US2766512A - Method for the production of ballbearing races and similar parts - Google Patents

Description

Oct. 16, 1956 HATEBUR 2,766,512

METHOD FOR THE PRODUCTION OF BALL-BEARING RACES AND SIMILAR PARTS Filed June 8, 1953 5 Sheets-Sheet l Oct. 16, 1956 F. B. HATEBUR METHOD FOR THE PRODUCTION OF BALL-BEARING RACES AND SIMILAR PARTS 3 Sheets-Sheet 2 Filed June 8, 1955 ilv. x I

m-lum mllllllll Oct. 16, 1956 F. B. HATEBUR METHOD FOR THE PRODUCTION OF BALL-BEARING RACES AND SIMILAR PARTS 3 Sheets-Sheet 5 Filed June 8, 1953 w a V WIII Illilil ll il 2/ mmimmun United States Patent METHOD FOR THE PRODUCTION OF BALL- BEARHNG RACES AND SIMILAR PARTS Friedrich Bernhard Hatebur, Basel, Switzerland Application June 8, 1953, Serial No. 359,980

Claims priority, application Germany June 9, 1952 3 Claims. (Cl. 29-1484) This invention relates to a method for the production of ball-bearing races and similar parts.

Ball-bearing races were hitherto made either from solid material by machining, from rod material by upsetting combined with the pressing back into the rod the bunch of material displaced from the hole on forging machines, from tubes, from flat bars by hot stamping, or, in the case of races of large dimensions, from rough forgings. When making small races from the solid there is a high percentage of chip waste. When the races are made by upsetting on forging machines the liquated core zone of the rod material is forced back into the rod by spreading during the displacement in the punching operation and at the next following upsetting operation into the material of the next race, with the result that unfavorable properties are imparted to the running surface. To make the races from tubes requires expensive raw material and is therefore uneconomical.

The object of the invention is to produce in massproduction small to medium sized ball-bearing races with good flow lines and to obtain the necessary roller bearing characteristics almost without waste and with high output figures.

To attain this object a semi-finished or intermediate workpiece is, according to the invention formed by pressing in the shape of two partly telescoped but at first cohering concentric parts, the inner part preferably having countersunk holes on both sides; this workpiece is subsequently divided into two separate concentric parts of different diameters with possibly a small piece of waste from the core hole of the inner part.

It is advisable to produce the workpiece or blank by the plastic deformation of a cylindrical plate which in turn is pressed from a length of rod in known manner. The cohering concentric parts of the blank can be separated and the hole punched in the inner part in a single stamping operation.

The method is preferably carried out in a continuous operation consisting in cutting off a length from an inductively heated rod of section material, pressing this length under heat to form a cylindrical plate in successive stages, forming therefrom an intermediate workpiece or blank in the shape of two two partly telescoped but cohering concentric parts, and finally in a single operation separating the concentric parts and perforating the inner part, after which the finished parts of different diameters are calibrated by calibrating devices.

This method can be carried out on cross-feed presses, the hot rolling devices of which are coupled at the delivery point for calibrating the workpieces as they drop out. It is possible by suitably forming the pressing dies in the manner hereinafter described, to eject at each working stroke of the hot press two rings of diiferent diameters within the prescribed tolerance limits, which are calibrat ed by subsequent rolling, so that the rings, after the hardening process, need only be ground.

The invention is illustrated by way of example in the accompanying drawings in which:

Fig. 1 is a diagrammatic top plan view of a cross-feed press for carrying out the method according to the invention,

Fig. 2 is a diagrammatic longitudinal section of the press shown in Fig. 1,

Fig. 2a shows in front elevation the tongs serving to grip, hold and feed the workpiece,

Fig. 2b shows a cross-sectional view along the line 11b through Fig. 2,

Fig. 3 is a diagrammatic longitudinal section of the press similar to that shown in Fig. 2 but at the end of the cross movement of the feeding elements,

Fig. 4 is an enlarged cross-sectional view of a workpiece.

As raw material for carrying out the method the usual ball-bearing steel in rod form is chosen, its diameter being determined by the final dimensions of the race. The material is preferably soft annealed to avoid cementite network. The structure of the spheroidal perlite thus obtained is maintained during the hot deformation.

The rod, as can be seen in Fig. 1 is heated to forging temperature by a medium frequency induction heating device 2 which enables an extremely short heating period and consequently a constant structure to be obtained, so that the hot pressing can take place at temperatures between 950 and 850 C.

