Abstract:
A chain-type tool magazine for detachably holding a plurality of pots on a chain and circulating the pots, provided with: U-shaped link members having openings for detachably holding pots, the link members having first rollers protruding on the side of the openings and second rollers on the side opposite from the opening; link members which do not have a roller; a chain assembly in which the plurality of link members are alternately joined by pins in an endless manner; guides for guiding the first rollers and the second rollers so that the chain assembly bends in the forward and reverse directions and circulates in a meandering manner; and driving means for circularly driving the chain assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National Stage patent application of International Patent Application No. PCT/JP2013/080297, filed Nov. 8, 2013, which is hereby incorporated by reference in the present disclosure in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a chain-type tool magazine for storing a plurality of tools adapted to be used in a machining center etc. 
       BACKGROUND OF THE INVENTION 
       [0003]    A tool magazine, disposed adjacent to a machine tool and adapted to store a plurality of tools and select one from the stored tools in accordance with a machining program so as to advantageously supply it to the machine tool. For example, PLTs 1 and 2 describes chain-type tool magazines. 
         [0004]    PLT 1 describes a separate chain-type tool magazine which allows the tools to be removed, along with pots holding the tools, from the chain. This chain-type tool magazine allows the chain to run along a traveling route having concave and convex parts so as to increase the volume efficiency of the tool magazine. PLT 2 describes a chain-type tool magazine which comprises an endless chain with two rhombus plates which are disposed apart from each other in the axial direction of a pot and connected by a pin. 
       PATENT LITERATURE 
       [0005]    PLT 1: Japanese Patent No. 4120863 B 
         [0006]    PLT 2: Japanese Examined Patent Publication No. H06-007871 B 
       SUMMARY OF THE INVENTION 
       [0007]    According to the chain of PLT 1, the radius of curvature of the circulating track at a curved part curved into a recessed shape must be increased in order to prevent the plates from interfering with each other due to the generally recessed shape of the plates, and therefore in the tool magazine of PLT 1, the volumetric efficiency or space saving effect is insufficient. 
         [0008]    The chain of PLT 2 can run along a serpentine track within a small space because the movable range at the connections is relatively wide. However, pots cannot be removed from the chain, and therefore, the tools must be moved in the axial direction in order to be attached to or removed from the chain, resulting in increase in the complexity of a tool transferring device (shifter), further resulting in increase in the manufacturing cost and increase in the time for preparing tools. 
         [0009]    Further, according to the tool magazines of PLTs 1 and 2, when heavy tools or long tools are attached to the chain, the chain is warped whereby the tools are inclined so that their fronts are lowered, resulting in generation of vibrations of the chain or falling of the tools due to the vibrations of the chain. Thus, the driving speed of the chain must be reduced. 
         [0010]    Further, in the tool magazines described in PLTs 1 and 2, sprockets are used for driving the chains. The relative positions of engagement between the chain and the sprockets are changed during the rotation of the sprockets. Therefore, there is a problem accompanied with the configuration that the running speeds of the chains are not constant, which results in generation of vibrations. Furthermore, in the tool magazines of PLTs 1 and 2, sprockets having relatively small diameters are used for the curved portions of the circulating tracks, and therefore the contacting areas between the chains and the sprockets are relatively small, increasing the contacting pressures. 
         [0011]    The invention is directed to solve the above-described problems of the prior art, and the objective of the invention is to provide a chain-type tool magazine which allows the tool preparing operation, i.e., removing tools from the tool magazine and loading tools into the tool magazine, to be carried out in a short time, and also to provide a chain-type tool magazine which has a high density of tools stored, and can store more tools in the tool magazine. 
         [0012]    In order to solve the above-described problem, the invention provides a chain-type tool magazine including a circulating chain, for removably holding a plurality of pots, to which the tools are attached, or a plurality of tools, the tool magazine comprises, link members each has an opening for removably holding the pot or the tool, first rollers provided at the opening side and second rollers provided opposite side to the opening, an endless chain formed by coupling a plurality of the link members, a guide for guiding the first rollers and second rollers to allow the chain to circulate along a serpentine track having turns to one side and to the opposite side, and drive means for driving the chain to circulate. 
