper end portion of the vertical wall portion 45a. This guide plate 46 is formed into a band shape extending horizontally over a range from the tool delivery position P2 to the tool changing position P3. On the left side face of the guide plate 46, is fixed a rail 47a of a linear guide 47 which extends linearly between the two positions P2, P3, where a block 47b is slidably engaged with the rail 47a with balls (not shown) interposed therebetween. A pivot shaft 48 is fixedly bolted at a lower end portion of the vertical wall portion 45a, and a boss 51 fixed at the lower end of a transfer arm 49 is pivotably fitted to the pivot shaft 48 via a bearing 50. This transfer arm 49 is so constructed that a band-shaped upper half portion 49b is fixedly bolted to a generally rectangular-cylindrical lower half portion 49a, and the upper end of the upper half portion 49b is supported to the block 47b via a cam mechanism 53. The cam mechanism 53 is so constructed that a cam plate 54 with a cam groove (not shown) formed therein is fixed to the block 47b, and that a cam follower 55 to be engaged with the cam groove of the cam plate 54 is attached to the upper half portion 49b. Pivotal motion of the transfer arm 49 is transformed into linear motion of the linear guide 47 by the cam mechanism 53. Also, a piston rod 57 of an air cylinder 56 disposed with its axis directed along the back-and-forth and horizontal direction is coupled to a proximity of the pivot shaft 48 of the transfer arm 49. The transfer arm 49 is pivotally driven between the delivery position P2 and the tool changing position P3 by expansion and contraction of the piston rod 57. The air cylinder 56 is up-and-down swingably supported by a bracket 59 via a pivot shaft 58, and the bracket 59 is secured to the side wall portion 45b. The air cylinder 56 swings up and down on a fulcrum of this pivot shaft 58, thereby allowing the piston rod 57 to linearly move. A pot holding member (tool holding member) 60 is fixedly connected to an upper end portion of the block 47b. This pot holding member 60 has a structure, roughly, that four guide pins 62 are implanted on a support plate 61. Each of these guide pins 62 is so structured that a sloping guide portion 62c is formed at an upper end portion of a prismatic pin body 62a. One set of engaging grooves 26a, 26b are cut out at each of front and rear two places of the outer peripheral surface of each tool transfer pot 26, and the guide pin 62 is engaged with the engaging grooves 26a, 26b. In this way, the tool transfer pots 26, and therefore the tools T, are positioned and supported in the axial and circumferential directions. Next, operation of the tool exchanger 20 of this embodiment is explained. When turning tool process or rotating tool process by the tool T loaded on the tool post body 11 has been completed, the rotationally indexing device 10 turns the tool post body 11 90 degrees about the turning axis A, so that the process-completed tool T0 is indexed and positioned to the tool changing position parallel to the axis of the headstock 7. Meanwhile, during the machining process, the piston rod 36 of the cylinder mechanism 35 moves down so that the gripping member 37 and the presser pin 39 are positioned to the tool takeout position P1. When the tool magazine 21 transfers, indexes and positions a tool transfer pot 26, in which the next-process tool T1 is accommodated therein, to the tool takeout position P1, the gripping member 37 and the presser pin 39 grip the tool transfer pot 26, in which state the piston rod 36 goes up and then turns 90 degrees about the turning axis C. As a result, the next-process tool T1 is turned to a spindle-parallel position parallel to the headstock 7, i.e., to the process-completed tool T0, in which state the piston rod 36 goes down. Then, the guide pins 62 of the pot holding member 60 are engaged with the engaging grooves 26a, 26b of the tool transfer pot 26, in which the next-process tool T1 is accommodated, so that the next-process tool T1 (tool transfer pot) is positioned and supported to the pot holding member 60 at the delivery position P2. Subsequently, the piston rod 57 of the air cylinder 56 retreats, and the transfer arm 49 transfers the pot holding member 60 linearly from the delivery position P2 to the tool changing position P3. In this case, relative motion of the front end of the transfer arm 49 with respect to the block 47b due to the pivoting of the transfer arm 