Abstract:
A centerless grinding fixture for grinding multi-diamtter forms that do not lend themselves to be ground on a conventional centerless grinder. An example of such a part will be shown in which all surfaces,including the sides,may be ground without removing the workpiece from the grinding fixture.

Description:
This invention relates to a fixture for a centerless grinding machine and more particularly to a fixture for a centerless grinding machine capable of a rapid high precision placement of work on the machine. 
     FEDERALLY SPONSORED RESEARCH 
     No part of this patent application was developed with the aid of any federally sponsored research and development. 
     BACKGROUND AND RELATED ART 
     Centerless grinding machines are well known in the art. Typically they include a grinding wheel and a regulating wheel for controlling the rate that the work is fed through the machine. However setting up the work on the machine is time consuming when high precision work is required. Heretofore, when the job was completed, the machine settings for that work were lost when the work was removed from the grinder. Then if an another order for what work was received, the grinding machine had to be reset, which was expensive. 
     To overcome this problem, a fixture for a centerless grinder has been designed so that the machine settings are not lost when the work is removed. In this way, when an additional order for that work is received, the machine does not have to be reset. 
     To do this a regulating wheel assembly for each job is designed so it is independent of the grinding machine and can be removed and stored as a unit without disturbing the grinding machine settings. This leaves the main shaft free to accept other combinations of regulating wheels for grinding differently shaped forms. Then if additional orders for that work are received, the regulating wheel assembly for that job is simply replaced on the grinding machine, and the machine is ready for work. 
     What is needed therefore and comprises an important object of this invention is to provided a fixture for a centerless grinding machine which is designed so the regulating wheel assembly can be quickly and easily removed from the fixture without disturbing the machine settings. 
     Yet another object of this invention is to provide a centerless grinding machine where the regulating wheel assembly is independent of the grinding machine. 
     Another object of this invention is to provide a centerless grinding machine that is designed so the regulating wheel assembly can be quickly removed and replaced on the grinding machine. 
     These and other objects of this invention will become more apparent when better understood in the light of the accompanying drawings and specification wherein: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of the grinding fixture with a workpiece in position. 
     FIG. 2 is a perspective view of a typical work piece mounted on the fixture. 
     FIG. 3 is a top view of the grinding fixture. 
     FIG. 4 is a partial sectional view taken on the line  4 — 4  of FIG. 1 FIG. 4 showing a cross sectional view of the facing parallel side walls of the base and showing bearings mounted in the side wall hubs 
     FIG. 5 is a partial sectional view taken on the line  5 — 5  of FIG. 4 FIG. 3 showing in cross section of one of a pair of the clamps that tie the main shaft of the regulating wheel to the drive shafts mounted in the base or casting of the fixture. 
     FIG. 6 is an elevational view of the regulating wheel assembly showing the workpiece in position on the regulating wheel assembly. 
     FIG. 7 is an elevational view of the retaining washer taken on the line  7 — 7  of FIG.  6 . 
     FIG. 8 is a partial sectional view of a grinding wheel assembly designed to grind multiple surfaces on the workpiece. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1 of the drawing, the centerless grinding fixture  10  comprises a base or casting  20  which is mounted on a pair of sine bars  25 . As will become apparent below, the sine bars provide a means for precisely grinding the surface of the work piece to any angle with the use of Jo blocks placed under either bar. 
     The casting  20  is generally U-shaped with upstanding side walls  21  and  22 , see FIG.  4 . The facing surfaces of  21   a  and  22   a  of the walls are in a common plane, however, as shown the surfaces of the walls opposite the facing surfaces are offset to form bearing containing hubs  47  and  49 . Cylindrical holes are formed in each hub in axial alignment with each other and with precision bearings  46  and  48  mounted in each hole. 
     An electric motor  16  is mounted on the casting  20  to drive the regulating wheel assembly  34  through pulleys  17  and  19 , see FIG.  1 . Support or side arms  84  on both sides of the base are connected by screws  86  to a support plate or platform  82 . A platform  82   a  mounted on platform  82  supports guide assembly  26  which positions the workpiece  12  on the regulating wheel assembly  34 , see FIG.  1 . 
     The 45 degree support arms  84  are adjustable and slotted to keep the platform  82  at the required angle to the casting  20  during adjustment. This movement is controlled by the indicating wheel  96  which is connected to a rack and pinion (not shown). This positions the work piece  14  on the support plate  82  so it properly engages the regulating wheel assembly  34 . 
     The workpiece  14  is held in place by a flat spring  66  that presses against the circumference of the regulating wheel assembly  34 . The spring  66  is held by a spring assembly comprising a post  60 , which may be adjustable in height. This post positions a rod  62  inside the post in the horizontal plane so the spring can be rotated. The spring  66  is mounted in the slots formed in the rod  62  so it can be adjusted and are locked therein in a manner well known in the art, see FIG.  3 . 
     Referring again to FIG.  4 . it will be noted that the precision bearings  46  and 48 are mounted in the cylindrical openings in the hubs in such a WY that their centers define a centerline. Shafts  30  and  32  are inserted along the centerline through bearings  46  and  48 . In this way the axes of the drive shafts will be aligned with each other. As will be described below, a support shaft  40  for the regulating wheel assembly is connected to the facing ends of the shafts in such a way that its axis and will be aligned with the axes of the shafts  30  and  32 , see FIG.  4 . 
