Abstract:
A ball-spline with rotary mechanism is provided which is as small as possible in size, able to perform high-precision works on a small scale and also weighs less than ever, helping the downsizing of the component-placement systems. The ball-spline has a spline shaft, a slider movable along the spline shaft through balls, and bearings installed on the opposite ends of the slider for rotation relative to a machine bed. The holder has a pair of projections which extend through slots in the spacer parts and slots in the end-cap major body to fit into slots in a carriage. Fastening screws fit into threaded holes in the projections to fasten the holder to the opposite ends of the slider.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a ball-spline with rotary mechanism, which is better for a component-placement head to be used in an upright or vertical posture in a diversity of manufacturing machines including, for example, semiconductor fabricating equipment, assembling machines and so on. 
     BACKGROUND OF THE INVENTION 
     Recently advanced electronics are increasingly required to be more miniaturized or downsized with high performance. Correspondingly, the ball-splines with rotary mechanism used as the component-placement heads in diverse industrial fields including semiconductor fabricating equipment, assembling machines and so are also challenged to help the downsizing of the electronics with high performance. 
     In Japanese Laid-Open Patent Application No. 2004-128 485, there is described an example of the ball-spline with rotary mechanism, which is used for the component-placement head. With the prior ball-spline with rotary mechanism, a pair of first and second sliders is installed on a spline shaft, spaced away at a preselected interval from each other. The spline shaft is allowed to travel up and down relatively to the sliders by virtue of rolling elements or balls. With the prior ball-spline with rotary mechanism, moreover, there are provided bearing mountings one of which is installed above the first slider and another mounting is below the second slider. Cylindrical members are provided one of which fits over the first slider while another embraces around the second slider. An intermediate cylindrical member is provided which extends across the first and second sliders to fit over both the sliders and connect integrally the sliders with each other. Thus, the cylindrical members are integrally supported by means of the bearings for rotation around the lengthwise center of the spline shaft with respect to a head frame. 
     With the ball-spline with rotary mechanism built in the component-placement head, the cylindrical members have the beating mountings near the sliders, respectively, which fit snugly into the cylindrical members. The bearings that have fit over bearing mountings are slightly larger in outside diameter than the cylindrical members and therefore the bearings around outer circular surfaces of their outer rings closely fit into the head frame to bear the ball-spline for rotation with respect to the head frame. Thus, the prior ball-spline with rotary mechanism constructed as stated earlier couldn&#39;t get out of becoming bigger in the outermost diameter by as twice as the radial thickness of the cylinder member that has fit over the relevant slider. This means the prior art is inevitably disadvantageous to downsizing the ball-spline with rotary mechanism. Moreover, the cylindrical members have to be worked or finely finished over the inside circular surface thereof so as to closely fit over the outside circular surface of the relevant slider. This also means the prior construction as stated earlier involves additional manufacturing steps for ensuring high precision in assemblage. 
     Referring to  FIG. 8 , there is shown a conventional ball-spline which is mainly composed of a spline shaft  51  of right circular cylinder having raceway grooves  56  lying diametrically opposed to each other on a circular surface of the cylinder to extend lengthwise of the cylinder, and a slider  52  that fits over or conforms to the spline shaft  51  so as to travel up and down along the spline shaft  51  in a sliding manner by virtue of rolling elements or ball  57 . The slider  52  is composed of a carriage  53  of a cylindrical shell that fits over the spline shaft  51 , end caps  54  secured on lengthwise opposite ends of the carriage  53 , one to each end, end seals  55  arranged on outward ends of the end caps  54  to close an annular clearance between the spline shaft and the slider  52 , and a plurality of rolling elements allowed to roll in a recirculating manner through looped circuits. The carriage  53  has raceway grooves  61  cut in an inside circular surface thereof in opposition to the raceway grooves  56  on the spline shaft  51  to define load-carrying raceways  62  between them, and return passages  58  extending in parallel with the load-carrying raceways  62 . The end caps have turnaround passages to connect the load-carrying raceways  62  to the return passages  58  to provide the looped circuits made up of the load-carrying raceways  62 , return passages  58  and a pair of the turnaround passages. The end caps  54  and end seals  55  are secured on the carriage  53  by means of fastening screws  59 . The spline shaft  51  comes into mating with the slider  52  through the rolling elements  57  to provide nearly frictionless linear sliding motion relatively to each other while allowing transmitting torque between them simultaneously. The slider  52  on a circular outside thereof has a key slot  60  into which a key fits to keep the slider  52  against rotation relative to a machine housing the slider  52  therein. 
