Abstract:
A controller in a banding packing machine which can easily correct a shift from the predetermined timing cycle. The controller includes a cam shaft having a plurality of cams, a timing plate which includes a plurality of holes corresponding to rotation positions of the cam shaft, and a detecting means. An inching mode is also disclosed which provides for the manual adjustment of presser members following a step in the rotation of the cam shaft.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a banding packing machine and more particularly to a controller in a banding packing machine which controls cutting, welding and the like for binding a band in a predetermined timed cycle. 
     2. Description of the Prior Art 
     In an automatic or semi-automatic banding packing machine, a band led from a band reel is wound upon an object to be packed and is then clamped, and subsequently, is returned to the band feeding side and is tightened. Then, a bound portion of the band is melted by a heater almost simultaneously with the cutting and is then bonded by means of a press. These operations are carried out continuously and instantaneously in one cycle. 
     In such a banding packing machine, a control portion utilizing a cam is provided to precisely carry out the operations. The control portion controls the timing of the operations of the band packing machine. More specifically, a plurality of cams are provided on one cam shaft of the control portion. When the cams are rotated with the cam shaft, cam followers corresponding to the cams are moved vertically so that a plurality of members carry out their predetermined operations, such as clamping, return, tightening and the like. 
     When a large number of operations are to be thus carried out continuously in a short time period, the band is insufficiently gripped and the band cannot be sufficiently returned if member positions become shifted during the operation of the cam and the cam follower, or during the operation of a roller and a touch roller. 
     When an operation failure occurs in any of these operations in a conventional banding packing machine, it is necessary to stop all driving operations at once. The cam shaft must then be manually rotated to perform a banding operation. Specifically, in order to determine whether or not related members are set in their proper positions, the cam shaft must be rotated to each of its original position, a reverse rotation start position, a tightening start position, a normal rotation start position and the like on the cam shaft. 
     However, it is time and labor intensive to manually rotate the cam to each position and confirm an accurate positional relationship. Furthermore, it is difficult to decide whether or not a stop position is reached after the manual rotation is in a normal position. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present invention to provide a controller in a banding packing machine which can regulate an operation distance by a link operation, and can easily correct a shift from the predetermined, correct timed cycle. 
     In order to attain this object, the present invention provides a controller in a banding packing machine, comprising: 
     a cam shaft which is rotated upon receipt of force from a driving source; 
     a plurality of cams provided on the cam shaft; 
     a timing plate provided on the cam shaft, said timing plate having a hole formed thereon which corresponds to a predetermined position so that a rotation position of the cam shaft can be detected; and 
     a detecting means for detecting that the hole formed on the timing plate has reached the predetermined position, and 
     an inching mode which stops the rotation of the cam shaft when the detecting means detects the hole formed on the timing plate. 
     With such a structure, it is possible to ascertain whether or not a related member is in its proper predetermined position by setting the inching mode to occur when the hole formed on the timing plate reaches a predetermined position. In the case when the related member does not have a predetermined positional relationship, it is preferable that the power source be turned off a single time to regulate the position. 
     It is preferable that the following two modes be switchable: (1) the inching mode for stopping the rotation of the cam shaft when the detecting means detects the hole of the timing plate; and (2) the operation mode for causing the detecting means to detect the hole of the timing plate, thereby driving the cam shaft in a normal cycle. 
     If the inching mode and the operation mode can be thus switched, the inching mode is set before a first operation is carried out and it is ascertained whether or not the inching mode is set in the normal condition. If the inching mode is set in the normal condition, the operation mode may be exactly set to carry out a continuous operation. On the other hand, if the positional relationship is not accurate, it is preferable that the position regulation be performed again and the operation mode then be set. 
     As described above, when the inching mode is set, the controller in the banding packing machine in accordance with the present invention makes it possible to determine, at each time, whether or not the positional relationship of each member is set in a correct position. 
     Accordingly, it is possible to easily adjust the positional relationship between the members. 
     These objects as well as other objects, features and advantages of the present invention will become more apparent to those skilled in the art from the following description with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view showing a control portion in a banding packing machine according to an embodiment of the present invention; 
     FIG. 2 is a front view showing a state in which the control portion according to the embodiment is assembled; 
     FIG. 3 is a perspective view showing a timing plate fixed to a cam shaft; and 
     FIG. 4 is a sectional view showing an operation for carrying out banding by means of the control portion according to the present embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention will be described below with references to the drawings. 
     FIG. 1 shows a control portion in a banding packing machine for performing an operation for clamping, welding and cutting a tip portion of a band. 
     In the control portion, a right presser member  2 , a left presser member  4  and a middle presser member  6 , which are vertically moved by the operation of a cam mechanism, are accommodated in a support block  8 , and the support block  8  is supported between a pair of fixed plates  12  and  14  through a screw member  10  or the like. 
