Patent Abstract:
An apparatus holds a plurality of hollow cylindrical members and pushes off the hollow cylindrical members. The apparatus includes a holder shaft for holding the hollow cylindrical members in tandem thereon, a gripper member projecting outwardly from a side wall surface of the holder shaft and engaging an inner wall surface of a foremost one of the hollow cylindrical members, a cam disposed in the holder shaft for displacing the gripper member, a pusher cylinder for pressing an end face of a rearmost one of the hollow cylindrical members and moving all the hollow cylindrical members forward, to release the foremost one of the hollow cylindrical members from the holder shaft and position a next one of the hollow cylindrical members as a new foremost one of the hollow cylindrical members, and a turning cylinder for turning the holder shaft.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for pushing a plurality of hollow cylindrical members into predetermined positions, respectively. 
     2. Description of the Related Art 
     As well known in the art, cylinder blocks manufactured in the automotive industry are a component of an internal combustion engine used as a propulsive source for automobiles. In many cases, cylinder sleeves are inserted in respective bores defined in the cylinder block. When the internal combustion engine is in operation, pistons which move back and forth in the respective cylinder bores have their outer side wall surfaces held in sliding contact with the inner wall surfaces of the cylinder sleeves. 
     The cylinder sleeves are inserted in the respective bores by insert casting. Specifically, after the cylinder sleeves are placed in given positions within a casting mold, a molten metal is poured into the casting mold around the cylinder sleeves, and then cooled into a solid cylinder block with the cylinder sleeves enveloped therein. 
     One known apparatus for inserting cylinder sleeves into given positions within a casting mold is disclosed in Japanese Laid-Open Patent Publication No. 2000-197954. The disclosed inserting apparatus has a first inserting mechanism for inserting cylinder sleeves into respective portions in a V-type internal combustion engine in which at least two bores are arranged in a V-shaped configuration, and a second inserting mechanism for inserting cylinder sleeves into respective portions in a straight internal combustion engine in which all the bores are aligned inline. The first inserting mechanism has a lower inserting unit and an upper inserting unit. For example, for a six-cylinder V-type internal combustion engine in which two sets of three bores are arranged in parallel, three cylinder sleeves are inserted into one array of three cylinders with the lower inserting unit, and other three cylinder sleeves are inserted into another array of three cylinders with the upper inserting unit. 
     In an inserting apparatus constituted as the one disclosed in Japanese Laid-Open Patent Publication No. 2000-197954, if the number of engine cylinders involved increases, then the number of cylinder sleeves to be held by the lower inserting mechanism or the upper inserting mechanism needs to be increased. As a result, the disclosed inserting apparatus becomes more complex in structure and greater in weight. The process of servicing the inserting apparatus for maintenance also becomes tedious and time-consuming. 
     In addition, the inserting apparatus includes a sleeve supply station having two different sleeve supply mechanisms for supplying cylinder sleeves to the first inserting mechanism and the second inserting mechanism. The two different sleeve supply mechanisms tend to make the inserting apparatus complex in structure. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a hollow cylindrical member pushing apparatus which is relatively simple in structure and is capable of inserting hollow cylindrical members easily into predetermined positions. 
     To achieve the above object, there is provided in accordance with the present invention an apparatus for holding a plurality of hollow cylindrical members and pushing off the hollow cylindrical members, comprising a holder shaft for holding the hollow cylindrical members in tandem thereon, a gripper member projecting outwardly from a side wall surface of the holder shaft and engaging an inner wall surface of a foremost one of the hollow cylindrical members held on the holder shaft, a cam disposed in the holder shaft for displacing the gripper member, pushing means for pressing an end face of a rearmost one of the hollow cylindrical members held by the holder shaft and moving all the hollow cylindrical members forward, to release the foremost one of the hollow cylindrical members from the holder shaft and position a next one of the hollow cylindrical members as a new foremost one of the hollow cylindrical members on the holder shaft, and turning means for turning the holder shaft. 
     The hollow cylindrical members that are held in tandem mean that the hollow cylindrical members are kept end to end on the holder shaft. 
