Abstract:
A device for feeding wire stock of fixed length to a cutoff tool in a linear and continuous manner by means of the reciprocating motion of a wire cutting mechanism driven by an eccentric shaft being utilized to sever and sequentially feed the cutoff wire stock one at a time to a die head.

Description:
BACKGROUND OF THE INVENTION 
     A conventional blank cutoff and feeding device for heading machines is shown in FIG. 1. The upper and lower faces of a semi-circular cutoff tool 2 at the front end of a wire cutting shaft 1 are provided with a pair of spring loaded grippers 3, which, when wire stock 4 has been cut off to fixed length, hold the severed blank and transfer it to a position upon a die 7 where the first stage of the operation will be performed. The pitch between the wire cutting operation and the first stage operation is quite long, that is, the transfer distance is rather long. Therefore, errors will occur frequently during the operation. Furthermore, the wire cutting and the transferring work for cutoff stocks usually can not be coordinated with the processing time for impacting the head of the wire stock into the desired shape. Thus, the efficiency of the heading machine is greatly reduced. 
     In addition, the roller 8 is pivotedly connected in a body with the vertical lower end of the wire cutting shaft 1 and at the same time, the roller 8 protrudes into a guide groove 9 of a sliding plate 5 under the wire cutting shaft 1 and slides reciprocally in a direction which is at right angles in respect with the wire cutting shaft 1. When the sliding plate 5 starts its reciprocating motion by means of the driving of a crank plate via a connecting rod 6, the roller 8 which is secured in a body with the wire cutting shaft 1 causes the wire cutting shaft 1 to move back and forth to accomplish the purpose of cutting wire stock to a fixed length and transferring the cutoff blank. It is quite evident that the mechanism used in the prior art has the deficiency of complexity and inaccuracy, together with fast wearing of the associated parts during operation. Consequently, it is very difficult to attain the proper operations in each stage, such as cutting, feeding and upsetting in a regular sequence of timing, so as to reduce the possibility of obtaining a high efficiency in a heading operation. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a cutoff blank feeding device used for a rotary type of high-speed cold heading machine and, more particularly, to a cutoff blank feeding device of a heading machine for screws whose body and head are substantially different in size and somewhat complex in their forms. The heading machine herein referred to is capable of forming rivets, tubular rivets, socket-head screws, hexagon-head screws, wood screws and bolts therefor, machine screws, automobile bolts, tapping screws, and screws having cross recess style roundhead, counter-sunk heads, oval heads, square heads and the like. 
     The principal object of the present invention is to provide an improvement to overcome the defects mentioned above and to provide a device in which, after the wire stock is cut off, a cutting tool is utilized for the push and feed of the cutoff blank forward in a linear and continuous way to a blank stacker and also render the foremost blank properly in alignment with the center of the die opening. Since the stroke of the wire cutting shaft only measures approximately one centimeter, and the wire cutting tool is driven by an eccentric shaft, it is not only possible to obtain a very accurate operation and a good coordination of the respective cutting, conveying and heading processing time, but also possible to accomplish an extremely high-speed and stable heading operation. 
     A further object of the present invention is to provide a cutoff blank feeding device having a simplified construction, which produces no malfunctions, long life and having a high product quality when used in a rotary type of highspeed cold heading machine. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1A depicts a front view partially in cross-section of the conventional blank cutoff and feeding device for a heading machine; 
     FIG. 1B depicts a plan view of the sliding plate of FIG. 1A; 
     FIG. 2 depicts a plan view partially in cross-section of a rotary type of high-speed heading machine in which the blank cutoff and feeding device of the present invention is used; 
     FIG. 3 depicts a cross-sectional view taken along line D--D of FIG. 2; 
     FIG. 4A depicts an enlarged detailed plan view partially in cross-section of the blank cutoff and feeding device of the present invention and; 
     FIG. 4B depicts a side view of the device as shown in FIG. 4A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the figures the primary source of driving force is the main eccentric shaft 20 driven by its V-belt pulley 13 through a V-belt pulley 11 a motor 10 via the V-belt 12. A bevel gear 21 and a spur gear 22 are keyed on the main eccentric shaft 20. A main sliding block 30 having a punching means (not shown) is driven by a connecting member 31 which is pivotedly fixed to the other end 20&#39; of the main eccentric shaft 20 for performing a back and forth motion of the punching means. The bevel gear 21 on the main eccentric shaft 20 is engaged with a bevel gear 41 on a shaft 40 to drive the wire-cutting eccentric shaft 40. A connecting member 42, through which is pivotedly fixed a reciprocating wire-cutting shaft 50, is also mounted on the shaft 40. A generally U-shaped cutting tool 51 is fixed to the end of the shaft 50. An eccentric disc 43 is mounted at the further end of the eccentric shaft 40 by means a fixing key. One end of a connecting rod 44 is pivotedly connected to the eccentric disc 43. The other end of the connecting rod 44 includes a frictional connecting rod 61 having a friction plate which is positioned at the interior of a rotary die head 60. The rotary die head 60 is actuated through the connecting rod 44 and its accessories. A knockout mechanism 82 and rollers 92 are provided for feeding wire stock 90 into a die head through a straightener 91. 
     According to the present invention, FIG. 3 represents an enlarged cross-sectional view from the line D--D in FIG. 2. FIG. 4 is a partial cross-sectional view of the blank cutoff and feeding device. After the wire stock 90 is fed in through the straightener 92 and is passed through a cutting die 93, the stock 90 contacts a stopper 101 provided at the rear side of the cutoff blank stacker 100 relative to the forward direction of the wire stock for adjusting the desired length of a cutoff blank 90A. As the wire cutting shaft 50 moves forward and cuts off the fed wire stock into a pre-determined length by means of the U-shaped semi-circular cutting tool 51 fitted at the front end thereof, the two protruding arms 511 and 512 on the U-shaped semi-circular cutting tool 51 are then holding and pushing the two ends of a cutoff blank 90B forward in a parallel and accurate way into the cutoff blank stacker 100 with a uniform and equal force. 
     A retaining arm 103 having its lower foremost pointed end 104 formed with inner and outer inclined surfaces 105 and 106, respectively is provided at the upper part of the cutoff blank stacker 100 with a pivot 102 mounted above the said stacker 100 as its fulcrum. The arm 103 is able to move up and down for retaining and holding the cutoff blanks 90B tightly within the stacker 100 so as to make the cutoff blanks 90B closely stacked one by one in a linear arrangement and to position the center line of the foremost cutoff blank 90C on the stacker 100 properly in alignment with a die opening 701 of the rotary die head 60. A ram rod of the main sliding block 30 then pushes the foremost cutoff blank 90C into the die opening 701. In practice, only a moving distance of approximately 1 centimeter is sufficiently enough for the wire cutting shaft 50 to accomplish the heading work. Also, the coordination of the timing of wire cutting, feeding and heading work stages in regular sequence is very easily to be obtained, and its simplified construction and accurate operation do not call for highly skilled operators in order to obtain speedy and stable heading production.