         [0013]    According to the invention, the configuration for supporting the chain relative to the guide by the first rollers disposed at the opening of the link member, and the second rollers disposed at the opposite side to the opening, allows the chain to bend in both the left and right directions relative to the running direction, enabling the tool magazine to increase the tool storing density. Further, the openings defined in the chain allows the tools to be removed from the chain without moving the tools in the axial direction, whereby the time for preparing the tools can be reduced. Furthermore, the configuration for supporting the chain relative to the guide by the first and second rollers prevents the chain from being warped whereby the tools are inclined so that their fronts are lowered, by heavy tools or long tools attached to the chain, enabling the chain to run at high speed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a plan view of a chain-type tool magazine according to a first embodiment of the invention. 
           [0015]      FIG. 2  is a front view of the chain-type tool magazine of  FIG. 1  with a cover of the chain-type tool magazine being eliminated. 
           [0016]      FIG. 3  is a front view of the chain-type tool magazine of  FIG. 2  with a chain assembly being eliminated in order to show outer and inner guide rails clearly. 
           [0017]      FIG. 4  is a perspective view of the chain-type tool magazine of  FIG. 2 . 
           [0018]      FIG. 5  is a perspective view showing portions of the chain assembly and the inner guide rail. 
           [0019]      FIG. 6  is a partial perspective view of the chain assembly similar to  FIG. 5  from which the inner guide rail is eliminated. 
           [0020]      FIG. 7  is a front view showing a portion of the chain assembly. 
           [0021]      FIG. 8  is a partial side view of the chain assembly viewing in the direction of arrows VIII-VIII in  FIG. 7 . 
           [0022]      FIG. 9  is a section along line IX-IX in  FIG. 8 . 
           [0023]      FIG. 10  is a plan view of a link plate of a first link member. 
           [0024]      FIG. 11  is a plan view of a link plate of a second link member. 
           [0025]      FIG. 12  is a partially sectional plan view of a shifter when it is in an unclamping state. 
           [0026]      FIG. 13  is a front view of the shifter of  FIG. 12 . 
           [0027]      FIG. 14  is a partially sectional plan view of a shifter when it is in a clamping state. 
           [0028]      FIG. 15  is a front view of the shifter of  FIG. 14 . 
           [0029]      FIG. 16  is a partial front view of a variation of the chain assembly according to the first embodiment. 
           [0030]      FIG. 17  is a front view of a chain-type tool magazine according to a second embodiment of the invention. 
           [0031]      FIG. 18  is front view showing a portion of the chain assembly of  FIG. 17 . 
           [0032]      FIG. 19  is a partial side view of the chain assembly viewing in the direction of arrows IXX-IXX in  FIG. 18 . 
           [0033]      FIG. 20  is a section along line XX-XX in  FIG. 19 . 
           [0034]      FIG. 21  is a partially sectional plan view of the shifter when it is in an unclamping state, showing along with the chain assembly of  FIG. 17 . 
           [0035]      FIG. 22  is a front view of the shifter of  FIG. 21 . 
           [0036]      FIG. 23  is partially sectional plan view of the shifter when it is a clamping state, showing along with the chain assembly of  FIG. 17 . 
           [0037]      FIG. 24  is a front view of the shifter of  FIG. 23 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    With reference to the drawings, a first embodiment of the invention will be described below. 
         [0039]    In  FIG. 1 , a tool magazine  100  according to the first embodiment of the invention is disposed at one side of a machine tool  10 . The machine tool  10  forms a horizontal machining center, comprising a bed  12  providing a base, table  14  mounted to a top face of the bed  12  at the front part thereof for moving horizontally in Z-axis direction (up-and-down direction in  FIG. 1 ), a column  16  mounted to the top face of the bed  12  at the rear side thereof opposite to the table  14  for moving horizontally in X-axis direction (left-and-right direction in  FIG. 1 ), a headstock  18  mounted to a front face of the column  15  for moving vertically in Y-axis direction (perpendicular to the plane of  FIG. 1 ) and a spindle head  20  mounted to the headstock  18  for rotationally supporting a spindle  22  about a horizontal axis O. A tool changer  24  is disposed between the machine tool and the tool magazine  100 . The tool changer  24  has a changing arm  24  rotatable about a rotational axis O tc  extending in the Z-axis direction. 
         [0040]    The tool magazine  100  comprises a base part  104  secured to a floor, a back support part  102  vertically upwardly extending from the base part  104 , outer and inner guide rails  110  and  120  mounted to the back support part  102  in the form of a plate, a chain assembly extending between the outer guide rail  110  and the inner guide rail  120 , a cam shaft (gear cam)  160  in the form of a screw as a drive unit for driving the chain assembly along the outer guide rail  110  and the inner guide rail  120 , a drive motor  162  for driving the cam shaft  160 , a shifter  170  for transferring a tool between the tool changer and the chain assembly  130  and a cover  108  for covering the above described elements. 