     The holder shaft can hold at least two hollow cylindrical members thereon and allows the hollow cylindrical members to be individually released therefrom. As the number of holder shafts does not need to be increased depending on the total number of hollow cylindrical members involved, the apparatus, i.e., the hollow cylindrical member pushing apparatus, is simple in structure, light in weight, and low in cost. Since the hollow cylindrical member pushing apparatus is simple in structure, it can easily be serviced for maintenance. 
     Inasmuch as the holder shaft is capable of holding a plurality of hollow cylindrical members, the hollow cylindrical member pushing apparatus can smoothly push and insert the hollow cylindrical members into predetermined positions. 
     After the foremost one of the hollow cylindrical members is released from the holder shaft and the next one of the hollow cylindrical members is positioned as the new foremost one of the hollow cylindrical members on the holder shaft, the turning means is actuated to turn the holder shaft, and then the pushing means pushes the end face of the rearmost one of the hollow cylindrical members to release only the new foremost one of the hollow cylindrical members from the holder shaft. The hollow cylindrical members thus released can be placed in different positions. 
     The hollow cylindrical member pushing apparatus may have a plurality of holder shafts. The plural holder shafts make it possible to hold and push more hollow cylindrical members simultaneously. 
     Each of the hollow cylindrical members may comprise a cylinder sleeve to be enclosed in a cylinder block by insert casting. 
     According to the present invention, the holder shaft holds the hollow cylindrical members in tandem and allows the hollow cylindrical members to be individually released therefrom. As the number of holder shafts does not need to be increased depending on the total number of hollow cylindrical members involved, the hollow cylindrical member pushing apparatus is simple in structure. 
     After the foremost hollow cylindrical member is released from the hollow shaft, the turning means operates to turn the hollow shaft, and then the next hollow cylindrical member is released from the hollow shaft. Accordingly, the hollow cylindrical members which are individually released from the holder shaft can be placed in different positions. 
     The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view, partly in cross section, of a hollow cylindrical member pushing apparatus according to an embodiment of the present invention; 
         FIG. 2  is a plan view, partly cut away, of the hollow cylindrical member pushing apparatus shown in  FIG. 1 ; 
         FIG. 3  is an enlarged side elevational view, partly in cross section and cut away, of a third holder shaft; 
         FIG. 4  is a schematic diagram, partly in cross section and cut away, showing the manner in which first through third holder shafts are in a standby position before they hold respective cylinder sleeves; 
         FIG. 5  is a schematic diagram, showing the manner in which the first through third holder shafts hold respective cylinder sleeves of a first array; 
         FIG. 6  is a schematic diagram, showing the manner in which the first through third holder shafts are retracted while holding the respective cylinder sleeves of the first array; 
         FIG. 7  is a schematic diagram, showing the manner in which the first through third holder shafts hold respective cylinder sleeves of a second array; 
         FIG. 8  is a schematic diagram, showing the manner in which the first through third holder shafts are retracted while holding the respective cylinder sleeves of the second array; 
         FIG. 9  is a schematic diagram, showing the manner in which the first through third holder shafts face respective retainer pins to which the respective cylinder sleeves of the second array are to be transferred; 
         FIG. 10  is a plan view, partly in cross section and cut away, showing the manner in which the respective cylinder sleeves of the second array are individually transferred from the first through third holder shafts to the respective retainer pins; 
         FIG. 11  is a plan view, partly in cross section and cut away, showing the manner in which the first through third holder shafts face respective retainer pins to which the respective cylinder sleeves of the first array are to be transferred; and 
         FIG. 12  is a plan view, partly in cross section and cut away, showing the manner in which the respective cylinder sleeves of the first array are individually transferred from the first through third holder shafts to the respective retainer pins. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A hollow cylindrical member pushing apparatus according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the embodiment described below, cylinder sleeves for use in an engine cylinder block will be illustrated as hollow cylindrical members. 