The heated rod 1 is held in a two-piece clamping tool chuck 3 (Fig. 2) and length of the current volume is cut off by the lateral movement of the carriage 5 carrying the parting tool in the direction of the arrow at. The length 4 held by the claw 7 on the parting tool 6 is then carried to the first pressing matrix 8 by the lateral movement of the carriage 5 (Fig. 3).

The pressing matrix 8 and the following matrices are in alignment and their axes are parallel to that of the chuck 3. The die carriage 10 with the dies coordinated to the individual matrices mounted therein, moves vertically to the matrix housing 9 in the direction of the arrow [2. The elements efiecting the forward and return movements of the die carriage 10 relative to the matrix housing 9 on the one hand and the lateral movement of the workpieces from matrix to matrix on the other hand are in themselves known so that a detailed description thereof is not necessary.

As soon as the rod length 4 has reached the position shown in Fig. 3 in front of the pressing matrix 8, the die carriage 10 moves in the direction of the arrow Z2 towards the matrix housing 9 so that the feeler die 12 resiliently mounted in the pressing die 11, presses the length 4 out of the parting tool 6 and into the matrix 8 where, after the lateral return movement of the parting tool 6, it is pressed to form a plate 13 by the die 11.

The plate 13 is then pressed out of the matrix 8 by the controlled ejector pin 14 and the axially movable bottom plate 15 of the matrix. The tong halves 16 and 17 (Figs. 1 and 2a) in operative connection (not shown) with the carriage 10 grip the plate 13 as it slips out of the matrix 8 and carry it automatically in front of the second presing matrix 18. As the die carriage 18 again moves forward, the die 19 cooperating with matrix pushes with the aid of the die sleeves 20 and 21 the plate 13 out of the tong halves 16 and 17, which in the meantimehave travelled laterally to the second pressing position, and into the matrix 18. As the carriage continues its forward movement the tong halves 16 and 17 return immediately to the first pressing position (matrix 8) and are ready to receive another plate 13.

A disk 25 is now formed from the plate 13 by the die 19 and the sleeves 20 and 21 on the one hand and the matrix 18, matrix sleeve 23 and rigid matrix bottom die 24.

The plate 13 is moulded by a plastic deformation process in such a manner that two interconnected tclescoped annular bodies 25 and 25 are formed, the inner body or ring 25" having on each side countersunk holes 26, 26 preferably of different depths (Fig. 4). This pressing operation produces the blank for a pair of ball-bearing races which, owing to their peculiar twin birth correspond exactly in their structural character on the one hand, and on the other hand produce a very small quantity of waste in the subsequent pressing operation.

During the return movement of the die carriage 10, the annular body 25 is pressed by the controlled ejector pins 27 and 28 out of the matrix 18 over the die sleeve 24 and gripped by the guided pair of tong arms 2? and 30. This pair of tonk arms 29 and 30 moves laterally to the third pressing position in front of the matrix 31 (Fig. 3) during the continued return movement and at the beginning of the next forward movement of the die carriage it). As the carriage continues its forward movement the hollow die 32 presses the annular body 25 into the matrix 31. The outer ring 25 of the annular body then bears with its end face against the matrix sleeve 33 so that the wall w (Fig. 4) between the outer ring 25' and the inner ring 25" is sheared through by the advancing hollow die 32 (shown in Fig. 2) and the smaller inner ring 25" is completely separated from the larger outer ring 25'. At the same time the smaller inner ring 25 is pressed by the hollow die 32 against the matrix sleeve 32 and the stationary matrix located therein, with the result that the waste piece of plate 37 is punched out. The inner bore of the hollow die 32 serves as a punch. The waste pieces 3'7 are ejected thru the aperture 38 of the hollow die 32 when the die carriage 10 is in its rearward position and pass outwards along the guide channels 4-6 (Fig. 1).

When separating the annular body 25 into two rings 25 and 25 and when stamping out the waste disc or plate scrap 35, the inclined end faces of the annular body are vertical to the axis of the matrix 31 so that, after the separation all the end faces of the individual rings are vertical to the axis of the hole in the rings.