         [0041]    The outer guide rail  110  and the inner guide rail  120  are disposed apart from each other by a predetermined distance so as to extend parallel to each other, whereby a circulating track in the form of an inverted U shape is defined for the chain assembly  130 . In particular, as shown in  FIG. 2 , the circulating track  180  for the chain assembly  130  has a large arc part  182  in the form of a semicircular provided at the highest position, a first linear part  182   b  extending linearly downwardly from one end of the large arc part  182   a , a first small arc part  182   c  in the form of a semicircular connected to the lower end of the first linear part  182   b  and provided at the lowest position, a second linear part  182   d  extending linearly upwardly from the first small arc part  182   c , a second small arc part  182   e  in the form of a semicircular connected to the upper end of the second linear part  182   d  and provided inside the large arc part  182 , a third linear part  182   f  extending linearly downwardly from the second small arc part  182   e , a third small arc part  182   g  in the form of a semicircular connected to the lower end of the third linear part  182   f  and provided at substantially the same level as the first small arc part  182   c  and a fourth linear part  182   h  extending linearly upwardly from the third small arc  182   g  to the large arc part  182   a . In this embodiment, the cam shaft engages the chain assembly  130  at the fourth linear part  182   h.    
         [0042]    The outer guide rail  110  comprises first and second guide rails  112  and  114  disposed apart from each other by a distance in the direction perpendicular to the back support part  102 . The first guide rail  112  of the outer guide rail  110  is mounted via base pieces  116  at a predetermined distance relative to the back support part  102 . The second guide rail  114  is mounted via spacer pins (not shown) at a predetermined distance relative to the first guide rail  112 . 
         [0043]    The inner guide rail  120  comprises first and second guide rails  122  and  124  disposed apart from each other by a distance in the direction perpendicular to the back support part  102 . Each of the first and second guide rails is formed by a plurality of rail segments. The first guide rail  122  of the inner guide rail  120  is mounted via base pieces  126  at a predetermined distance relative to the back support part  102 . The second guide rail  124  is mounted via spacer pins (not shown) at a predetermined distance relative to the first guide rail  122 . 
         [0044]    The chain assembly  130  comprises an endless chain formed of first link members  132  and second link members  148  connected to each other by connecting pins  154 . The first line member  132  comprises parallel two link plates  134 , which have the same shape, and a block disposed between the two link plates  134 . The link plates  134  are secured to each other so as to be apart from each other by the block  136  and pins  140 . The link plates  134  are U-shaped plate members each having a base portion  134   a  secured to the block  136  and a pair of arm portions  134   b  extending from the base portion  134   a . An opening  134  adapted to receive a pot TP is formed between the pair of arm portions  134   b . The first link member  132  has four distal rollers  142 , providing first rollers, mounted to the arm portions  134   b  at the ends thereof and four proximal rollers  138 , providing second rollers, mounted between the corners of the base portions  134   a  and the block  136 . Further, two cam followers  144 , adapted to engage the cam shaft  150 , are mounted to the back face of the block  136 . The two cam followers  144  are disposed apart from each other in the direction of the movement of the first link member  134  by a distance the same as the pitch of the cam shaft  160  in the form of a screw. 
         [0045]    The second link member  148  comprises two parallel link plates  150  having the same shape. The two link plates  150  are secured to each other so as to be apart from each other by pins  152 . The link plates  134  are U-shaped plate members each having a base portion  150   a  and a pair of arm portions  150   b  extending from the base portion  150   a . An opening  150   c  adapted to receive the pot TP is formed between the pair of arm portions  150   b . The arm portions  150   b  of the link plate  150  of the second rink member  148  are shorter than the arm portions  134   b  of the link plate  134  of the first link member  132 . The first and second link members  132  and  148  has leaf springs  156  adapted to engage pot TP whereby the pot TP is held in the openings  134   c  and  150   c  of the first and second link members  132  and  148  ( FIG. 9 ). In particular, as understood from  FIG. 6 , the first and second link members  132  and  148  are connected to each other by connecting pins  154  at substantially the center in the crosswise direction of the circulating track  180 . This allows the chain assembly  130  to be bend about the respective connecting ping  154  in the opposing directions. 