       FIG. 1  is a side elevational view, partly in cross section, of a hollow cylindrical member pushing apparatus  10  according to the present embodiment, and  FIG. 2  is a plan view, partly cut away, of the hollow cylindrical member pushing apparatus  10  shown in  FIG. 1 . The hollow cylindrical member pushing apparatus  10  has a first holder shaft  12   a , a second holder shaft  12   b , and a third holder shaft  12   c , to be described later, for holding cylinder sleeves. In  FIG. 1 , the first holder shaft  12   a , the second holder shaft  12   b , and the third holder shaft  12   c  are shown as being in a central position in their angularly movable range. In  FIG. 2 , the first holder shaft  12   a , the second holder shaft  12   b , and the third holder shaft  12   c  are shown as being fully angularly moved in their angularly movable range. 
     Each of the first holder shaft  12   a , the second holder shaft  12   b , and the third holder shaft  12   c , which are arrayed parallel to each other, can hold two cylinder sleeves  14   a ,  14   b  in tandem, i.e., end to end. The hollow cylindrical member pushing apparatus  10  has a support block  18  which supports the first holder shaft  12   a , the second holder shaft  12   b , and the third holder shaft  12   c  on respective attachment jigs  16 . The first holder shaft  12   a , the second holder shaft  12   b , and the third holder shaft  12   c  extend horizontally from the support block  18  and are successively arrayed vertically in this order. 
     The cylinder sleeves  14   a ,  14   b  are identical in structure and shape to each other. For illustrative purpose, the cylinder sleeve denoted “14 a ” is supported closely to the proximal end of each of the first holder shaft  12   a , the second holder shaft  12   b , and the third holder shaft  12   c  and positioned as a rearmost one. The cylinder sleeve denoted “14 b ” is supported closely to the distal end of each of the first holder shaft  12   a , the second holder shaft  12   b , and the third holder shaft  12   c  and positioned as a foremost one. 
       FIG. 3  shows the third holder shaft  12   c  by way of illustrative example. As shown in  FIG. 3 , the third holder shaft  12   c  includes a smaller-diameter portion  20 , a tapered portion  22 , and a larger-diameter portion  24  which are successively arranged from its distal end toward its proximal end. The larger-diameter portion  24  is coupled to the support block  18  by the attachment jig  16 . The first holder shaft  12   a , the second holder shaft  12   b , and the third holder shaft  12   c  are mounted on the support block  18  by a floating structure. 
     A cylindrical positioning knob  26  is disposed on the outer front end surface of the distal end of the smaller-diameter portion  20 . The third holder shaft  12   c  is of a hollow structure with a rod-shaped shank  28  extending coaxially therein. The rod-shaped shank  28  supports a presser cam  30  mounted thereon within the smaller-diameter portion  20 . The presser cam  30  has a tapered surface  32  facing toward the distal end of the smaller-diameter portion  20 . 
     The smaller-diameter portion  20  supports a pair of diametrically opposite, i.e., 180°-spaced, axially movable gripper pins (gripping members)  34  having respective outer ends projecting radially outwardly from outer side wall surfaces of the smaller-diameter portion  20 . The gripper pins  34  have respective inner ends positioned within the smaller-diameter portion  20  and having respective tapered surfaces  36  held in sliding contact with the tapered surface  32  of the presser cam  30 . The presser cam  30  and the gripper pins  34 , described above, are positioned closely to the distal end of the smaller-diameter portion  20 . The smaller-diameter portion  20  supports another pair of diametrically opposite, i.e., 180°-spaced, axially movable gripper pins (gripping members)  34  positioned closely to the proximal end of the smaller-diameter portion  20 . 
     A spring retainer, not shown, is mounted on the rod-shaped shank  28  within the larger-diameter portion  24 . A helical spring, also not shown, is placed between the spring retainer and the larger-diameter portion  24  for normally biasing the rod-shaped shank  28  to move in a direction toward the cylindrical positioning knob  26 . 
     The distance between the outer front end surface of the distal end of the smaller-diameter portion  20  and the boundary between the tapered portion  22  and the larger-diameter portion  24  is substantially the same as the axial length of the cylinder sleeve  14   b . Similarly, the distance between the boundary between the tapered portion  22  and the larger-diameter portion  24  and the distal end of the attachment jig  16  is also substantially the same as the axial length of the cylinder sleeve  14   a.    
