US2969623A

US2969623A - Size gauging device

Info

Publication number: US2969623A
Application number: US706030A
Authority: US
Inventors: Kenneth D Mehlhope; Arthur H Faulhaber
Original assignee: Cincinnati Milling Machine Co
Current assignee: Milacron Inc
Priority date: 1957-12-30
Filing date: 1957-12-30
Publication date: 1961-01-31
Anticipated expiration: 1978-01-31
Also published as: GB847344A; FR1217931A; DE1122406B

Description

Jan. 31, 1961 K. D. MEHLHOPE ET AL 2,969,623

SIZE GAUGING DEVICE Filed Dec. 30, 1957 3 Sheets-Sheet l i I I 23 i l7 INVEIJTO? KENNETHDJVEHL HOPE. 24 Z3 gRTHuR H. FflUL HABER. /4 5' ywyi 77M 22 25 I ATTORNEYS.

srzE GAUGING DEVICE Kenneth D. Mehlhope and Arthur H. Faulhab'e'r, Cincinnati, Ohio, assignors to The CincinnatiMilling Machine Co., Cincinnati, Ohio, a corporation of Ohio Filed Dec. 30, 1957, Ser. No. 706,030

6 Claims. (Cl. 51-103) This invention relates to an improved size gauging device and, more particularly, to a gauge which is adapted for use with centerless grinding machines to provide continuous measuring of the work as it is being ground to size. The present invention has particular reference to a gauge which utilizes the tilting shoe of a work support to sense the diameter of the work piece and provide a signal when the work piece has reached a predetermined size. With this arrangement, it is possible to provide a simple, sturdy, and sensitive type of gauge which is H11? affected by the flow of coolant over the workand which will afford a high degree of repetitive accuracy? in the sizing of the work pieces.

Accordingly, it is an object of the present invention to provide an in-process gauge for centerless grinding machines which is of simple, study construction and which is capable of gauging the work being ground to very close tolerances.

Another object of the invention is. to provide agauge which utilizes the tilting movement of a supporting shoe in a centerless type grinding machine to produce an indication of the changing diameter of the workas the grinding operation proceeds.

Another object of the invention is to utilize a signal provided by the gauge when the shoe has tilted to a me determined position to reduce the feed rate of the grinding wheel toward the work in order to finish grind the work to final size at which time asecond signal from the gauge will stop further feeding movement of the wheel.

With these and other objects in view which will become apparent from the following description, the invention includes certain novel featuresof construction and combinations of parts, the essential elements of which are set forth in the appended claims, and a preferredform'or embodiment of which willhereinafter be'described with reference to the drawings whichaccompany and form'a part a of this specification. In the drawings:

Fig. 1 is a fragmentary View illustrating the tiltingshoegauge.

Fig. 2 is a plan view of the structure showninlig, 1.

Fig. 3 is a-schematic view showing the hydraulically.

operated infeedmechanism of the grinding machine.

Fig. 4 is a schematic view of the pneumatically operated gauging equipment.

Fig. 5 is a wiring diagram showing the electrical control circuits for the infeed mechanism.

Similar reference characters designate similar or identical elements and portionsthroughout-the specification and throughout the different views of the drawings.

In-the present application the invention is shown applied to a centerless grinding machine of the type disclosed in the Binns and Haas Patent No. 2,478,562, granted August 9, 1949, forGrinding Machine, this machine also being shown in" the more recent patent to Schonhoft' et al'. 2,795,088, granted June 11, 1957, for Microcentric Grinder. In the machine shown and described in the aforementioned patents, the work tobev ground is sup 2,969,623 Patented Jan. 31, 1961 ICC ported for revolution ona pair of shoes carried by a workjournaled in an oscillatable wheel head, is'moved to and-- from the work by swinging movement of the wheel head."

This movement is efiected by a rapid traverse mechanismwhich moves the wheel intoand out of operative grinding range, and by an infeed mechanism which serves tofeedthe'wheel into the'work after it has been moved into position by the rapid traverse mechanism.

In accordance with the presentinvention, one of the" supporting shoes is pivotally mounted on the work sup-. port so as to allow it to change its position in conformity with the changing diameter of the work as it is ground to" The position of theshoe is sensed by an air gauge which includes an orifice disposed adjacent an abutment surface provided on an arm moving with the shoew Changes in airpres'sure, resulting from movements of the shoe, serve to operate-pressure switches which control the;- infeed mechanismof the grinding machine so as to govern the feed rate and stopping of the infeed movement of the:

size.

wheel in accordance with the diameter of the work. The

grindingwheel is, thereafter automatically retracted to itsstarting position to place it in readiness for the next grinding cycle.