The separated rings 25 and 25" are then ejected from the matrix 31 preferably in the following manner:- The ejector die 4? thru the intermediary of the ejector 50 and the three inner ejector pins 55 arranged around its periphery at an angle of 120 apart and pressing onthe inner matrix sleeve, first press the smaller ring 25 in the matrix sleeve 33 only so far that this ring 25" cannot again enter the ring 25'. As the ejector die 49 continues to advance both rings 25 and 25" are pushed forward by the spring 51, the spring loaded sleeve 53 and the three outer ejector pins 52 likewise mutually distributed at an angle of 120 apart around the periphery of the sleeve 53, until the larger ring 25 in front of the matrix 31 can be stripped off by the feeler lever 41 (Fig. 1). The arrangement of the two sets of three ejector pins 55 and 52 is illustrated in section A-B (Fig. 2). In the last mentioned position the spring loaded sleeve 53 supporting the spring 51 bears against the rear bearing 54 so that as the ejector die 49 continues to move forward the spring 51 is compressed. The central ejector 50 thru the intermediary of the three ejector pins 55 and the matrix sleeve then pushes the smaller ring 25" so far forward that this is also brought in front of the matrix 31 and in this position can bestripped olf. The finished rings :drop into a chute (not shown) which guides them into the channels 44, 45 whence they are separated according to size, pass to automatically controlled hot rolling arrangements which enable the race rings to be roll calibrated under heat according to width and internal and external diameter. As the ejection from the press in a given period of time is greater than the capacity of the rolling device, several rolling devices are preferably provided which are fed consecutively from the channels 44, 45 by suitable switches or gates.

The rolling enables narrow tolerances to be maintained in the width and internal diameter of the larger rings and also in the width and external diameter of the smaller rings, so that the rings after hardening need only to be ground.

When the rings have been rolled they pass into a continuous compensation furnace for the purpose of cooling down slowly.

The working speed of the press in the case of rings with maximum external diameters up to 50 millimetres is about 60 pieces per minute, and in the case of rings of larger diameter up to millimeters, is 35 to 40 per minute.

One of the chief advantages of the method consists in the high output due to the twin pressing, so that at the above mentioned working speeds high output figures can be doubled by the ejection of the inner and outer rings. Another important advantage of the method is the reduction in the quantity of waste to only 6 to 8 percent of the weight of the two finished ball-bearing races.

It is evident that the method is not restricted to the production of ball-bearing races. Other rings can be made in the same manner to tolerances and economically. It is also possible to manufacture in pairs by this method non-circular parts fitting one within the other, and that the inner part need not necessarily be perforated.

I claim:

1. A method of producing ball-bearing races and similar parts, which includes the steps of: deforming under heat a round plate into an intermediate work piece having coaxial annular portions integral with each other and arranged one partially within the other, the inner end face of the portion with smaller outer diameter and the adjacent outer end face of the adjacent portion with larger outer diameter being inclined in the same direction with respect to the axes of said portions thereby defining a bridge between said portions, the cross section of said bridge having a thickness substantially equalling the thickness of said coaxial portions; subsequently separat ing said coaxial portions while shaping said end faces of said portions to be transverse to the axes thereof; and punching a hole through the portion with smaller outer diameter.

2. A method according to claim 1, which includes the step of: substantially simultaneously with the deformation of said plate into said intermediate work piece pro- Viding the outer end face of the portion with smaller outer diameter with a counter sunk bore to such an extent that a thin disc section remains between the bottom of said counter sunk bore and the adjacent annular portion of the portion with smaller outer diameter. 7

3. A method of producing ball-bearing races and similar parts, which'includes the steps of: heating a rod of sectional material, cutting off a predetermined length from said heated rod, shaping said rod length into the form of a plate by pressing under heat, deforming said plate under heat into an intermediate work piece having coaxial annular portions integral with each other and arranged one partially within the other, the inner end face of the portion with smaller outer diameter and the adjacent outer end face of the adjacent portion with larger outer diameter being inclined in the same direction with respect to the axes of said portions so as to taper in the direction toward the outer end face of the portion with smaller outer diameter thereby defining a bridge between said portions, the crosssection of said bridge having a thickness substantially equalling the thickness of said coaxial portions; subsequently separating said coaxial portions while shaping said end faces of said portions to be transverse to the axes thereof, and punching a hole through the portion with smaller outer diameter.

Bausman Aug. 30, 1932 1 6 Schlaa Aug. 21, 1934 Matson Feb. 8, 1944 Koehring Nov. 14, 1944 Richardson Mar. 2, 1948 Dierback Oct. 14, 1952 FOREIGN PATENTS Great Britain June 19, 1930 Great Britain Feb. 7, 1945

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