Abstract:
To provide a pin tip attachment structure that can seize a container with bottom such as a can or bottle, and convey the container without scratching it, a small diameter portion having a predetermined length is formed at a front end portion of a pin; a bush is provided, the bush being fitted in a lower end portion of a cylindrical hole of a pin tip having the cylindrical hole opened at a lower end side, and vertically movably fitted with the periphery of the small diameter portion in an insertional manner; a stopper portion for retaining the bush is provided at a front end of the small diameter portion; a spring receiver portion is provided below the small diameter portion; and a coil spring is provided in a compressible manner between the spring receiver portion and the bush or the lower end of the pin tip.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a structure for stretching a pin of a chain and attaching a pin tip to an end of the pin, the chain being for seizing and conveying a container with bottom such as can or bottle. 
         [0003]    2. Related Art 
         [0004]    Recently, aluminum or steel cans have been often used for containers of drinks such as beer or juice. A large number of the cans are manufactured and bottled with drinks in factories. When the cans are manufactured, many steps such as a printing step on an outer circumferential face, drying step, and coating step of the inside are necessary. In each of the steps, the cans are conveyed by a pin chain conveyor.  FIG. 9  shows aluminum cans  102  being conveyed seized to pin tips  101  of a pin chain conveyor  100 . Of course, steel cans are conveyed in the same way. 
         [0005]    Speed of the aluminum cans  102  being conveyed seized to the pin tips  101  of the pin chain conveyor  100  is extremely fast, about 200 m/min. Therefore, since the aluminum cans  102  seized to the pin tips  101  are moving without rest, scratches are induced on the insides of the cans by rubbing of the cans with the pin tips  101 . The scratches cause imperfect coating of the inside of the aluminum cans. As a result, corrosion is induced by bottled drinks, resulting in reduction in quality of the drinks bottled in the aluminum cans  102 . 
         [0006]    The “pin chain conveyor” disclosed in JP-A-7-149417 is configured to be able to prevent deformation of an opened edge of a can. That is, a pin chain conveyor has a chain to be conveyed, pins projecting from the chain, pin tips to be attached to ends of the pins, the pin tips being reversely covered with cylinders with bottom and having a cylindrical outside; wherein size of length of the pin tips is formed large compared with size of height of the cylinders with bottom, and end portions at a chain side of the pin tips are formed in a taper shape having a tapered end. However, while the opened edges of the cylinders with bottom seized to such pin tips are not deformed during being conveyed, scratches cannot be prevented from being induced on the inside. 
         [0007]      FIGS. 10A to 10C  show a conventional attachment structure of a pin tip attached to a pin. A pin tip  104  shown in  FIG. 10A  has a small outer diameter size, and directly pressed to fit with a pin  103 . In some cases, a retention process is performed to prevent separation of the pin tip  104  from the pin  103 . 
         [0008]    A pin tip  105  shown in  FIG. 10B  has a reverse truncated cone shape, and is set on a coil spring  107  being set on and supported thereby a ring plate  106  attached to the pin  103 . A fixing tool  108  is attached to a front end of a pin such that the pin tip  105  is not separated from the pin  103 . Accordingly, the pin tip  105  can fall while compressing the coil spring  107  by load exerted from above, so that the aluminum can  102  being conveyed can be supported and conveyed without receiving an impact. 
         [0009]    An attachment structure of a pin tip  109  shown in  FIG. 10   c  is in common with that of  FIG. 10B , however, the coil spring  107  and the ring plate  106 , which support the pin tip  109 , are configured to be accommodated in a recess formed at a lower end portion of the pin tip  109 . Therefore, the structure has an appearance that the coil spring  107  and the ring plate  106  are not exposed outside of the pin tip  9 . 
         [0010]    If the pin tips  105  and  109  are supported by the coil spring  107  as shown in  FIGS. 10B and 10C , when load is exerted, the coil spring  107  is compressed and deformed so that the pin tips  105  and  109  can slide and fall along the pin  103 , which prevents scratches from being induced on the inside of the aluminum can  102  being conveyed. However, such an attachment structure cannot be used for the pin tip  104  having a small size as shown in  FIG. 10A  Therefore, there has been a difficulty that the large pin tip  105  or  109  as shown in  FIGS. 10B  or  10 C cannot be used for conveying a bottle can having a small port, consequently impact force is exerted between the pin tip and the aluminum can  102  being conveyed, causing scratches on the inside of the can. 