         [0046]    When the chain assembly  130  is disposed on the circulating track  180  between the outer guide rail  110  and the inner guide rail  120 , the cam followers  144  of the first link members  132  are positioned between the first and second guide rails  122  and  124  of the inner guide rail  120  to contact therewith (refer to  FIG. 5 ). The four proximal rollers  138  of the first link member  132  contact the sides of the first and second guide rails  122  and  124  of the inner guide rail  120  while the distal rollers  142  contact the sides of the first and second guide rails  112  and  114  of the outer guide rail  110 . Furthermore, the first and second rink members  132  and  148  are connected to each other at a pitch so that the cam followers  144  of both the first link member  132  at the either sides of one of the second link members  148  can simultaneously engage the cam shaft  160 . 
         [0047]    Furthermore, pots TP are disposed in the openings  134   c  and  150   c  of the first and second link members  132  and  148  so that the tools (not shown) extend to the direction away from the back support part  102 . The pots TP are held within the openings  134   c  and  150   c  through the engagements with the leaf springs  156 . 
         [0048]    The shifter  170  clamps a tool, along with the a pot TP fitted to the tool, held by the first rink member  132  or the second link member  148  positioned at a tool transferring position  184  defined on the circulating track  180  for the chain assembly  130  between the outer and inner guide rails  110  and  120 . The shifter transfers the tool horizontally to a shifting position  186  where tools can be interchanged relative to the tool changer  24 . Further, at the shifting position  186 , the shifter receives from the tool changer  24  a tool held at an end of the changing arm  26  of the tool changer  24  so as to transfer it to empty one of the first or second link member  132  or  148  waiting at the tool transferring position  184 . 
         [0049]    With reference to  FIGS. 12-15 , the shifter  170  comprises a base plate  172  secured to the back support part  102 , a shift cylinder  174  mounted to the base plate  172 , and a clamper  176  connected to a piston of the shift cylinder  174 . The clamper  176  comprises a clamp cylinder  176   a  connected to the piston of the shift cylinder  174 , a clamp piston  176   b  mounted to the clamp cylinder  176   a  for sliding in the longitudinal direction of the shift cylinder  174 , a fixed arm  176   c  fixed to the clamp cylinder  176   a  engageable with a side of a pot TP, a movable arm  176   d , pined to the clamp piston  176   b , for engaging with and disengaging from the opposite side of the pot TP. The movable arm  176   d  is rotatably restricted by the clamp cylinder  176   a , and rotatably connected to the clamp cylinder  176   a  so that the end of the movable arm engages the side of the pot TP opposite to the fixed arm ( FIGS. 14 and 15 ), and disengages from the side ( FIGS. 12 and 13 ) when the clamp piston  176   b  slides relative to the clamp cylinder  176   a . The end of the movable arm  176   d  is provided with fingers in the form of bifurcated wedges which presses and opens the leaf spring  156  when engaging the side of the pot TP, so that the pot TP is held and transferred. 
         [0050]    In the above described first embodiment, the chain assembly  130  has first link members  132  and the second link members  148 . The invention is not limited to this configuration, the chain assembly  130  may by formed by connecting the same link members. With reference to  FIG. 16 , a chain assembly  190  according to a variation of the first embodiment is composed of identical link members  192  rotatably connected to each other by connecting pins  198 . Each of the link members  192  comprises distal rollers  194  providing first rollers attached to the ends of arm portions  192   a , and proximal rollers  196  providing second rollers mounted to the base portion. 
         [0051]    In the invention thus formed, the chain assembly  130  bends in a direction at the large arc part  182   a  and the first and third small arc parts  182   c  and  182   g  of the circulating track  180 , while it bends in the opposite direction at the second arc part  182   e . The connecting pins  154 , connecting the first and second link members  132  and  148 , are positioned near the path traced by the centers of the conveyed tools, and therefore, the chain assembly can bend largely in both directions without increasing the bending radius. Accordingly, the invention provides a tool magazine, in which the chain assembly  130  can run along the serpentine track having as small curves as possible so as to store the tools at high density. The chain assembly having the openings  134   c  and  150   c  allows preparation of tools in a short time. 