     As the advanced electronics become more downsized even with high performance, the ball-spline with rotary mechanism for the component-placement heads in diverse industrial fields including semiconductor fabricating equipment, assembling machines and so on are needed to be downsized with high performance to help the miniaturization or downsizing of the component-placement systems that the ball-spline with rotary mechanism is built in. 
     SUMMARY OF THE INVENTION 
     The present invention has for its primary object to overcome the major challenge as stated earlier, and to provide a ball-spline with rotary mechanism that is as small as possible in size and also weighs less than ever, helping the downsizing of the component-placement systems that the ball-spline with rotary mechanism is built in. 
     The present invention is concerned with a ball-spline with rotary mechanism, comprising; an elongated spline shaft circular in transverse section having raceway grooves extending lengthwise of the spline shaft on a circular surface of the shaft at locations angularly opposite to each other, a slider fitting over or conforming to the spline shaft to move up and down along the spline shaft in a sliding manner by virtue of rolling elements of balls, holders lying on lengthwise opposite ends of the slider, and rolling-contact bearings installed to keep the holders for rotation relative to a machine bed; 
     wherein the slider is composed of a carriage of a cylindrical shell having raceway grooves on an inside circular surface thereof in opposition to the raceway grooves on the spline shaft to define load-carrying races between the raceway grooves on the spline shaft and the raceway grooves on the carriage and further having return passages extending in parallel with the load-carrying races, end caps attached to lengthwise opposite ends of the carriage, the end caps having turnaround passages to connect the load-carrying races with the return passages, and the balls recirculating through a looped circuit made up of the load-carrying races, return passages and the turnaround passages; 
     wherein the carriage has a pair of first slots extending lengthwise of the carriage on the inside circular surface at circularly opposite locations in symmetry with each other and the end caps have paired second slots extending lengthwise of the end caps on inside circular surfaces thereof to communicate with the first slots; and 
     wherein the holders each have a flanged portion adjacent to the end of the slider, a pair of projections extending integrally from an end surface of the flanged portion to fit into the first slots in the carriage across the second slots in one of the end caps, and a bearing mounting of a cylinder formed integral with the flanged portion to extend from another end surface opposite to the end surface of the flanged portion to fit snugly into an inner ring of one of the rolling-contact bearings. 
     In the present invention, a ball-spline with rotary mechanism is provided in which the projections on one of the holders each include a first portion to fit into the first slot and a second portion to fit into the second slot and a gap lying at a boundary between the first portion and the second portion to provide a stepwise edge which is envisaged coming into abutment against one of the lengthwise opposite ends of the carriage, locating in place the holder with respect to one of the lengthwise opposite ends of the slider to fasten the holder to the slider. 
     In the present invention, a ball-spline with rotary mechanism is provided in which a pair of the sliders fits over the spline shaft in lengthwise opposition to each other in a relation spaced at a preselected interval from each other, a cylindrical collar interposed between the sliders is fixed to inward ends of the sliders, the holders having the rolling-contact bearings fit over outward ends of the sliders, the cylindrical collar on lengthwise opposite ends thereof being formed with projections identical in construction with the projections of the holders, and the projections, after inserted into the first slots in the carriage, are clamped to the sliders. 
     In the present invention, a ball-spline with rotary mechanism is provided in which at least one of the holders has a cylindrical portion integral with the bearing mounting and having mounted thereon rotary driving part for sliding movement relative to the spline shaft. 
     In the present invention, a ball-spline with rotary mechanism is provided in which the projections of the holders have threaded holes at areas lying in opposition to threaded holes in the first slots inside the carriage, so that fastening screws, after having stretched through the threaded holes in the carriage, fit into the threaded holes in the projections to fasten the holders to the carriage. 
     In the present invention, a ball-spline with rotary mechanism is provided in which the first slots are formed with the help of unused areas there is none of the raceway grooves, the return passages and threaded holes used to fasten the carriage to the end caps. 
     In the present invention, a ball-spline with rotary mechanism is provided in which the end caps are each constituted with a spacer part attached to one of the end surfaces of the carriage and provided therein with inside curved halves of the turnaround passages, and an end-cap major body secured on an outward surface of the spacer part in adjacent to the flanged portion of the holder and provided therein with outside curved halves of the turnaround passages. 
