THE INDIA RUBBER WORLD 



New Machines and Appliances. 



SAND-BLASTING BASES FOR SOLID TIRES. 



SAND-BLASTING the steel bases of solid tires is now an 

 accepted practice in ihe manufacture of tires of the solid 

 type, as a perfectly clean base is essential for satisfactory 

 results. This object is obtained in an efficient manner by the 

 sand-blasting process here described. Moreover, the result is a 

 pitted, roughened surface to which the hard-rubber compound 

 adheres with greater tenacity. 



The various sizes of tire bases have necessitated the design of 

 two distinct types of apparatus. For the smaller bases, up to 

 eight inches wide by 24 inches in diameter, a cabinet is used into 

 which the bases are placed by hand, through a front door. The 

 bases, mounted on a spindle, revolve under sand-blast guns at a 

 circumferential speed that insures the surfaces being uniformly 

 and thoroughly cleaned. The various widths are taken care of 

 by the use of four sand-blast guns w^hich can be operated inde- 

 pendently. On the outside of the cabinet opposite the door is 

 the driving mechanism for revolving the spindle at the proper 

 speed, consisting of tight-and-loose pulley and the necessary re- 

 duction gears. A quick-acting air-valve is within easy reach 

 of the operator for turning the air supply on and off. Individual 

 valves for each sand-blast gun serve the purpose of shutting 

 off those guns which are not required for the narrower bases. 



A larger cabinet and different procedure is required for bases 

 up to 14 inches wide by 48 inches in diameter. The bases are 

 mounted on an inclined runway, held in an upright position by 

 guide rails, and delivered to the charging side of the cabinet. 

 They are automatically introduced into the cabinet one at a time, 

 and are revolved by rolls. Seven sand-blast guns are mounted in 

 the top of the cabinet, adjustable to the various diameters and 

 width by hand wheels on the outside of the cabinet. When a 

 base is cleaned the operator trips the mechanism which discharges 

 the cleaned base onto a second inclined runway, and automati- 

 cally takes on another base to be cleaned. The charging, revolv- 

 ing, and discharging operations are entirely automatic except for 

 the timing of the clean, which necessarily is in proportion to the 

 diameter of the bases, and therefore must be determined by the 

 operator. 



The sand-blast guns used on both cabinets are of standard de- 

 sign as used in connection with other types of similar apparatus. 

 They are of the induction type, which means that the sand is ele- 

 vated from a hopper beneath the cabinet to the gun by syphoning 

 action of the air jet. Each gun consumes approximately 67 cubic 

 feet of free air per minute at a most advantageous pressure of 

 60 pounds per square inch. The abrasive used for sand-blasting 

 falls into a hopper at the bottom of the cabinet. This hopper has 

 four and seven sand-feeding devices corresponding to the number 

 of guns used on the two cabinets. These sand-feeds supply sand 

 to the guns only when the air is turned on, that is, when the gun 

 is in operation. The connection between the sand-feeds and the 

 guns consists of heavy, wire-inserted rubber hose. 

 ' As it is essential that an adequate e.xhaust and dust-collecting 

 system be used, therefore dust-arresters and exhaust-fans are 

 connected to the sand-blast cabinets by galvanized iron piping of 

 sufficient size, producing the desired results. (The W. W. Sly 

 Manufacturing Co., Cleveland, Ohio.) 



SHERARDIZING POLES AND MOLD CAVITIES. 

 From the beginning the surfaces of steel poles or mandrels 

 used in the manufacture of open heat articles, such as hose and 

 inner tubes, become corroded and pitted, especially at the ends, 

 thereby limiting their usefulness. This corrosion is due to the 

 action of steam and sulphur gases on the exposed surfaces of 

 the mandrels during the process of manufacture. Sherardizing, 



however, eliminates this difficulty and consequently has become 

 a standard practice with regard to inner tubes and mandrels. 

 There is no reason why the process of sherardizing should not 

 be applied with success to hose poles in general. This process 

 will also be found advantageous as a permanent lustrous coating 

 for mold cavities in the manufacture of hot-water bottles, bulbs, 

 balls, toys, and similar molded goods. 



Sherardizing or dry galvanizing is a process of metallic sub- 

 limation applied by first grinding and polishing steel articles 

 which are then packed in a container, with zinc dust, and 

 subjected to heat. As the result, a deposit of zinc is formed that 

 not only coats the steel surfaces but penetrates them and pre- 

 sents a hard, smooth surface of a silvery color that resists rust 

 and will not peel. The deposit does not alter the dimensions 

 of the mold since the coating is only .002 of an inch in thickness. 



It is not necessary that all articles should be ground and 

 polished as this process is applied only to mandrels which must 



<ING Tube M.\ 

 Sher.\rdizi> 



:)Kn.s Bei-ng Rolled Into 

 Furnace. 



be relieved of all holes to insure a perfectly smooth surface. 

 The standard method as applied to preparing material for 

 nickel plating will usually cover all items. 



It is recommended that a standard splicing connection be 

 adopted on hose pole mandrels and all mechanical fittings in- 

 tended to be sherardized, which would overcome any corrosions 

 in the joints. Furthermore, to extend the life of inner tube 

 mandrels or poles, plugs should be inserted in one end with a 

 hole one inch square for turning in the lathe in order to over- 

 come the ragged edges and the cutting of the mandrel so common 

 when using a grip chuck. 



Sherardizing of mandrels is essential at the present time, due 

 to the need for saving steel, as a sherardized mandrel will last 

 almost indefinitely and when worn it can be retreated and 

 restored at a minimum cost. With this fact in view manufactur- 

 ers have adopted a mandrel of no lighter than No. 13 gage on 

 the very smallest sizes, which will allow regrinding and refinish- 

 ing several times and still retain enough stock to answer general 

 requirements. (The New Haven Sherardizing Co., New Haven, 

 Connect'cut.) 



"Rubber Machinery," by Henry C. Pearson, is filled with valu- 

 able information for rubber manufacturers. Price, $6. 