In the present application only those portions of the previously existing structure which are essential" for an." understanding of the presentinvention are shown in the,

accompanying drawings. in Fig. 1, there is shown a bed plate 10 on which is mounted the work supportll to which is bolted aplate 12; A-pair of work supporting;-

shoes

13 and 14 carried bythe plate 12 serve to support a work piece 15 for rotation bya driver 16 (Fig. 2). The I end' face 17 of the driver is so formed as to provide a frictional drive for the work piece 15 which is held in engagement therewith'by any suitable means, for example, by magneticattraction produced by an electro-magnet in--' corporated in the driver 16. The work piece 15 is thereby rotated

onthe shoes

13 and 14 as it is being ground bya-' grinding wheel 18 (Fig. 1).

Intlie present embodiment of the invention, the shoe 13 is'the stationary'shoe and' is adjustably secured to the plate l2-by means of bolts 20 which pass through elon-' gated slots provided in the shoe and thread into tapped holes formed in the plate 12. The shoe 14 is the tilting shoe and is arranged to pivot about an axis 21 (Fig. 2)"

which is parallel to the longitudinal axis of the work piece 1 15; The shoe 14 is supported for pivotal movement on a bracket 22 which is adjustably secured to the plate 12 in the same manner as the shoe13, the-bolts which hold the bracket to the plate being removed in Fig. 1 to better illus- The bracket 22 is provided witha trate this construction. projecting lug 23 which is suitably apertured to forni seats for balls 24. One of the balls 24 is adapted also to seat in a recess provided therefor in a plug 25 while the" other ball is adapted to seat in a recess provided in the end of a screw 26 which threads into a tapped hole pro} vided in the shoe 14' where it is held by a lock nut 27. The shoe 14 is thereby permitted limited rocking move:

ment about the axis 21which passes through the center of the balls and the longitudinal axis of the screw 26.

Secured to the shoe 14 is warm 28 provided with'an abutment surface 29 which lies in front of an orifice 30 provided on the end of a nozzle 31. The nozzle is sup ported by an arm 32 depending from the bracket 22 The end which it may be clamped in adjusted position by a thumb screw 33.

As the work piece 15 is reduced in diameter by the grinding wheel, the shoe 14 will rock clockwise about its pivot and thereby move the abutment surface 29 closer to the orifice 30 so as to restrict the flow of air issuing from the orifice. The back pressure thus built up in the pneumatic circuit connected therewith serves to operate pneumatic switches in a manner hereinafter to be described so as to exert the desired control over the infeed mechanism of the grinding machine.

The portions of the infeed mechanism which are necessary for an understanding of the present invention are shown in Fig. 3 of the drawings and include a rapid traverse cylinder 35 which moves with the wheel head of the machine. Located within the cylinder 35 is an adjusting sleeve 36, which is closed at its upper end. Adjustment of the sleeve within the cylinder is effected by a screw 37 bearing against the top of the sleeve by means of which the stroke of the rapid traverse cylinder may be adjusted as desired.

Operating within the sleeve 36 is a piston 38 to which is secured a piston rod 39 which passes through a gland provided in the bottom of the cylinder 36. The lower end of the piston rod 39 bears against a roller carried by one arm 40 of a bell crank 41. The bell crank is pivoted on a stud 42 carried by the framework of the machine and is provided with a second arm 43 provided with an abutment face 44 which bears against the wedge-shaped face of a nut 45 threaded on the end of a feed bar 56. Hence, as hydraulic fluid under pressure is admitted to the chamber 46 formed between the upper end of the piston 38 and the upper end of the sleeve 36, the piston 38 will be held against movement by the bell crank 41, thereby causing the cylinder 35 to move upwardly and rock the wheel head about its pivot (not shown) so as to move the grinding wheel toward the work piece.