     ADVANTAGEOUS EFFECTS OF THE INVENTION 
     In the ball-spline with rotary mechanism constructed as stated earlier according to the present invention, since the slider has the slots on the inside circular surface thereof and the holders to install the bearings at the opposite ends of the slider have the projections to fit into the slots, there is no need to mount any other additional component around the slider. Thus, the ball-spline with rotary mechanism, as being compact or slim in the overall outside dimension, can be downsized as small as possible and is adapted to perform high-precision works on a small scale. As only the complementary fit between the slots and the projections is sufficient to join the sliders and holders together, there is no need of high-precision works for complementary fit over wide mating surfaces and, therefore, the holders are easy for machining works. Moreover, the complementary fit between the slots inside the slider and the projections out of the holder is effective in weight reduction of the overall construction. With the alternative version of the ball-spline with rotary mechanism in which the collar is interposed between the sliders, as the collar may be made with a member less in the outside diameter and, therefore, easy for machining works. The alternative version is made as small as possible in size, able to perform high-precision works on a small scale and also weighs less than ever, helping the downsizing of the component-placement systems and, therefore, more adapted to the high-speed machines. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view in front elevation showing a preferred embodiment of a ball-spline with rotary mechanism constructed according to the present invention: 
         FIG. 2  is a view in end elevation of the ball-spline with rotary mechanism of  FIG. 1 : 
         FIG. 3  is an exploded view in perspective to illustrate the ball-spline with rotary mechanism of  FIG. 1 : 
         FIG. 4  is a view in longitudinal section taken on the plane of the line IV-IV of  FIG. 2 : 
         FIG. 5  is a view in front elevation showing a second version of the ball-spline with rotary mechanism according to the present invention: 
         FIG. 6  is a view in end elevation showing a collar in  FIG. 5 : 
         FIG. 7  is a view in longitudinal section of the collar of  FIG. 5 , taken on the plane of the line VII-VII of  FIG. 6 : and 
         FIG. 8  is a view in perspective, partially broken away, showing a conventional ball-spline. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the ball-spline with rotary mechanism according to the present invention will be explained hereinafter in detail with reference to the accompanying drawings. The ball-spline with rotary mechanism of the present invention is suited for the component-placement head which is envisaged working in an upright or vertical posture in a diversity of manufacturing machines including semiconductor fabricating equipment, assembling machines and so on. More especially, the ball-spline with rotary mechanism of the present invention features an application of rolling-contact bearings to the conventional ball-spline working as the linear motion guide unit, and further an assembling construction between tubular holders  7 ,  8  and sliders  2 ,  2 A,  2 B to make it possible to install the rolling-contact bearings  9   10  at lengthwise opposite ends of the slider  2 . 
     Referring first to  FIGS. 1 to 4 , there is shown a preferred embodiment of the ball-spline with rotary mechanism according to the present invention. With the ball-spline with rotary mechanism, the slider  2  is carried on a head frame or machine frame  36  of a component-placement head in, for example, a pick-and-place machine for rotation through the rolling-contact bearings  9 ,  10  and a spline shaft  1  fits into the slider  2  so as to travel up and down through a plurality of rolling elements or balls  45  in a sliding manner with respect to the carried slider  2 . Thus, the spline shaft  1  is allowed to rotate while free to travel up and down simultaneously relative to the head frame or machine frame  36 . After the ball-spline with rotary mechanism has been actuated, a nozzle head, not shown, at the tip of the spline shaft  1  pneumatically picks up a component or part from a feeder or tray, rotates the component to the correct orientation and then moves down towards a preselected location on, for example a printed circuit board with high precision. 
     The ball-spline with rotary mechanism is composed of the spline shaft  1  circular in transverse section having lengthwise raceway grooves or first raceway grooves  12  lying on a circular surface of the shaft  1  at locations diametrically opposite to each other, the slider  2  allowed to move up and down along the shaft  1  in a sliding manner by virtue of the rolling elements or balls  45 , and the rolling-contact bearings  9 ,  10  installed with intervention of the tubular holders  7 ,  8  on lengthwise opposite ends of the slider  2 . The slider  2  is provided on an inside circular surface thereof with lengthwise slots  21 ,  22  and  23  while the tubular holders  7 ,  8  to be intervened between the ends of the slider  2  and the rolling-contact bearings  9 ,  10  have projections  20  which are formed to snugly fit into the slots  21 ,  22  and  23 . Mating engagement between the projections  20  and the slots  21 ,  22  and  23  complement each other contributes to the provision of the ball-spline with rotary mechanism compact in construction as a whole and less in weight. 