     The attachment jig  16  is combined with a sensor  37  for detecting whether the cylinder sleeve  14   a  is held on the third holder shaft  12   c  or not. 
     Since the first holder shaft  12   a  and the second holder shaft  12   b  are identical to the third holder shaft  12   c , the first holder shaft  12   a  and the second holder shaft  12   b  will not be described in detail below. 
     As shown in  FIG. 1 , the support block  18  comprises a first horizontal portion  38 , an upstanding portion  40  extending upwardly from the first horizontal portion  38 , and a second horizontal portion  42  extending from an upper end of the upstanding portion  40  parallel to the first horizontal portion  38 . The support block  18  is of an essentially C-shaped structure as viewed in side elevation. A turning cylinder  44  as a turning means for angularly moving the first through third holder shafts  12   a ,  12   b ,  12   c  together with the support block  18  is disposed between the first horizontal portion  38  and the second horizontal portion  42 . 
     As shown in  FIG. 2 , the turning cylinder  44  is enclosed in a casing  46  and has an end supported on the casing  46  by a joint shaft  47 . In the illustrated embodiment, the turning cylinder  44  is slightly offset upwardly from the longitudinal central axis of the casing  46 . 
     The turning cylinder  44  has a piston rod  48  connected to a first link  49  that is operatively connected to a second link  50 . As shown in  FIGS. 1 and 2 , a first bar  52  is inserted into the first link  49 . The first bar  52  rotatably supports the connection between the first link  49  and the second link  50 . 
     The second link  50  has one end connected to the first link  49  and the other end which is spaced from the extending direction of the piston rod  48 . A second bar  54  extends vertically through a through hole defined in the other end of the second link  50  and also extends from an upper surface of the first horizontal portion  38  to an lower surface of the second horizontal portion  42  through the casing  46 . The casing  46  and the support block  18  are supported. In  FIG. 1 , reference numeral  55  designates a bearing. 
     As shown in  FIG. 1 , the first horizontal portion  38  and the second horizontal portion  42  house therein a first pusher cylinder  56  and a second pusher cylinder  58 , respectively, each serving as a pushing means. The first pusher cylinder  56  has a piston rod  60  connected to a first pusher guide  62 . The first pusher guide  62  covers the attachment jig  16  coupled to the first holder shaft  12   a  and the attachment jig  16  coupled to the second holder shaft  12   b . The second pusher cylinder  58  has a piston rod  64  fitted into a second pusher jig  66  which is inverted-L-shaped as viewed in side elevation. 
     A hollow cylindrical second pusher guide  68  is fitted over the attachment jig  16  coupled to the third holder shaft  12   c . The second pusher guide  68  has a radially outwardly extending flange  70  on its axially intermediate portion. The flange  70  is held in abutting engagement with the first pusher guide  62  at a position which is diametrically opposite to, i.e., 180°-spaced from, the position where the flange  70  is also held in abutting engagement with the second pusher jig  66 . 
     The hollow cylindrical member pushing apparatus  10  according to the present embodiment is basically constructed as described above. Operation and advantages of the hollow cylindrical member pushing apparatus  10  will be described below. 
     As shown in  FIG. 4 , while the hollow cylindrical member pushing apparatus  10  is being retracted from a sleeve supply mechanism  80 , a set of three cylinder sleeves  14   a  is supplied to the sleeve supply mechanism  80 . Then, as shown in  FIG. 5 , the hollow cylindrical member pushing apparatus  10  is displaced to the sleeve supply mechanism  80  to insert the first through third holder shafts  12   a ,  12   b ,  12   c  into the respective cylinder sleeves  14   a . When the smaller-diameter portions  20  of the first through third holder shafts  12   a ,  12   b ,  12   c  are inserted respectively into the cylinder sleeves  14   a , the inner wall surfaces of the cylinder sleeves  14   a  press the gripper pins  34  radially inwardly. The gripper pins  34  are retracted radially inwardly into the smaller-diameter portions  20 , causing the tapered surfaces  36  to push the corresponding tapered surfaces  32  of the presser cams  30  in sliding contact therewith. The presser cams  30  and hence the rod-shaped shank  28  are axially displaced rearward, whereupon the spring retainer on the rod-shaped shank  28  compresses the helical spring. 