Feeding movement of the grinding wheel toward the work piece is effected by a hydraulic motor 50 which drives a worm 51 meshing with a worm wheel 52. The worm wheel is formed integral with a nut 54 which is journaled for rotation without translation in a frame member 53. As the nut revolves, it serves to feed a screw 55 having threads meshing therewith in one direction or the other depending on the direction of rotation of the motor 50. The screw 55 is formed as a part of the feed bar 56 which, at its left hand end (Fig. 3), passes through the arm 42 of bell crank 40 where it receives the nut 45. The bar 56 is prevented against rotation by means of serrations 57 formed thereon which mesh with corresponding serrations formed in an aperture provided in the frame member 53. Hence, as the motor 50 is rotated to move the bar 56 to the right as viewed in Fig. 3, the grinding wheel will be advanced toward the work so as to effect grinding of the work by the wheel. After the work piece has been reduced to size, the motor 50 is reversed to feed the bar 56 to the left and hydraulic fluid is permitted to escape from the chamber 46 so as to permit the wheel head to rl'gturrg to its retracted or starting position as shown in Hydraulic fluid under pressure for operating the cylinder 35 and the motor 50 is provided by a pump 60 which withdraws hydraulic fluid from a sump and delivers it under pressure to a fluid pressure line 61. Constant pressure is maintained in the line 61 by means of a relief valve 62 connected to the outlet side of the pump 60 which returns excess fluid into a sump or reservoir. The flow of fluid under pressure to the cylinder 35 is controlled by a solenoid operated valve 63. When the solenoid ZSOL for this valve is energized, the spool 64 of the valve will be moved down to connect a line 65 with the pressure line 61. Hydraulic fluid under pressure will thereby be delivered through a check valve 66 '4 and a conduit 67 into an annular groove 68 formed on the periphery of the sleeve 36. The groove 68 is communicatively connected by ports 69 with the chamber 46 so that fluid under pressure may enter the chamber and lift the cylinder 35 and thereby the wheel head so as to move the grinding wheel from the retracted position to its work engaging position.

When the solenoid ZSOL is deenergized, the line 65 is connected through a low pressure relief valve with a return line 8 6 which leads to the reservoir. Hence, under these conditions, fluid will be permitted to flow from the chamber 46 through the ports 69, conduit 67, throttle valve 87 and line 65 to the relief valve 85 and thence to the reservoir. A controlled rate of retraction of the wheel head to its starting position will thereby be effected as the unbalanced weight of the wheel head forces the cylinder 35 down on the piston 38.

At the conclusion of the rapid traverse movement of the grinding wheel toward the work piece, a limit switch ZLS will be operated by an abutment 93 provided on the cylinder 35. As will hereinafter be described in connection with the electrical circuits which control the operation of the feeding mechanism, operation of the limit switch causes solenoids 13SOL and 14501. to be energized thereby initiating operation of the motor 50. When the solenoid 13SOL is energized, a spool 95 of a pilot valve 96 is moved down, thereby connecting a line 97 to the pressure line 61 and a line 98 to a line 99 which communicates with the return line 73. When solenoid 14SOL is energized it will cause the plunger 100 of a blocking valve 101 to be moved down thereby connecting the line 97 with a motor line 102. At the same time, a motor line 103 will be connected with a line 104 which is connected to one of the ports of a rate valve 105 which controls the fine feed rate of the grinding wheel toward the work piece. The other port of valve 105 is connected by a line 106 with the line 98 which is connected to reservoir when solenoid 13SOL is energized. At this time the solenoid 17SOL will also be energized, thereby raising the spool 109 of a feed rate control valve 110, thereby connecting a branch line 111 of line 104 with a line 112 which is connected with one port of a rate valve 113. This valve is adapted to control the coarse feed rate of the grinding wheel toward the work and the remaining port of this valve is connected by a line 114 with the line 98 and thereby to reservoir.