     As shown in FIG. 2, a cam shaft  22  is rotatably supported on shaft insertion holes  11  and  13  formed on the fixed plates  12  and  14 . The cam shaft  22  is rotated upon receipt of the force of a driving source such as a motor which is not shown. Cam followers  16 ,  18  and  20  are attached to the lower parts of the right presser member  2 , the left presser member  4  and the middle presser member  6 , respectively. In addition, these cam followers  16 ,  18  and  20  abut on the peripheral surfaces of cams  24 ,  26  and  28  provided on the cam shaft  22 . The cam followers  16 ,  18  and  20  are pulled toward the cam side with spring  30  so that they are maintained in a position which abuts on the cams. A timing plate  45  is fixed integrally with the cam shaft  22 . 
     The position of the cams  24 ,  26  and  28 , and members to be operated by the cams, can be confirmed by the timing plate  45 , when the cams  24 ,  26  and  28  supported on the cam shaft  22  are rotated. For example, three holes  42 ,  44  and  46  are formed apart from each other at predetermined intervals as shown in FIG.  3 . For example, the detection of the holes  42 ,  44  and  46  indicates the start of each step. If the rotation of the cam shaft  22  is stopped when the hole  42  is detected, it is possible to identify the positional relationship between the members for the start of a next step. 
     Accordingly, if the cam shaft  22  is placed in an original position when the hole  42  is detected, for example, it is possible to ascertain whether or not the right presser member  2 , the left presser member  4  and the middle presser member  6  are set in their proper original position. 
     Accordingly, if the position is correct at that time, a signal for the original position can be output with the correct timing cycle. 
     As shown in FIG. 4, the band B is inserted into a guide hole  48  of the right presser member  2  by the driving force of a band feeding roller  50 . When the tip of the band B is passed through the band arch  51  and abuts on a stopper (not shown) by the driving force of the band feeding roller  50 , the right presser member  2  is lifted to interpose the band B between the non-slip portion  49  and the slide table  34 . 
     Thereafter, the band feeding means  50  is reversed in the directions of the arrows in FIG. 4 to pull the band B. Consequently, the band B is forcibly removed from a band guide arch  51  and is wound onto an object W to be packed. When the band B is wound onto the object W to be packed, band B is further pulled and tightened. After the band B is thus tightened, the left presser member  4  is moved to an uppermost position to interpose the binding rear end side of the band B between the non-slip portion  3  of the left presser member  4  and the slide table  34 . In this state, the binding tip portion of the band B and the binding rear end portion are opposed to each other with a space maintained vertically. A heater  36  is inserted in the space, thereby melting the surface of the band B. When the surface of the band B is molten, the middle presser member  6  is lifted to push the molten portion thereagainst and is bonded thereto. At this time, the cutting blade  40  of the middle presser member  6  cuts the band B together with the right presser member  2 . 
     Thus, a series of banding works are carried out. If the heater  36  shown in FIG. 4 is supposed to protrude from the side when the hole  44  is detected, it is necessary to adjust its location if the heater  36  is not in a protruded position when the hole  44  is detected. In the present embodiment, an inching mode is set so that the rotation of the cam shaft  22  is stopped when detecting means  50  detects the hole  44 . Therefore, it is possible to easily ascertain whether or not the heater  36  has protruded correctly. 
     In prior art banding packing machines, usually, when the power source is turned on, a normal cycle of operation occurs, which involves the clamping, return and tightening of a band, and then the pressure weld of the band through the heater, in that order. Therefore, even if the heater  36  has not protruded in its original position, the cam shaft  22  passes by the same position and is rotated differently from the present invention. In the present invention, the cam shaft  22  stops rotating every time the holes  42 ,  44  and  46  are detected. Therefore, it is possible to ascertain whether or not each member is placed in a correct position. 
     In the control portion according to the present invention the inching mode for adjusting the positional relationship between the members is provided. Therefore, it is possible to ascertain whether or not the positional relationship has deviated during the stop. 
     In the proper condition, moreover, it is preferable that the operation mode should be exactly set to carry out a continuous operation. 
     Furthermore, if the inching mode and the operation mode can be thus switched, the operation mode can be set to immediately operate the banding packing machine when it is in a correct position. Therefore, deterioration in productivity can be prevented. 
     While the preferred embodiment of the present invention has been described above, the present invention is not restricted to the embodiment. 
     For example, while three holes are formed on the timing plate in the preferred embodiment, any number of holes may be provided. Furthermore, the number of the cams provided in the cam shaft  22  is not restricted to three. Additionally, switching from the operation mode to the inching mode may be carried out by turning on a power switch while pressing a reset switch. Moreover, the reset switch is not restricted; but another switch may be used. In the inching mode, furthermore, the operation may be stopped in each timing and the reset switch may be pressed to proceed to a next step. 
     Numerous modifications and alternative embodiments of the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only, and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and/or function may be varied substantially without departing from the spirit of the invention and all modifications which come within the scope of the appended claims are reserved.