       SUMMARY OF THE INVENTION 
       [0011]    It is desirable to provide a pin tip attachment structure of a chain for can making, which can support a pin tip by a coil spring even if the pin tip is a small pin tip that can support a container having a small port. 
         [0012]    Thus, a pin tip attachment structure according to an embodiment of the invention is in a configuration where a small diameter portion having a predetermined length is formed at an end portion of a pin; a bush is provided, the bush being fitted in a lower end portion of a cylindrical hole of a pin tip having the cylindrical hole opened at a lower end side, and vertically movably fitted with the periphery of the small diameter portion in an insertional manner; a stopper portion for retaining the bush is provided at a front end of the small diameter portion; a spring receiver portion is provided below the small diameter portion; and a coil spring is provided in a compressible manner between the spring receiver portion and the bush or the lower end of a pin tip. 
         [0013]    According to such a configuration, since the pin tip is supported by the coil spring, and can be vertically moved with stretch and contraction of the coil spring within a range of the small diameter portion of the pin, when an upper end of the pin tip is pressed, the coil spring is compressed and falls. At that time, the bush slides with the small diameter portion as a guide. Here, it is preferable that the cylindrical hole of the pin tip is made to have a step, and the lower end portion of the hole, which is to be fitted with the bush, is made to have a slightly large diameter, and an upper side of the hole is made to have a smaller diameter for vertical movement of the stopper portion at a front end of the pin. 
         [0014]    The bush is preferably a bush with collar having a collar portion at a lower end because it is easily attached to the pin tip. Moreover, when a slit groove is formed in the bush in a longitudinal direction so that inner diameter of a hole of the bush can be expanded, even if the stopper portion is fixed, the bush can override the stopper portion and can be fitted with the small diameter portion of the pin in the insertional manner. 
         [0015]    The spring receiver portion can be a ring plate attached to the periphery of the pin, or may be formed by forming a receiver base using a step on the periphery of the pin. 
         [0016]    The stopper portion can be formed by press fitting and fixing of a sleeve with respect to the pin, or can be formed by forming a screw thread at the front end of the pin and then screwing a nut with the thread. According to such a configuration, the stopper portion can be attached to the front end of the pin after attaching the bush irrespective of a shape of the bush, and therefore assembly operation is facilitated. 
         [0017]    The stopper portion may be a large diameter portion integrally formed with the pin, and in this case, a bush having a slit groove formed in a longitudinal direction is used. 
         [0018]    According to the pin tip attachment structure of the invention, since the pin tip can be supported while being set on the coil spring even if the pin tip is small, when a container is seized, the coil spring is compressed and deformed and consequently an impact is mitigated even if the container has a small port, which eliminates scratches induced on the inside of a can or bottle. 
         [0019]    On the other hand, the can or bottle extremely objects to adhesion of oils and fats because it contains drinks, or when the oils and fats are adhered on the inside of the can or bottle, coating performance of paint becomes worse, however, the pin tip attachment structure of the invention is configured in a way that the pin is attached with the coil spring or the bush, and the pin tip can be finally attached. Accordingly, the structure of the invention is advantageous in that possibility of adhesion of oils and fats to the pin tip is extremely reduced, and consequently adhesion of oils and fats to the inside of a can or bottle is suppressed. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIGS. 1A and 1B  show vertical section views showing a pin tip attachment structure according to a first embodiment of the invention, which represent a case that a pin tip is in a rising position and a case that it is in a falling position respectively; 
           [0021]      FIGS. 2A ,  2 B and  2 C show vertical section views showing a front-end portion of a pin to be attached with a pin tip in the structure, and a condition where a coil spring is attached to the end portion and a condition where a bush with collar is attached to the end portion, respectively; 
           [0022]      FIGS. 3A and 3B  show a front view and a plane view showing the bush with collar in the structure, respectively; 
           [0023]      FIGS. 4A and 4B  show vertical section views showing a pin tip attachment structure according to a second embodiment of the invention, which represent a case that a pin tip is in a rising position and a case that it is in a falling position respectively; 
           [0024]      FIGS. 5A and 5B  show vertical section views showing a pin tip attachment structure according to a third embodiment of the invention, which represent a case that a pin tip is in a rising position and a case that it is in a falling position respectively; 