     The rotary mechanism combined with the ball-spline is constituted with the rolling-contact bearings  9 ,  10  installed at the lengthwise opposite ends of the slider  2  in the ball-spline in which the slider  2  fits over the spline shaft  1  to travel up and down the shaft  1  in a sliding manner. The ball-spline with rotary mechanism of the present invention is shrunk in overall dimension, for instance, an outside diameter of the spline shaft  1 : 5 mm, an outside diameter of the slider  2 : 9.9 mm, and the rolling-contact bearings  9 ,  10  are miniature ball bearings having the dimensions of an inside diameter: 7 mm, an outside diameter: 11 mm, and an axial length: 3 mm. 
     The slider  2  as shown in  FIGS. 1 to 3  is composed of a carriage  3  of a cylindrical shell that fits over the spline shaft  1  for sliding movement relative to the spline shaft  1 , the carriage  3  having lengthwise raceway grooves or second raceway grooves  24  in opposition to the first raceway grooves  12  cut on the spline shaft  1 , and end caps  4  attached to lengthwise opposite ends of the carriage  3 , one to each end, the end caps  4  having spacer parts  6  lying on end surfaces  29  of the carriage  3  and end-cap major bodies  5  combined in close contact and in axial alignment with the spacer parts  6 . On the lengthwise opposite ends of the slider  2 , there are provided the rolling-contact bearings  9 ,  10  with intervention of the tubular holders  7 ,  8  in such a relation that the bearing  9 ,  10  are raised a little in a radial direction above the outside diameter of the slider  2 . The rolling-contact bearings  9 ,  10  are composed of inner rings  15  mounted on shoulders  33  of the tubular holders  7 ,  8 , outer rings  14  surrounding the inner rings  15  for rotation relative to each other and kept in place inside the machine frame, and the rolling elements  16  interposed between the outer ring  15  and the inner ring  14 . With the embodiment discussed here, the outer rings  14  of the rolling-contact bearings  9 ,  10  each have a radial dimension raised slightly above the outside diameter of the slider  2 , and the tubular holders  7 ,  8  are secured to the slider  2 . The tubular holders  7 ,  8  have inside circular surfaces which are isolated away from the spline shaft  1  so as not to touch the spline shaft  1  as in the inside circular surface of the slider  2 . The tubular holders  7 ,  8  each have a flanged portion  13  identical in an outside diameter with the slider  2 , a bearing mounting  31  adjacent to the flanged portion  13 , and a collar extending towards the slider  2  from an end opposite to the flanged portion  13 . 
     The ball-spline with rotary mechanism constructed according to the first embodiment as stated earlier is envisaged having been employed in the pick-and-placement head. The tubular holder  7  laid on one side, left in  FIG. 1 , of the slider  2  has a cylindrical portion  19  which is to have a gear wheel thereon and terminates to external threads  32 . Thus, the cylindrical portion  19  has mounted thereon driving parts to transmit the rotary power of a motor, not shown, to the spline shaft  1  through the tubular holder  7 . Another tubular holder  8  laid on the other side of the slider  2  has only an axial length sufficient to fit just into the rolling-contact bearing  10 . With the embodiment constructed as stated earlier, the tubular holders  7 ,  8  installed on opposite sides of the slider  2  have the respective rolling-contact bearings  9 ,  10 . The slider  2  employed here is of long type having more load-carrying capacity than in the standard product. The slider  2 , as having the carriage  3  longer than in the standard product, makes the raceway grooves  24  in the slider  2  longer than ever and correspondingly making it possible to increase the number of the rolling elements  45  so as to carry heavier load. Thus, it is to be understood that the ball-spline with rotary mechanism of the first embodiment is made more compact in lengthwise direction, as compared with a ball-spline with rotary mechanism having a pair of sliders  2 A,  2 B as will be stated later. 
     Moreover, the tubular holders  7 ,  8  as shown in an exploded perspective view of  FIG. 3  each have a pair of the projections  20  extending integrally from an end surface of the flanged portion  13  into the interior of the slider  2 . The projections  20  each have a length which falls short of a half the overall axial length of the carriage  3  so as not to come into hitting against the projections  20  of the counter tubular holder  8 . The paired projections  20  on one of the tubular holders  7 ,  8  have inside circular surfaces lying in diametrically opposite relation with each other and extending in coplanar with the inside circular surface of the flanged portion  13 . The projections  20  each have a rectangular configuration in transverse section and have an outside circular surface which includes a first distal outside circular surface put deep into the carriage  3  and a second proximal outside circular surface lying between the first distal outside circular surface and the outward end of the flanged portion  13  to be set inside the end cap  4  of the slider  2 . The second proximal outside circular surface is raised radially above the first distal outside circular surface to provide a radial gap  34  at a boundary between the first outside surface and the second outside surface. The radial gap  34  forms a stepwise edge  35  lying in perpendicular to the axial direction of the tubular holders  7 ,  8  so as to come into abutment against the relevant end surface  29  of the carriage  3  after the projections  20  have fitted deeply into the lengthwise slots  21 ,  22  and  23 . That is, the outside circular surfaces of the projections  20  of the tubular holders  7 ,  8  have the radial gaps  34  serving as the stepwise edges  35  which come into abutment against the end surfaces  29  of the carriage  3 . 
