Patent GB-422829-A (GB)
Title: Improvements in or relating to the manufacture of hollow perforated rolls
IPC: B26F1/26
Filed: 1933-07-18
Abstract: 422,829. Drilling-machines. BELOIT IRON WORKS, 815, 2nd Street, Beloit, Wisconsin, U.S.A.-(Assignees of Berry, E. E.) July 18, 1933, No. 15827/34. Convention date, Nov. 25, 1932. Divided out of 422,959 under which a Specification was laid open to inspection under Sect. 91 of the Acts, Jan. 31, 1934. [Classes 83 (ii) and 83 (iii)] [See also Group VIII] In a method of making hollow perforated rolls with a covering of rubber, such as the suction press rollers of paper making machines, a metal shell has a number of holes drilled therein by a multiple-spindle drilling machine using an indexing mechanism for the work, the shell is then removed from the machine to be supplied with the rubber covering, after which it is replaced in the drilling machine and has the rubber covering perforated in correspondence with the shell perforations by effecting the same indexing operations as are used for drilling the shell. A roll consists of a metal shell 10 and a rubber covering 11 and preferably is of the type described in Specification 422,959, wherein the outer portion 11<a> of the rubber is soft and the inner portion 11<b> is harder. The shell 10, which is preferably a centrifugal bronze casting, is turned smooth and may be polished slightly oversize and is then placed in a drilling machine whereby a longitudinal series of holes 12 is drilled by a gang of drills 19, Fig. 2. On indexing the work by means of mechanism 20, the gang of drills is displaced axially so that each drill will form a helical series of holes of small pitch compared with the distance between the holes. During drilling the work is cooled by impinging streams of air, and the truth of the holes drilled is tested by means of a gauge inserted in the holes and having laterally extending arms contacting with the work on opposite sides of the holes. After drilling, the end hole next to the indexing mechanism 20 in the first row drilled, is broached square or rectangular as shown at 22, Fig. 3, the shell is finished to size, annular or helical threads are turned on the outer surface, dove-tailed slots 10<a> are planed therein, burrs are removed from the inner ends of the radial holes 12, and the holes necessary for attaching the roll heads to the shell are drilled and tapped. The rubber covering is then applied and cured, a small hole is drilled through the covering from the inside in line with the centre of the broached hole 22 and similar holes may also be drilled in line with all the holes of the first row. The covered shell is then replaced in the drilling machine in the same position relatively to the indexing mechanism, and adjusted so that the drills 19 register with the small holes in the covering. Trial holes are drilled through the rubber by a smaller number of drills than the complete gang 19, and if these register exactly with the holes in the metal shell the latter is moved to its original indexing position and the holes are produced in the rubber covering by performing the same indexing motions as were used for drilling the metal shell. Cold water is used to cool the drills and remove cuttings. In applying the covering, some of the rubber penetrates the holes 12, as shown in Fig. 7, and since the holes in the rubber are smaller in diameter than those in the shell, rubber plugs 10<b> united to the covering 11 by thin walls are left by the drilling operation. These plugs are removed by punches 28 inserted in the drill-spindles which are not rotated but are fed down by the feed mechanism of the machine. The punches are long enough to penetrate to the interior of the roll and are guided by a perforated plate 27. The roll is finally removed from the drilling machine and mounted on endless bands supported on rollers so that it may be cleaned and inspected and any plugs which have not been removed by the punches 28 may be punched out by hand.