         [0052]    The configuration of the first and second link members  132  and  148  having the openings  134   c  and  150   c , in which the first and second rollers (the distal rollers and the proximal rollers)  142  and  138  guided by the outer guide rail  110  and the inner guide rail  120  or the configuration of the first link members  132  provided with the pair of the cam followers  144  which simultaneously contact the first and second guide rails  122  and  124  allows the chain assembly  130  to run at a high speed without the chain assembly warped, without the tools inclined so that their fronts are lowered or without the tools fallen. Further, the configuration for driving the chain assembly  130  via the engagement between the cam followers  144  and the cam shaft (gear cam)  160  removes the minute variations in the running speed, which is a disadvantage involved in drives composed of sprockets and a chain, whereby the chain assembly  130  can run without vibrations. 
         [0053]    While the part, corresponding to the large arc part  182   a  of the circulating track  180 , is conventionally commonly formed of a horizontally extending linear part and guides, in the form of a relatively small arc, for changing the direction at a right angle at the ends of the linear part, in the invention it is formed into a large arc shape. In the conventional configuration, the stress is concentrated to the small arc guides due to the weight of the chain assembly  130  when the chain assembly  130  passes the small arc guides. Therefore, the small arc guides and the proximal rollers  138  must be made of a high rigidity material or a hardened material, increasing the cost of the chain-type tool magazine. Therefore, in the invention, the part is replaced with the large arc part  182   a  which removes the stress concentration, which is occurs in the conventional configuration, and eliminates the necessity of using a high rigidity or hardened material, contributing to provide a low-cost configuration. In this application, the large arc shape refers to the shape of the portion  182   a  connecting the maximum width of the chain assembly  130  with a smooth curvature, which does not includes a linear track portion. 
         [0054]    The tool change between the spindle  22  and the tool magazine  100  is carried out by rotationally and reciprocally moving the changing arm  26 , in the form of a well-known double arm shape, around the axis O tc  and in the Z-axis direction after a pot TP, to which the tool to be changed is fitted, is positioned at the shift position  186  by the shifter  170 , and the spindle  22  is positioned at a tool changing position  188 . 
         [0055]    With reference to  FIGS. 17-25 , a second embodiment of the present invention will be described below. 
         [0056]    In the second embodiment, the elements commonly sharing with the first embodiment are indicated by the same reference numbers. A tool magazine  100 ′ of the second embodiment has a basic structure, the same as the first embodiment, for driving an endless chain assembly  130 ′, formed of the first and second link members  132  and  148  connected by connecting pins  154 , along the outer and inner guide rails  110  and  120 , by the cam shaft  160 , and transferring a tool to be changed to the shift position  186  by a shifter  170  provided at the tool transferring position  184 . The second embodiment differs from the first embodiment in respect that the tools are attached directly to the chain assembly  130 ′ without using the pots TP. It should be noted that in this application, tool T includes, as well as a shank and cutter body connected to the shank, a tool holder which is fitted to the shank. 
         [0057]    As shown in  FIGS. 18-20 , a gripper for removably holding a tool T is provided. The gripper has a pair of jaws  200  mounted, by a pivot pin  202 , to one of the two parallel link plates  134  and  150  disposed at the front side. The pair of jaws  200  are biased toward each other by a spring  204  whereby the gripper holds a flange portion of the tool T. The configurations of the first and second link members  132  and  148 , the proximal rollers  138 , the distal rollers  142 , the cam followers  144  and the connecting pins  154  are the same as the first embodiment, and therefore their explanation will be omitted. 
         [0058]    With reference to  FIGS. 21-25 , the shifter  170 ′ will be described below. A tool transferring pot  210  is advanced by a cylinder  214  toward a tool T, from its shank, positioned at the tool transferring position  184 , to grasp the tool T. The cylinder  214  is fixed to the piston of the shift cylinder  174  via a bracket  212  so that when the piston of the shift cylinder  174  is extended, the tool T is disengaged from the jaws  200  of the gripper against the biasing force of the spring  204  to move to the shift position  186 . After tools are changed by the tool changer  24 , a tool T, which has been changed, will be attached to the chain assembly  130 ′ by the inverted process. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           10  Machine Tool 
           22  Spindle 
           26  Changing Arm 
           100 ,  100 ′ Tool Magazine 
           110  Outer Guide Rail 
           120  Inner Guide Rail 
           130 ,  130 ′ Chain Assembly 
           132  First Link Member 
           134  Link Plate 
           136  Block 
           138  Proximal Roller 
           142  Distal Roller 
           144  Cam Follower 
           148  Second Link Member 
           150  Link Plate 
           154  Connecting Pin 
           160  Cam Shaft 
           170 ,  170 ′ Shifter 
           180  Circulating Track 
           184  Tool Transferring Position