           [0025]      FIGS. 6A and 6B  show vertical section views showing a pin tip attachment structure according to a fourth embodiment of the invention, which represent a case that a pin tip is in a rising position and a case that it is in a falling position respectively; 
           [0026]      FIGS. 7A ,  7 B and  7 C show vertical section views showing a different embodiment of the front end portion of the pin in the structures, which represent the front end portion of the pin to be attached with a pin tip, a condition where a coil spring is attached to the front end portion, and a condition where a bush with collar is attached to the front end portion, respectively; 
           [0027]      FIGS. 8A and 8B  show plane views showing a condition where the pin tip seizes an aluminum can, and a condition where it seizes an aluminum bottle, using partial cross sections, respectively; 
           [0028]      FIG. 9  shows a schematic plane view showing a pin chain conveyor, and 
           [0029]      FIGS. 10A ,  10 B and  10 C show plane views showing usual pin tip attachment structures respectively. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]      FIGS. 1A and 1B  show a pin tip attachment structure according to a first embodiment of the invention, in which a reference  1  indicates a pin tip, reference  2  indicates a coil spring, reference  3  indicates a pin, reference  4  indicates a bush with collar, and reference  5  indicates a ring plate, respectively. The pin tip  1  is attached to the pin  3  in a stretchable and contractible manner by the coil spring  2  mounted on the pin  3 .  FIG. 1A  shows a case that the coil spring  2  is stretched and the pin tip  1  is therefore in a rising position, and  FIG. 1B  shows a case that the coil spring  2  is compressed and deformed and the pin tip  1  is therefore in a falling position. 
         [0031]    The pin tip  1  has a front end side formed in a semispherical shape, and has a cylindrical hole  1   a  opened at a lower end side in which the bush with collar  4  is fitted. At a front end portion  6  of the pin  3 , a thinned small-diameter portion  7  is formed, and a large diameter portion  8  having the same size as size of the pin  3  is integrally formed with a front end of the pin, as shown in  FIG. 2A . The ring plate  5  is attached to a lower side of the small-diameter portion  7 , and as shown in  FIG. 2B , the coil spring  2  is fitted with the periphery of the front-end portion  6  of the pin in an insertional manner and set on the ring plate  5 . Then, as shown in  FIG. 2C , the bush with collar  4  is attached retained by the large diameter portion  8  at the front end of the pin. 
         [0032]    As shown in  FIGS. 3A and 3B , the bush with collar  4  is in a configuration where a slit groove  9  is formed in a longitudinal direction, so that the inner diameter “d” of the groove can be expanded. In the bush with collar  4 , a collar portion  11  is formed at a lower end of a cylindrical bush portion  10 , and a hole  12  is formed through in an axial direction in the center. When the bush is fitted with the pin  3  in the insertional manner, first, the large diameter portion  8  of the front end of the pin is inserted into the hole  12 , and at that time, the slit groove  9  is expanded by the large diameter portion  8  of the pin, thereby the inner diameter “d” of the hole  12  is expanded to be at least the outer diameter “D” of the large diameter portion  8  of the pin (refer to  FIG. 2B ) and fit with the large diameter portion  8  in the insertional manner. 
         [0033]    Next, when the bush with collar  4  engaged with the large diameter portion  8  is further pushed down, the bush with collar  4  is fitted with the small diameter portion  7  in the insertional manner as shown in  FIG. 2C . At that time, the slit groove  9  that has been expanded by the large diameter portion  8  is returned to have an original width so that the inner diameter “d” of the bush  4  becomes smaller than the outer diameter “D” of the large diameter portion  8 . Then, the coil spring  2  is pinched between the ring plate  5  and the collar portion  11  and thus compressed. Therefore, the bush with collar  4  is forced up at any time by the coil spring  2 , and an upper end  13  of the bush is seized to a lower end of the large diameter portion  8  of the pin. The bush with collar  4  that has been pushed down and temporarily fitted with the small diameter portion  7  in the insertional manner is not disengaged because the inner diameter “D” of the hole  12  is smaller than the outer diameter “D” of the large diameter portion of the front end of the pin. 
         [0034]    The bush with collar  4  fitted with the pin  3  in the insertional manner in this way is fitted into a lower end of a cylindrical hole  1   a  of the pin tip  1 , thereby the pin tip  1  is attached to the pin  3  ( FIG. 1A ). Then, when the pin tip  1  is pressed, the coil spring  2  is compressed and deformed, thereby the pin tip  1  falls, and the collar portion  11  of the bush with collar  4  is contacted to a base  14  using a step formed at a lower side of the small diameter portion  7  of the pin  3 , thereby the pin tip  1  is stopped (refer to  FIG. 1B ). When pressing force is released, the coil spring  2  is stretched and the pin tip  1  rises as shown in  FIG. 1A . 
