Bottle gripper
This invention relates to a bottle gripper to be used to grip the head of a bottle when the bottle is being electrostatically coated with powder. 
     It often happens that glass bottles of soft drinks such as cola, cider, and others such as beer, are broken by pressure inside the bottle caused by sunshine. To avoid this, the outer surface of the bottle is covered with a synthetic resin. One proposed method of achieving this is to make an electrostatic coating with a synthetic resin powder over the outer surface of the bottle and then to apply heat to form a solid film. For this use, some new resin powders have been produced. However, in the process of powder coating the bottle, there arises a serious problem because there is difficulty in containing with a cap the substance in the bottle if any synthetic resin powder, even a trivial amount, attaches to the head of the bottle. It is absolutely necessary in powder coating to obtain means for avoiding attachment of resin particles to the head of the bottle. 
     Also, it is required to form a clearly defined coating boundary at the upper end of the coated film formed on the bottle head to give the film longer life and to maintain the commercial value of the bottle. 
     To achieve the aforementioned requirements, some apparatus for avoiding the attachment of resin powder particles to the head of the bottle have been proposed with means for blowing or suctioning gas or a combination of these. However to insure a long period of operation and to form a clear boundary, further development of new reliable means is urgently desired. 
     One object of the present invention is to solve the above problems and to furnish a gripper for bottles that is capable of completely avoiding the attachment of resin to the bottle head while holding it firmly in the process of resin coating and establishing the formation of a clear boundary at the upper end of the coating. 
     Another object of the present invention is to furnish a bottle gripper that ensures against penetration of powder thereinto. 
     A further object of the present invention is to furnish a bottle gripper that enables easy removal of resin particles from the gripper after electrostatic coating has been finished. 
     The bottle gripper of the present invention is constructed using a cylindrically shaped arm, an inwardly projecting supporter and a resilient cap. Such a cap is formed of an outer cylinder and an inner cylinder extending from the lower end of the outer cylinder providing a gap therebetween and a flat wall formed on the top of the inner cylinder. A shaft is inserted with a loose fit in the center of said cylindrically shaped arm. From the lower end of this shaft plural branch plates extend to which swingable pieces are mounted for engagement by said supporter. Skirt portions of the swingable pieces are inserted in the gap formed between said outer cylinder and inner cylinder. 
    
    
     Other features and objects of the invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawings in which: 
     FIG. 1 is a front view of a cross section of a bottle gripper of the present invention when its resilient cap is closed. 
     FIG. 2 is a cross section view taken along the line II--II in FIG. 1. 
     FIG. 3 is a front view of a cross section of the bottle gripper of the present invention when the resilient cap is opened. 
     FIG. 4 is a front view of a cross section of the resilient cap of the present invention. 
     FIG. 5 is a cross section view taken along the line V--V in FIG. 4. 
     FIG. 6 is a plan view of a swingable piece of the present invention. 
     FIG. 7 is a front view of a cross section of the swingable piece. 
     FIG. 8 is a side view of the swingable piece. 
     FIG. 9 is a front view of a cross section of a resilient cap of another embodiment. 
     FIG. 10 is a front view of a cross section of another embodiment of the present invention. 
    
    
     Now reference is made to accompanying drawings. 
     In FIGS. 1 and 2, numeral 1 designates a cylindrical arm in which a shaft 2 is inserted with a loose fit. At the lower portion of the cylindrical arm 1, the upper part of a supporter 3 is screwed with its lower end projecting inwardly. Further, at the lower portion of cylindrical arm 1, a resilient cap 4 is engaged and secured with screw by an outside holder ring 5. Also the lower portion of the shaft 2 has branch plates to which the heads of a plurality of swingable pieces 7 are attached with pins 8. 
     As seen in FIGS. 4, 5 and 9, resilient cap 4 is formed of a pair of cylindrical walls including an outer cylinder 9 and inner cylinder 10 extending integrally from the lower end of outer cylinder 9 with a plurality of connections 19 between the upper end of inner cylinder 10 and outer cylinder 9 so that a generally annular gap 20 is formed between these cylinders. An upper flat wall 11 is formed at the upper end of the inner cylinder 10 and an annular ridge 12 is formed at the inner periphery of the lower end of the inner cylinder 10. If necessary, such ridge 12 is provided at the middle part of the inner wall of the cylinder 10. 
     As shown in FIGS. 6-8, each swingable piece 7 has at its upper end pin holes 13 to receive pin 8 and a projection 14 to be engaged with said supporter 3. The lower portion of the swingable piece 7 forms a skirt 15 dividing the circumference into four equal sections. However, the skirt is not always required to be sized as just one fourth of the circumference. A groove 16 is formed in this skirt 15 to receive said connection 19 as necessitated. 
     Operation of this bottle gripper is as follows. In FIG. 3, first, skirt 15 of swingable piece 7 is inserted in the gap between outer cylinder 9 and inner cylinder 10 of cap 4. Then the upper portion of cylindrical arm 1 is connected to a chain or conveyor (not shown) and advanced in one direction. As shaft 2 is pushed in the direction of arrow A2 by turning of a cam plate or screw (not shown), projection 14 of swingable piece 7 is supported by supporter 3 and swingable piece 7 is turned with pin 8 as its center in the direction of arrow A7 to open wide the lower portion of resilient cap 4 (FIG. 3). 
     When the head of a bottle 17 enters inside of resilient cap 4, shaft 2 is pushed by the cam plate in the direction reverse to arrow A2 as in FIG. 1 whereby projection 14 is disengaged from supporter 3, swingable pieces 7 are pressed by supporter 3, and resilient cap 4 comes to grip the head of bottle 17 with its spring action. In this instance, ridge portion 12 of cap 4 engages the portion just below a rib 18 of the bottle head 17 to securely grip it whereby powder and any other matter can not enter inside the gripper. 
     While bottle 17 is securely gripped by resilient cap 4 as shown in FIG. 1, electrostatic coating of resin powder may be made on the surface of bottle 17. As described before, when the painting or coating is over, shaft 2 is pushed to the direction of arrow A2 to the state as shown in FIG. 3, thus there is formed a clear boundary line 23 at the upper end of powder layer and cap 4 can be removed from the bottle 17. 
     In the present invention, with only upward or downward movement of shaft 2, resilient cap 4 can easily grip the head of the bottle 17 very securely. Since the bottle head is covered by cap 4, any powder particle does not attach to the head of the bottle. Even when the bottle is not yet gripped by the gripper with a number of chains connected thereto, powder particles will not deposit on the swingable pieces as such swingable pieces 7 are completely enclosed by outer cylinder 9, inner cylinder 10 and upper flat wall 11. Therefore there will not occur any trouble caused by clogging of resin powder. 
     Another embodiment is illustrated in FIG. 10. Therein at the lower end of a cylindrical arm 1, a supporter 3 is integrally formed and at the outer periphery of the supporter 3, a resilient cap 4 is engagedly mounted. A cylinder 21 is attached to the lower end of a shaft 2. Branch plates 6 project downwardly from the cylinder 21 to which swingable pieces 7 are pivotally attached with pins 8. Projections 14 of the swingable pieces 7 are to be engaged in a recess 22 of the supporter 3. Other components of this embodiment are the same as those in the embodiment in FIG. 1.