Aici-ST 1. 1914. 



THE INDIA RUBBER WORLD 



615 



New Machines and Appliances. 



DIES FOR PRESSED RUBBER COMBS. 



WHEN hard rubber stock in a plastic condition is pressed 

 between comb forming dies of the usual construction, it 

 is impossible to force by pressure from between the dies 

 all of the material not required in the comb. This is one of the 

 reasons why so few rubber combs have been formed entirely by 

 stamping out in dies, with the comb teeth completely formed by 

 a single operation. 



Fig. 1. \\'iei.,\.nd's H.\ri) Rubber Co.mb Dies. 



In an invention of F. W'ielaiid'.s, the stock is pressed between 

 dies arranged to form a comli blank, in which all of the teeth arc 

 practically of the desired linal shape and size. The superfluous 

 stock that remains between the teeth and at the ends and sides is 

 connected to the comb by thin webs which are easily broken away. 

 Reference to the accompanying drawings in 

 connection with the following description will 

 give an idea of the construction of these dies 

 and the manner in which the comb is formed. 



In I'"ig. 1, A is a plan view of the lower 

 half of the die and B is a partial cross section 

 and part exterior view of the upper and lower 

 halves. C shows the shape of the rubber blank 

 after it has been pressed and removed from 

 the dies and D is a cross section of the same 

 blank. The dies are formed so that when the 

 two halves are placed together, spaces F are 

 <eft for the teeth. Between these spaces are 

 smaller spaces E, which receive the surplus 

 materia! pressed out from spaces F. The 

 parts of the dies which separate the spaces E 

 and F are formed with sharp edges C, so that 

 when the dies are pressed together the surplus 

 rubber in spaces E is separated from that in 

 spaces F hy a very thin web, which is after- 

 ward easily broken away. The dies are also grooved at H to 

 receive tlie excess material pressed from the ends of the comb 

 blank. 



With this die the stock to form the comb may be of much less 

 thickness an'd width than that of the finished product. The stock 

 from which the comb is formed is materially thickened and 

 spread laterally during the pressing operation, filling up spaces 



where necessary and squeezing out surplus material where not 

 needed. The surplus material squeezed from the center of the 

 stock to form the web between the backs of the combs, is 

 forced into the hollow spaces of the die to form the backs /. 

 The surplus rubber not needed for the comb teeth is forced out 

 at the edges as shown at K, and is connected with the comb 

 blank by thin webs L. The two comb blanks arranged back to 

 back are easily broken apart and the superfluous stock removed 

 by breaking off the thin wefas. The combs are then finished by 

 buffing. The drawing M shows the form of 

 the completed comb. 



Fig. 2 shows another form of mold for 

 producing twinned combs with interlocking 

 teeth, which are connected by thin webs. A 

 plan view of the lower half of the die is 

 shown at .4 while B shows a partial cross 

 section of both the upper and lower halves. 

 C is an end view of the dies, showing the 

 relative shape and size of the rubber stock D 

 before being pressed. E shows the comb 

 blank after being pressed and shows how the 

 material completely fills up the spaces to form 

 the comb back and teeth. The teeth in a 

 comb formed by this die are necessarily closer 

 together than in the die shown in Fig. 1 and 

 the cutting edges of the opposing dies are 

 necessarily sharper and deeper. When the 

 two dies are pressed together the rubber is 

 first forced longitudinally and then across the 

 dies, or along the tooth spaces toward the 

 back of the comb. 



In pressing combs with a die of this shape 

 the large end teeth F are bent out of their normal position to 

 provide a receiving space for material to form the teeth G. 

 After the combs have been separated by breaking the thin webs 

 which connect them, the end teeth F are forced by the applica- 

 tion of heat and pressure back to their normal position, after 



F"iG. 2. Dies for Formin'g Twuxned Ribber Combs. 



which the combs are ready to be finished by a buffing wheel. 



The Werner & Pfleiderer Co., Saginaw, Michigan, is making a 

 new machine, the Universal Mixing and Kneading Machine, de- 

 signed especially for use in the manufacture of chewing gum. 

 The machinery for this industry has heretofore been adapted from 

 other lines and changed to suit the different requirements. 