         [0035]      FIGS. 4A and 4B  show a pin tip attachment structure according to a second embodiment of the invention. While a basic structure is same as in the case of the first embodiment, the pin  3  does not have the ring plate  5 . Instead, a receiver base  18  for receiving the coil spring  2  is formed in the pin  3 , and the coil spring  2  rests on the receiver base  18 , and elastically supports the pin tip  1 .  FIG. 4A  shows a case that the coil spring  2  is stretched and thus the pin tip  1  is in a rising position, and  FIG. 4B  shows a case that the coil spring  2  is compressed and deformed and thus the pin tip  1  is in a falling position. 
         [0036]      FIGS. 5A and 5B  show a pin tip attachment structure according to a third embodiment of the invention. While a basic structure is same as in the case of the first embodiment, the structure is different in that a structure of the bush with collar  4  is configured by separate pieces of a bush part and a collar part. That is, a lower end of the bush part is fitted in a concave portion provided in a top of the collar part so that the bush with collar  4  is configured.  FIG. 5A  shows a case that the coil spring  2  is stretched and thus the pin tip  1  is in a rising position, and  FIG. 5B  shows a case that the coil spring  2  is compressed and deformed and thus the pin tip  1  is in a falling position. 
         [0037]      FIGS. 6A and 6B  show a pin tip attachment structure according to a fourth embodiment of the invention. While a basic structure is same as in the case of the first embodiment, the structure is different in that a bush  19  to be fitted into the hole of the pin tip  1  is configured to have only the bush part without the collar part. Here, the upper end of the coil spring  2  directly contacts to the lower end of the pin tip  1  to support the pin tip  1 .  FIG. 6A  shows a case that the coil spring  2  is stretched and thus the pin tip  1  is in a rising position, and  FIG. 6B  shows a case that the coil spring  2  is compressed and deformed and thus the pin tip  1  is in a falling position. 
         [0038]    As shown in  FIGS. 7A to 7C , the pin  3  can be attached with a sleeve configured by a separated component, without having the large diameter portion  8  (refer to  FIG. 2A ) integrally formed at the front-end portion. That is, as shown in  FIG. 7A , the large diameter portion is not integrally formed at the front end of the pin, and a small diameter portion  7  extending to the front end is formed; and the coil spring  2  is set on the ring plate  5  attached to a lower side of the small diameter portion  7 , and the bush with collar  4  is set on the coil spring  2  ( FIG. 7B ); then the bush with collar  4  is pushed down to compress and deform the coil spring  2 , so that a sleeve  15  is pressed and fitted with the front end of the small diameter portion  7  ( FIG. 7C ). Here, the outer diameter of the sleeve  15  is made to be same as outer diameter of the large diameter portion  8 , so that the upper end  13  of the bush with collar  4  contacts to a lower end of the sleeve  15  for retention. By using such a configuration, the bush with collar  4  need not have the slit groove. 
         [0039]    It is obvious that the outer diameter of the sleeve  15  need not be made to be same as the outer diameter of the large diameter portion  8 , and can be larger than the inner diameter “d” of the hole  12  of the bush with collar  4 . The bush with collar  4 , which is configured in a way of being not disengaged from the pin by press fitting of the sleeve  15  in this way, is then attached with the pin tip  1 , resulting in the same configuration as in the first embodiment. Alternatively, a nut may be screwed with the pin instead of the sleeve  15 . That is, when a screw thread portion is formed in the front end of the small diameter portion  7 , and the nut is screwed with the screw thread portion, the bush with collar  4  contacts to the nut and thus not disengaged. 
         [0040]      FIG. 8A  shows a case that one aluminum can  16  is seized to a pin tip  1   a,  and  FIG. 8B  shows a case that one aluminum bottle  17  is seized to a pin tip  1   b.  The pin tip attachment structure of an embodiment of the invention can be used for conveying a container in a shape having a small port such as the aluminum bottle  17  shown in  FIG. 8B , since the structure is configured to be usable even in the case that the pin tip  1  has a small diameter. However, the pin tip  1   a  having a large diameter as shown in  FIG. 8A  can be obviously attached by using the same structure.