     With the tubular holders  7  and  8  constructed as stated earlier, the outside circular surfaces on the first distal portions of the projections  20  have threaded holes  28  which are used to firmly connect the holders  7 ,  8  to the carriage  3  through fastening screws  17  tightened from the outside of the carriage  3 . On an end surface of the flanged portion  13  axially opposite to the projections  20 , there is provided the bearing mounting  31  on which any one of the rolling-contact bearings  9 ,  10  is mounted. The bearing mountings  31  are each defined with the end surface of the flange portion  13  lying perpendicular to the axial direction of the tubular holder  7  or  8 , and the shoulder  33  reduced radially relative to the flanged portion  13  and extended axially from the end surface to fit into the inner ring of the rolling-contact bearing  9  or  10 . On the outside circular surfaces of the projections  20  of the tubular holders  7  and  8 , the gaps  34  are provided at the middle lengthwise of the projections  20 . The gaps  34  each have the stepwise edge  35  lying so as to come into abutment against the end surface  29  of the carriage  3 , making certain of accurate location of the relevant tubular holder  7  or  8 . The provision of the stepwise edges  35  envisaged coming into abutment or engagement with the end surfaces  29  of the carriage  3  makes it possible to fasten securely the tubular holders  7 ,  8  to the end surfaces of the slider  2  at the preselected locations where there remain small clearances to keep the flanged portions  13  of the tubular holders  7 ,  8  from engaging with or coming collision against the end surfaces of the end caps  4  of the slider  2 . 
     The shoulders  33  of the tubular holders  7 ,  8  each have an outside diameter identical with an inside diameter of the inner ring  15  of the rolling-contact bearing  9  or  10  while having an inside circular surface coplanar with the inside circular surface of the flanged portion  13  to form a cylinder extending integrally from the end surface of the flanged portion  13  in an axial direction of the flanged portion  13 . The tubular holder  7  has the cylindrical portion  19  which is further elongated from the cylinder of the flanged portion  13  in the axial direction. The cylindrical portion  19  is to carry a gear wheel thereon and terminates to the external threads  32 . Namely, the tubular holder  7  has the cylindrical portion  19  which is integral with the shoulder  33  and has the male threads  32  at the end thereof. Further the cylindrical portion  19  fits over the spline shaft  1  for free sliding movement relative to the spline shaft  1  and is equipped thereon with the rotary parts. Another tubular holder  8  has the shoulder  33  which is substantially equal in axial length or width to the axial width of the rolling-contact bearing  10 . The shoulders  33  as shown in  FIG. 4  each have an outside diameter which is determined to keep such a relation that the outside circular surface or the outside diameter of the outer ring of the rolling-contact bearing  9  or  10  mounted on the shoulder  33  is slightly raised above the outside circular surface or the outside diameter of the slider  2 . With the relation between the outside circular surfaces of the slider  2  and the bearings  9 ,  10  as stated just earlier, the slider  2  is protected from a possibility of interfering around the outside circular surface thereof with the machine frame  36  such as the component-placement heads and so on whenever the slider  2  is rotated. The end surfaces of the flanged portions  13  confronting to the bearings  9 ,  10  as shown in  FIG. 4  are at right angles relative to the lengthwise direction of the slider  2  so as to come into close engagement with end surfaces of the inner rings  15  of the bearing  9 ,  10  which have fitted over the bearing mountings  31  or shoulders  33 , thereby keeping in place the bearings  9 ,  10 . The end surfaces of the flanged portions  13  are cut relieved around a circular edge thereof so as not to touch end surfaces of the outer rings  14  of the bearings  9 ,  10 , thereby allowing the outer rings  14  of the bearings  9 ,  10  to rotate freely. 