     The drive pulley  19  shown in FIG. 1 is connected to the shaft  30 . The shaft  32  may be extended to support other regulating wheels and castings, (not shown) in accordance with the requirements of the work. 
     As shown in FIG. 1, the guide blade  76  is adjustably mounted on the guide assembly  26  by means of bolts  78  that extend through the slots . In operation, the front edge of the guide blade  76  engages and positions the workpiece  14  with respect to the regulating wheel assembly  34 . For in through feeding, the blade  12  is set at an angle to the regulating wheel assembly which induces the workpiece to move forward under the grinding wheel. 
     As shown in FIG. 1 the casting  20  is attached to the side arms  9  which ride in channels machined at a 45-degree angle to the base plate. In this way, movement of the guide assembly  26 , maintains the angle at which the working end of blade  76  engages the workpiece  14 . 
     As seen in FIG. 6 the regulating wheel assembly  34 , in this particular embodiment, is composed in two sections  35  and  37 . These sections are mounted on a tubular secondary shaft  38  see FIG.  6 . The secondary shaft  33  is concentric with the closely fitting support shaft  40 . Shaft  40  is connected to and driven by drive shafts  30  and  32  by means of semi-circular clamps  50 , see FIGS. 4 and 5. 
     To hold the regulating assembly together, the shaft or tube  38  is threaded at its opposite ends. Threaded washers  42  are threaded at each end of tube  38  bearing against regulating wheel section  34  to hold the regulating wheel sections together. A threaded washer  44  is also threaded on one end of tube  33  bearing against washer  42 . These washers may be provided with notches (not shown) so they may be conveniently adjusted with a spanner wrench. In this way, when the washer  44  is tightened, the regulating wheel assembly is attached to the support shaft  40 , see FIG.  6 . 
     The regulating wheel sections  34  and  35  are separated on support shaft  40  by a spacer  36  whose size is determined by the requirements of the workpiece, see FIG.  6 . Positioning blocks  58  are secured to the facing surfaces  21   a  and  22   a  of casting  20  and are positioned by any suitable means so they extend toward each other an equal distance from the facing surfaces of the side walls. The lower halves  54  of the semi-circular support clamps  50  rest on positioning blocks  58  and are secured thereto by any suitable means, see FIG.  4 . 
     To attach the regulating wheel assembly  34  to the casting  20 , the support shaft  40  with the regulating wheel sections  35  and  37  are lowered between the side walls  21  and  22  of the casting until the opposite ends of the support shaft  40  rests on the lower ends  54  of the semicircular support clamps  50 , see FIG.  4 . In this position, the drive shafts  30  and  32  and support shaft  40  is aligned with each other. With this arrangement, when the lower ends or halves  54  of the clamps  50  are tied to the upper end  52  of the clamps  50  by means of screws  53 , the regulating wheel assembly is tied both to the support shaft  40  and the shafts  30  and  32 . Sufficient clearance between the clamps  50  on the sides of the casting, and the support or positioning blocks  58  allow free rotation of the shaft  32  and the regulating wheel assembly. In this way when the motor drives the drive shaft  40 , the regulating wheel assembly rotates. 
     As seen in FIG. 4, when the lower end  54  of clamps  50  are disconnected from the upper end  52  of the clamps, the entire regulating wheel  34  and its supporting shaft  40  may be lifted out of the casting  20  and removed and stored for future use when grinding the same workpiece. 
     In operation, to attach the regulating wheel assembly to the base or casting  20 , it is simply lowered between the spaced walls  21  and  22  until the opposed ends of the support shaft  40  engage and are supported by the fixed semi-circular portions  54  of the clamps  50 . These supports extend toward each other with one half of the width of each semi-circular support on each section of the support shaft  40 . In this way when the upper ends or halves  52  of the semi-circular clamps are positioned around the shaft  32  and are securely bolted to the lower ends  54  by any suitable means, the shafts  30  and  32  and support shaft  40  will be in axial alignment and tied to each other. 
     It is noted that the regulating wheel is consructed for a particular work piece, and when grinding the job is done, the semi-circular upper ends  52  of the clamps  50  are separated from the semi-circular lower ends  54 , and the entire regulating wheel assembly is simply lifted off the casting  20  and stored away for future use. Later when there is an order for additional work pieces for which the regulating wheel was designed, the entire regulating wheel assembly is simply placed on semi-circular lower end  54  of clamps  50 , and the semi-circular upper ends  52  of the clamps  50  are clamped to the lower end  54  and the centerless grinder is ready for operation. This operation does not affect the bearings  46  and  48 , on the support so that the tolerances of the grinding machine are not affected. 
     The spacing between regulating wheel sections  35  and  37  permit a grinding wheel to be designed so that more than one surface of the work can be ground with a single pass of the grinding wheel. As shown in FIG. 8, the grinding assembly  5  is formed from two sections  7  and  9 . These sections are held apart by a spacer  11  which is also a grinding surface. Tbe facing peripheral edges  13  of the sections  7  and  9  are also grinding surfaces. 
     With this arrangement, the grinding wheel assembly can be lowered onto the workpiece  12  to grind the opposed surfaces  13  of the large diameter part of the work piece  14  and the grinding surface  11  will at the same time grind the planar surface of the small diameter part of the workpiece, see FIG.  2 . 
     The regulating wheel  34  shown in FIG. 6 is formed in two sections, but depending on the demands of the work, the regulating wheel can be formed with multiple sections. But in any event the regulating wheel would be attached to the casting the same way as with the two section regulating wheel shown in FIG.  4 .