     Thereafter, as shown in  FIG. 6 , the hollow cylindrical member pushing apparatus  10  is retracted from the sleeve supply mechanism  80 . At the same time, the sleeve supply mechanism  80  is supplied with a new set of three cylinder sleeves  14   b.    
     The hollow cylindrical member pushing apparatus  10  is displaced again toward the sleeve supply mechanism  80  to insert the first through third holder shafts  12   a ,  12   b ,  12   c  into the respective cylinder sleeves  14   b . When the smaller-diameter portions  20  of the first through third holder shafts  12   a ,  12   b ,  12   c  are inserted respectively into the cylinder sleeves  14   b , as shown in  FIG. 7 , the cylinder sleeves  14   b  push the previously installed cylinder sleeves  14   a  to a position over the larger-diameter portions  24  of the first through third holder shafts  12   a ,  12   b ,  12   c . Now, two cylinder sleeves  14   a ,  14   b  are retained on each of the first through third holder shafts  12   a ,  12   b ,  12   c , so that a total of six cylinder sleeves are retained on the first through third holder shafts  12   a ,  12   b ,  12   c.    
     Then, as shown in  FIG. 8 , the hollow cylindrical member pushing apparatus  10  is spaced away from the sleeve supply mechanism  80 . Thereafter, as shown in  FIG. 9 , the hollow cylindrical member pushing apparatus  10  is moved to a casting mold assembly  82 . The casting mold assembly  82  has a total of six holder pins  84   a  through  84   f  for holding cylinder sleeves  14   a ,  14   b . Specifically, the casting mold assembly  82  includes an array of three parallel holder pins  84   a ,  84   b ,  84   c  and another array of three parallel holder pins  84   d ,  84   e ,  84   f.    
     The first through third holder shafts  12   a ,  12   b ,  12   c  of the hollow cylindrical member pushing apparatus  10  are initially held in facing relation to the holder pins  84   a ,  84   b ,  84   c , respectively, in axial alignment therewith. At this time, the piston rod  48  of the turning cylinder  44  is fully extended over its maximum stroke. 
     The holder pins  84   a  through  84   f  have respective smaller-diameter holding end portions  86 . The smaller-diameter holding end portions  86  have respective recesses  88  defined in their respective end faces. The cylindrical positioning knobs  26  of the first, second, and third holder shafts  12   a ,  12   b ,  12   c  are placed respectively in the recesses  88  of the holder pins  84   a ,  84   b ,  84   c . As shown in  FIG. 10 , the piston rods  60 ,  64  of the first pusher cylinder  56  and the second pusher cylinder  58  are synchronously extended. The piston rod  60  of the first pusher cylinder  56  causes the first pusher guide  62 , and the piston rod  64  of the second pusher cylinder  58  causes the second pusher jig  66  and the second pusher guide  68 , to push the cylinder sleeves  14   a  which have initially been held on the first, second, and third holder shafts  12   a ,  12   b ,  12   c . When the cylinder sleeves  14   a  are pushed along the first, second, and third holder shafts  12   a ,  12   b ,  12   c , they push the subsequently held cylinder sleeves  14   b  off the first, second, and third holder shafts  12   a ,  12   b ,  12   c  onto the smaller-diameter holding end portions  86  of the holder pins  84   a ,  84   b ,  84   c.    
     After the cylinder sleeves  14   b  are fitted over the smaller-diameter holding end portions  86  of the holder pins  84   a ,  84   b ,  84   c , the hollow cylindrical member pushing apparatus  10  is displaced to a predetermined position, and the piston rod  48  of the turning cylinder  44  is retracted. Since the first link  49  is coupled to the one end of the second link  50  by the first bar  52  and the other end of the second link  50  is coupled to the casing  46  and the support block  18  by the second bar  54 , the support block  18  is angularly moved about the second bar  54  until the first through third holder shafts  12   a ,  12   b ,  12   c  brought into facing relation to the holder pins  84   d ,  84   e ,  84   f , respectively, in axial alignment therewith, as shown in  FIG. 11 . 