     On the inside circular surface of the slider  2 , as shown in  FIG. 3 , there are provided the lengthwise slots  21 ,  22  and  23  to accommodate the projections  20  of the tubular holders  7 ,  8 . The slider  2  is composed of the carriage  3  of the cylindrical shell in which the spline shaft  1  fits for sliding movement, the carriage  3  having the second raceway grooves  24  cut in the inside circular surface thereof in opposition to the first raceway grooves  12  on the spline shaft  1 , the carriage  3  further having return passages  30  extending in parallel with the load-carrying raceways defined between the first and second raceway grooves  12  and  24 , the spacer parts  6  attached to the end surfaces of the carriage  3 , one to each end surface, and provided therein with inside curved halves  26  of the turnaround passages to connect the load-carrying races and their associated return passages  30 , and the end-cap major bodies  5  secured on the outward surfaces of the spacer parts  6  and provided therein with outside curved halves  25  of the turnaround passages. The end caps  4  are each constituted with a combination of the end-cap major body  5  and the spacer part  6 . The slider  2  of the present invention is more compact or slim in construction than ever because of having no end seals as opposed to the conventional sliders. 
     The slots  21 ,  22  and  23  in the slider  2  are designed to snugly fit over the projections  20  of the tubular holders  7 ,  8  and placed in diametrical opposition (180 degrees) on the inside circular surface to extend at right angles or 90 degrees relative to the raceway grooves  24 . With the carriage  3 , especially, the slots  21  or the first slots are made with the help of unused areas there is none of the raceway grooves  24 , the return passages  30  and threaded holes  18 . With the end-cap major bodies  3 , further, the slots  22  or the second slots are cut with the help of unused areas there is none of threaded or cored holes  46  and the raceway grooves  24  and the outside curved halves  25  of the turnaround passages. The spacer parts  6  has the slots  23  or the third slots which are made with the help of unused areas there is none of threaded or cored holes  46  and the inside curved halves  26  of the turnaround passages. The slots  21  in the carriage  3  have bottoms lying at an inside diameter in which the first outside circular surfaces of the projections  2 C are allowed to come into mating with the bottoms after the projections  20  have fitted deeply into the slots  21 . The slots  22 ,  23  in the end-cap major bodies  5  and the spacer parts  6  for the end caps  4  have bottoms lying at a common inside diameter in which the second outside circular surfaces of the projections  20  are allowed to come into mating with the bottoms. Moreover, the slots  22 ,  23  in the end-cap major bodies  5  and the spacer parts  6  for the end caps  4  are cut deeper than the slots  21  in the carriage  3  by as much as the radial gaps  34  on the projections  20 . All the slots  21  in the carriage  3 , slots  22  in the end-cap major bodies  5  and the slots  23  in the spacer parts  6  are in alignment with each other to allow the projections  20  of the tubular holders  7 ,  8  to extend through the slots  21 ,  22  and  23 . 
     On the outside circular surface of the carriage  3 , a pair of bolt holes is bored in opposition to the slots  21 . Fastening screws  17 , after having stretched through the holes, fit into threaded holes  28  in the projections  20  to fasten the tubular holders  7 ,  8  to the slider  2 . The spline shaft  1  of elongated cylinder has the raceway grooves  12  lying diametrically opposed to each other on a circular surface of the cylinder to extend lengthwise of the cylinder, and an axial through-hole  11  to communicate a pneumatic suction source to a nozzle head, not shown, which is mounted on the tip of the spline shaft  1  to pick up and then place components. 
     The ball-spline with rotary mechanism of the present invention is constructed as follows with the components as stated earlier. 
     First, the end caps  4  each composed of the end-cap major body  5  and the spacer part  6  are secured to the end surfaces  29  of the carriage  3 , one to each end surface, with the fastening screws  27  and at the same time the rolling elements of balls  45  are charged into the looped or closed circuits to complete the assembly of the slider  2 . Especially, the carriage  3  on the end surfaces  29  thereof has a pair of the threaded holes  18 , and the end-cap major bodies  5  and the spacer parts  6  to form the end caps  4  each have a pair of the cored holes  46  lying in opposition to the threaded holes  18  on the carriage  3 . Then, after keeping all the carriage  3 , spacer parts  6  and the end-cap major bodies  5  so as to bring their threaded holes  18  and cored holes  46  into line, the screws  27  stretch through the cored holes  46  when tightened and fit into the threaded holes  18  to clamp the spacer parts  6  and end-cap major bodies  5  together with the carriage  3  into the completed slider  2 . 