49 is absorbed by the cam follower 55 and the cam groove, and the swing of the air cylinder 56 due to the pivoting of the transfer arm 49 is absorbed by the pivot shaft 58. Then, the changing shaft 31 turns, and the changing arm 32 grips the process-completed tool T0 of the tool post body 11 and the next-process tool T1 in the tool changing position P3. In this state, the changing shaft 31 retreats, and pulls out the process-completed tool T0 from the tool spindle 14 and also pulls out the next-process tool T1 from the tool transfer pot 26. Subsequently, the changing arm 32 turns 180 degrees and advances. Then, the next-process tool T1 is gripped by the tool spindle 14, and the process-completed tool T0 is gripped by the tool transfer pot 26 supported by the pot holding member 60. This process-completed tool T0 is returned to a specified pot position of the tool magazine 21 via the tool transfer mechanism 23 and the tool turning/transferring mechanism 22. As shown above, according to this embodiment, the tool magazine 21 is disposed so that each tool T is directed perpendicular to the axis of the headstock 7, and the next-process tool T1 is taken out from the tool takeout position P1 and turned and transferred to the tool delivery position P2 parallel to the process-completed tool T0 of the tool post body 11 in the spindle-parallel position by the tool turning/transferring mechanism 22, which is comprised of the cylinder mechanism 35 and an unshown turning mechanism. Therefore, in the case where the tool magazine 21 in multi-tool specifications is mounted, the turn of direction of the next-process tool T1 can be achieved with a simple structure. Thus, the tool changer for machine tools of this embodiment is applicable to use in flexible manufacturing systems for production of many items in low volumes as well as automatic continuous operation. In this embodiment, since the tool magazine 21 is so structured that an endless transfer chain 21b is provided in the rear of the tool post 6 on the fixed bed 2 so as to run along the rear face of the machine, a large number of tools T as many as 60 to 180 pieces can be mounted without requiring so much space, thus allowing the use in flexible manufacturing systems for production of many items in low volumes as well as automatic continuous operation. Further, the tool takeout position P1 is set flush with the delivery position P2 and the tool changing position P3, and the next-process tool T1 in the tool takeout position P1 is taken out vertically upward in the unit of the tool transfer pot 26, turned 90 degrees at the upper end position, and thereafter moved down, turned and transferred to the delivery position P2. Therefore, the next-process tool T1 can be transferred from the takeout position P1 to the delivery position P2 smoothly with less operations of up-and-down motion and turning motion. According to this embodiment, the transfer arm 49 is provided pivotable between the tool delivery position P2 and the tool changing position P3, and the piston rod 57 of the air cylinder 56 is coupled to a proximity of the pivot shaft 48 of the transfer arm 49, and moreover the pot holding member 60 is coupled to the front end portion of the transfer arm 49. Therefore, as shown in Fig. 5, a quantity of stroke L2 of the piston rod 57 can be shortened relative to a quantity of linear travel L1 of the pot holding member 60, so that the axial length of the air cylinder 56 can be shortened as compared with the conventional case where the air cylinder having a stroke equal to or more than the travel quantity of the tool pot. Thus, proportionally to this, the installation space for the air cylinder 56 can be reduced, and the cost can be reduced. Further, engaging grooves 26a, 26b extending in the tangential direction are cut out in the tool transfer pots 26 for holding the tool holder 27, and the pot holding member 60 are provided with four guide pins 62 to be engaged with the engaging grooves 26a, 26b. Therefore, the next-process tool T1 can be positioned and supported with a simple structure, and transferred to the tool changing position P3 in the positioned state, thus allowing the positioning accuracy for tool change to be improved. The above embodiment has been described on a case where tools T are placed in the tool magazine 21 so as to be directed perpendicular to the axis of the headstock 7, and the next-process tool T1 is turned and transferred to the delivery