     Then, the piston rods  60 ,  64  of the first pusher cylinder  56  and the second pusher cylinder  58  are synchronously extended. As shown in  FIG. 12 , the initially held cylinder sleeves  14   a  are pushed off the first, second, and third holder shafts  12   a ,  12   b ,  12   c  onto the smaller-diameter holding end portions  86  of the holder pins  84   d ,  84   e ,  84   f.    
     At the same time, the helical springs resiliently urge the respective spring retainers on the rod-shaped shanks  28  of the first, second, and third holder shafts  12   a ,  12   b ,  12   c , moving the rod-shaped shanks  28  toward the distal ends thereof. The tapered surfaces  32  of the presser cams  30  slidingly push the tapered surfaces  36  of the gripper pins  34 , causing the gripper pins  34  to move radially outwardly in directions to project from the first, second, and third holder shafts  12   a ,  12   b ,  12   c.    
     According to the present embodiment, as described above, each of the first, second, and third holder shafts  12   a ,  12   b ,  12   c  can hold two cylinder sleeves  14   a ,  14   b  in tandem, and the two cylinder sleeves  14   a ,  14   b  can individually be released from each of the first, second, and third holder shafts  12   a ,  12   b ,  12   c . As the number of holder shafts does not need to be increased depending on the total number of cylinder sleeves involved, the hollow cylindrical member pushing apparatus  10  is simple in structure, light in weight, and low in cost. Since the hollow cylindrical member pushing apparatus  10  is simple in structure, it can easily be serviced for maintenance. 
     In the illustrated embodiment, the hollow cylindrical member pushing apparatus  10  has three holder shafts  12   a ,  12   b ,  12   c . However, the hollow cylindrical member pushing apparatus according to the present invention may have one or two holder shafts or more than three holder shafts. 
     In the illustrated embodiment, the cylinder sleeves  14   a ,  14   b  are illustrated as hollow cylindrical members. However, other members may be used as hollow cylindrical members. The hollow cylindrical member pushing apparatus  10  is not limited to being used with the casting mold assembly  82 , but may be used in combination with other apparatus. 
     In the illustrated embodiment, each of the holder shafts includes two longitudinally spaced pairs of circumferentially spaced gripper pins  34 , which means that the four gripper pins  34  are provided in total. However, each of the holder shafts may include three or more longitudinally spaced sets of three or more circumferentially spaced gripper pins  34 . 
     Each of the first, second, and third holder shafts  12   a ,  12   b ,  12   c  may be of an axially increased length for holding three or more cylinder sleeves or hollow cylindrical members. The hollow cylindrical member pushing apparatus with the longer holder shafts for holding three or more cylinder sleeves or hollow cylindrical members operates as follows: When the piston rods  60 ,  64  are extended, the rearmost cylinder sleeves or hollow cylindrical members are pushed thereby, so that all the cylinder sleeves or hollow cylindrical members on the holder shafts are moved toward the distal ends thereof. The foremost cylinder sleeves or hollow cylindrical members are then released from the holder shafts. The next sleeves or hollow cylindrical members, which follow the released cylinder sleeves or hollow cylindrical members, are now positioned as new foremost cylinder sleeves or hollow cylindrical members on the holder shafts. 
     The piston rods  60 ,  64  are further extended to push the rearmost cylinder sleeves or hollow cylindrical members. All cylinder sleeves or hollow cylindrical members on the holder shafts are moved toward the distal ends thereof until the new foremost cylinder sleeves or hollow cylindrical members are released from the holder shafts. 
     The above operation is repeated until the rearmost cylinder sleeves or hollow cylindrical members come to the foremost position on the holder shafts. The piston rods  60 ,  64  are extended to push the rearmost cylinder sleeves or hollow cylindrical members until they are released from the holder shafts. In this manner, all the cylinder sleeves or hollow cylindrical members are pushed off the holder shafts. 
     Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.

Technology Classification (CPC): 1