     In second phase, the projections  20  of the tubular holders  7 ,  8  are inserted into the slots  22 ,  23  and  21  from both the end surfaces of the slider  2  to a depth the stepwise edges  35  at the radial gaps  34  on the projections  20  come into abutment against the end surfaces  29  of the carriage  3 . Then, the fastening bolts  17  are tightened from the outside of the carriage  3  to fit into the threaded holes  28  in the projections  20  to complete the slider  2  having the tubular holders  7 ,  8  on the end surfaces thereof. For more firmly securing together the components stated earlier, moreover, any adhesives may be applied to mating surfaces of the carriage  3  with the projections  20  of the tubular holders  7 ,  8 . 
     In third phase, the spline shaft  1  fits into the slider  2  together with tubular holders. Then, the shoulder  31  or bearing mountings  33  are machined on the tubular holders  7 ,  8  in accurate concentricity with the spline shaft  1 . 
     In fourth phase, the rolling-contact bearings  9 ,  10  are held securely in place on the shoulder  31  or bearing mountings  31  whereby the ball-spline with rotary mechanism is wrought. 
     Referring now to  FIGS. 5 to 7 , there is shown a second version of the ball-spline with rotary mechanism according to the present invention. With the ball-spline with rotary mechanism of the second version, sliders  2 A and  2 B are spaced away from each other at a preselected interval on the spline shaft  1 . This version is preferable to an application in which the tip of the spline shaft  1  is subject to large momentum of force. 
     With the ball-spline with rotary mechanism of the second version in which the sliders  2 A,  2 B are opposed to each other on the spline shaft  1  in a way spaced at a preselected interval from each other, a cylindrical collar  37  interposed between the sliders  2 A,  2 B is fixed to inward ends of the sliders  2 A,  2 B. The tubular holders  7 ,  8  having the rolling-contact bearings  9 ,  10  fit over outward ends of the sliders  2 A,  2 B on the opposite side of the inward ends fastened to the cylindrical collar  37 . On lengthwise opposite ends of the cylindrical collar  37 , there are formed projections  39  like the projections  20  of the tubular holders  7 ,  8 . The projections  39 , after inserted into the slots  21 ,  22  and  23  in the sliders  2 A and  2 B, are clamped to the sliders  2 A,  2 B by means of the fastening screws  17  which stretch through the holes in the carriage  3  and fit into threaded holes  41  in the projections  39  to fasten the tubular holders  7 ,  8  to the slider  2 . 
     As seen in  FIG. 5 , the ball-spline with rotary mechanism according to the second version is composed of the sliders  2 A,  2 B opposed to each other on the elongated spline shaft  1  while spaced at a preselected interval from each other, the cylindrical collar  37  interposed between the sliders  2 A,  2 B and secured to inward ends of the sliders  2 A,  2 B, the tubular holder  7  having the rolling-contact bearing  9  which fits over the outward end of the slider  2 A on the opposite side of the inward end fastened to the cylindrical collar  37 , and the tubular holder  8  having the rolling-contact bearing  10  which fits over the outward end of the slider  2 B on the opposite side of the inward end fastened to the cylindrical collar  37 . The tubular holders  7  and  8  have the same construction as in the first version stated earlier. The sliders  2 A and  2   b  have the same dimension as in the standard product and the carriage  3  has the same length as in the standard product. Thus, the sliders  2 A and  2 B are less in length as compared with the slider  2  in the first version. The slots  21 ,  22  and  23  in the sliders  2 A and  2 B, namely, the slots  21  or the first slots in the carriages  3  and the slots  22 ,  23  in the spacer parts  6  and the end-cap major bodies  5  for the end caps  4  are constructed as with the slots in the first version. 
     The second version features the distinctive construction of the collar  37 . As shown in  FIGS. 6 and 7 , the collar  37  includes a cylindrical major portion  38  of a preselected length extending between the inward ends of the sliders  2 A and  2 B opposing to each other, and a pair of projections  39  extending integrally out of lengthwise opposite ends of the cylindrical major portion  38 . An inside circumferential surface  44  of the cylindrical major portion  38  merges with the inside circumferential surfaces  44  of the projections  39  into a common coplanar inside circular surface  44  which extends without coming into touching the spline shaft  1  throughout as in the inside circular surfaces of the tubular holders  7 ,  8 . The projections  39  of the collar  37  have the same construction as in the projections  20  of the tubular holders  7 ,  8  in the first version. The projections  39  have the inside circumferential surfaces extending in coplanar with the inside circumferential surface of the cylindrical major portion  38 . Moreover, the projections  39  are placed in diametrical symmetry with each other or at 180 degrees away from each other. The projections  39  each have a rectangular configuration in transverse section perpendicular to the axial direction and have an outside circular surface sunken radially below an outside circular surface around the cylindrical major portion  38 . The projections  39  each include a first distal portion to fit deep into the slot  21  in the carriage  3  and a second proximal portion lying between the distal portion and the outward end of the cylindrical major portion  38  to fit into the slots  22 ,  23  inside the and cap  4  of the slider  2 A or  2 B. A second outside circular surface on the second proximal portion is raised radially above a first outside circular surface on the first distal portion to provide a radial gap  40  at a boundary between the first outside circular surface and the second outside circular surface. The radial gap  40  forms a stepwise edge  42  lying in perpendicular to the axial direction of the collar  37  so as to come into abutment against the relevant end surface  29  of the carriage  3  after the projections  39  have fitted deeply into the lengthwise slots  21 ,  22  and  23 . 