position P2 by the tool turning/transferring mechanism 22. However, the tool magazine of the present invention is not limited to this. Fig. 9 shows a tool changer according to another embodiment of the above embodiment, where the same reference numerals as in Fig. 5 designate the same or corresponding component parts. In this tool changer 70, a tool magazine 71 is provided in a longitudinally longer elliptical form, and tools T are so set in the tool magazine 71 as to be parallel to the tool spindle 14 positioned in the tool changing position, i.e., parallel to the process-completed tool TO. Therefore, the tool takeout position P1 in the tool magazine 71 is coincident with the delivery position P2. The piston rod 57 of the air cylinder 56 is coupled to a proximity of the pivot shaft 48 of the transfer arm 49 forming part of the tool transfer mechanism, and a pot holding member 72 is coupled to an upper end portion of the transfer arm 49 via a cam mechanism. A gripping member 73 for gripping the tool holder 27 is provided in the pot holding member 72. Also, a guide plate 74 is fixed to an upper wall of the transfer support base 45, and a U-shaped guide member 75 for guiding the pot holding member 72 in contact with its lower and upper faces is fixed to the guide plate 74. According to this tool changer 70, since the air cylinder 56 is coupled to a proximity of the pivot shaft 48 of the transfer arm 49, the stroke quantity of the piston rod 57 can be made smaller than the travel quantity of the pot holding member 72, so that the same effects as in the foregoing embodiment can be obtained. Also, since the tools T in the tool magazine 71 are so placed as to be directed parallel to the headstock, the need of the aforementioned tool turning/transferring mechanism can be eliminated. Further, since the guide member 75 to contact the lower and upper faces of the pot holding member 72 is provided, the pot holding member 72 can be transferred smoothly.

Claims: A tool changer (20) for machine tools comprising: a tool magazine 21 on which a multiplicity of tools (T) are loaded and which serves for transferring and indexing a next-process tool (T1) to a specified tool takeout position (P1); a tool transfer mechanism (23) for taking out and transferring the next-process tool (T1) positioned in the tool takeout position (P1) to a tool changing position (P3) via a tool delivery position (P2); and a tool changing mechanism (24) for changing a tool (T0) loaded on a tool post (11) with the next-process tool (T1) positioned in the tool changing position (P3), wherein the tool transfer mechanism (23) comprises: a guide plate (46) extending horizontally from the tool delivery position (P2) to the tool changing position (P3); a transfer arm (49) disposed pivotable between the tool delivery position (P2) and the tool changing position (P3); and a cylinder mechanism coupled to the transfer arm (49) and serving for pivotally driving the transfer arm (49), and wherein the guide plate (46) has a linearly extending rail (47a) fixed thereto, the rail has a block (47b) which is engaged with the rail (47a) so as to be slidable via balls interposed therebetween, the block (47b) has a tool holding member connected thereto and serving for holding the next-process tool (T1), the block (47b) being connected to a front end portion of the transfer arm (49) via a cam mechanism 53 which transforms rotational motion of the transfer arm (49) into linear motion along the rail. The tool changer for machine tools as claimed in Claim 1, wherein the cam mechanism (53) is so constructed that a cam plate (54) having a cam groove formed therein is fixed to the block (47b) and a cam follower (55) to engage with the cam groove of the cam plate (54) is attached to the transfer arm (49). The tool changer for machine tools as claimed in Claim 1 or 2, wherein a tool transfer pot (26) for transferring the tool has a tangentially extending engaging groove formed therein, and the tool holding member has a guide pin (62) which engages with the engaging groove to thereby position and support the tool transfer pot (26) in axial and circumferential directions.

Inventors: NAITO MASAHIRO, NAKAMINAMI MASAMITSU, NAITO, MASAHIRO, NAKAMINAMI, MASAMITSU, Naito, Masahiro, co Mori Seiki Co., Ltd., Nakaminami, Masamitsu, c/o Mori Seiki Co., Ltd
Applicants: MORI SEIKI SEISAKUSHO KK, MORI SEIKI CO., LTD.
Application year: 2000
Main classification: B23Q3
IPC codes: B23Q3