     Namely, the outside circular surfaces of the projections  39  have the radial gaps  40  serving as the stepwise edges  42  which are envisaged coming into abutment against the end surfaces  29  of the carriage  3 . The stepwise edges  42  at the radial gaps  40  on the outside surfaces of the projections  39 , when the projections  39  have been introduced or inserted into the sliders  2 A and  2 B, come into abutment or engagement with the end surface  29  of the carriage  3 , making certain of accurate location of the collar  37  at the preselected location where the collar  37  is fastened to the ends of the sliders  2 A,  2 B with remaining small clearances to keep the lengthwise ends of the cylindrical major portion  38  of the collar  37  away from engaging with or coming collision against the end surfaces of the end caps  4  of the sliders  2 A and  2 B. On the outside circular surfaces on the first distal portions of the projections  39  of the collar  37 , there are provided threaded holes  41  which are used to firmly connect the collar  37  to the sliders  2 A,  2 B through fastening screws  17  tightened from the outside of the carriage  3 . The outside circular surface around the cylindrical portion  38  of the collar  37  is made flush with the outside circular surfaces around the second proximal portions of the projections  39 . Thus, the projections  39  each have the outside circular surface sunken radially below the outside circular surface around the cylindrical major portion  38  of the collar  37 . 
     The ball-spline with rotary mechanism of the second version is constructed as follows. 
     First, the projections  39  of the collar  37  lying between the inward end surfaces of the sliders  2 A,  2 B are inserted into the slots  22 ,  23  and  21  of the sliders  2 A,  2 B to a depth the stepwise edges  42  at the radial gaps  40  on the projections  39  come into abutment against the end surfaces  29  of the carriage  3 . Then, the fastening bolts  17  are tightened from the outside of the carriage  3  to fit into the threaded holes  41  in the projections  39  to complete a tandem slider combined with the collar  37 . For more firmly securing together the components stated earlier, moreover, any adhesives may be applied to mating surfaces of the carriage  3  with the projections  39  of the collar  37 . 
     In second phase, the projections  20  of the tubular holder  7  are introduced into the slots  22 ,  23  and  21  from an outward end surface of the slider  2 A to a depth the stepwise edges  35  at the radial gaps  34  on the projections  20  come into abutment against the end surfaces  29  of the carriage  3 . Then, the fastening bolts  17  are tightened from the outside of the carriage  3  to fit into the threaded holes  28  in the projections  20  to secure the holder  7  to the end surface of the slider  2 A. The projections  20  of another tubular holder  8  are inserted into the slots  22 ,  23  and  21  from an outward end surface of the slider  2 B to a depth the stepwise edges  35  at the radial gaps  34  on the projections  20  come into abutment against the end surfaces  29  of the carriage  3 . Then, the fastening belts  17  are tightened from the outside of the carriage  3  to fit into the threaded holes  28  in the projections  20  to secure the holder  8  to the end surface of the slider  2 B to thereby complete the combined sliders  2 A,  2 B together with the tubular holders. For more firmly joining together the sliders  2 A,  2 B and the tubular holders  7 ,  8 , moreover, any adhesives may be applied to mating surfaces of the slots  21  and the projections  21 . 
     In third phase, the spline shaft  1  fits into the sliders  2 A,  2 B with the tubular holders. Then, the bearing mountings  31  are machined on the tubular holders  7 ,  8  in accurate concentricity with the spline shaft  1  to provide a ball-spline with the holders having the concentric bearing mountings  31  thereon. 
     In fourth phase, the rolling-contact bearings  9 ,  10  are held securely in place on the bearing mountings  31  whereby the ball-spline with rotary mechanism is wrought according to the second version.