Under these conditions, the motor line 102 will be connected to pressure line 61 while the motor line 103 will be connected to reservoir through the fine and coarse rate valves 105 and 113. The motor 50 will thereby be caused to run in a forward direction at a relatively high speed so as to move the grinding wheel against the work at a coarse feed rate. After the work has been ground to a predetermined diameter, as determined by the gauge, the solenoid 17SOL will be deenergized, thereby permitting the spool 109 to return to the position shown in Fig. 3. This will cause the coarse rate valve 113 to be removed from the circuit and cause all of the return flow from motor line 103 to pass through the fine rate valve 105. The movement of the grinding wheel against the work .will thereby be reduced to a fine feed rate as the work piece approaches its finish diameter. When the work piece reaches final size, the gauge will provide an appropriate signal and cause the solenoid 14SOL to be briefly deenergized, thereby connecting motor line 102 to a branch 115 of line 97 and the motor line 103 to the line 97. Thus, equal pressure will be applied to both of the motor lines, thereby rapidly stopping the motor and locking it against further rotation. By means of the electrical control circuit shown in Fig. 5, the solenoid 2SOL will now be deenergized, thereby permitting the spool 64 of valve 63 to return to the position shown in Fig. 3. This will cause line 65 to be connected to the reservoir line 86 through the relief valve 85 and Fig. 3, thereby retracting the grinding wheel from its grinding position. At the same time, solenoids 14SOL and 25SOL will be energized, the latter solenoid being effective to move a spool 119 of a bypass valve 120 downwardly so as to connect a branch 121 of line 102 to a branch 122 of return line'73. sure line 61 will be connected'through a check valve 123 with the motor line 103, thereby urging the motor 50 to run in the reverse direction to return the feed bar 56 toward the left as viewed in Fig. 3. Movement of the bar 56 to the left will continue until a dog 126, which is'adjustably mounted on a threaded extension 127 of the bar 56, will operate a limit switch 12LS and thereby deenergize solenoids 25SOL and 14SOL. Motor 50 will thereby again be placed under the control of

valves

96 and 101 and, since solenoids 13SOL and 14SOL are now de-energized, the motor will be stopped and' the mechanism will be ready for the next grinding cycle;

The pneumatic gauging circuit and the electrical contacts controlled thereby are shown in Fig. 4 of the drawing. An air supply tube 130 connected to a suitable source of air under pressure is connected to a regulating valve 131 which supplies air at a predetermined constant pressure to a line 132. This line is connected to a variable restriction represented by throttle valve 133 which is connected by a line 134 and a flexible tube 135 with the nozzle 31 (see also Fig. l) of the gauge. Hence, the pressure of the air in line 134 will vary in accordance with the spacing between the'orifice 30 and the abutment surface 29 on the lower end of the arm 28. A pair of pneumatic relays 136 and 137 are provided with a source of constant reference pressure through

linesv

138 and 139 which are connected to the outlet port of a regulating valve 140 which is supplied with air from the line 130. The relays 136 and 137 are connected by

lines

141 and 142, respectively, with the line 134 and control the flow of air to pressure

switches

143 and 144 to which they are connected by

lines

145 and 146. As indicated in Fig. 4, the switch 143 includes normally open contacts 1A and normally closed contacts 1B, while the switch 144 is provided with normally open contacts 1C and normally closed contacts 1D. When the gauge senses the approach of thework piece to the predetermined final size, the pressure switch 143 is operated to close contacts 1A and open contacts 1B. When the part reaches final size; the pressure switch 144 is operated to close cpntacts 1C and open contacts 1D.

The means whereby these contacts are utilized to control the infeed mechanism of the grinding machine is shown by the wiring diagram (Fig. 5) where the contacts of the pressure switches are shown located in

lines

11, 13, 15, and 16. Energizing current for the control relays and operating solenoids shown in Fig. 5 is supplied by

conductors

150 and 151 which are connected to a suitable source of energizing current. When it is desired to initiate a grinding cycle, a start push button shown in line 1 of the electrical diagram is depressed, thereby energizing a control relay 3CR (line 1) which locks in through contacts 3CR in line 2. Depression of the start push button also energizes a control relay 4CR (line 5) through wire 152 and the normally closed contacts of a timer relay 1TR (line 3). When relay 4CR is energized, the contacts 4CR in line 5 close, thereby locking in this relay through the 3CR contacts in line 2. At the same time, the contacts 4CR in line 6 are closed, and, since the contacts of limit switch 12LS in line 7 are held closed at the start of the cycle by the dog 126 (Fig. 3), relay SCR (line 8) will be energized. The contacts 5CR in line 8 will thereby be closed and lock in this relay around the contacts of limit switch 12LS. Energization of relay SCR will also cause the contacts of this relay in line 19 to close, thereby energizing solenoid 2SOL (see also Fig. 3) and initiate rapid traverse of the grind- At the same time, pres-- ing wheel toward the*wor-k. At'the endof therapid: traverse stroke, the contacts of limit switch 2LS in'line, 9-will be closed, thereby energizing a control relay 76R (line 9). The contacts'of this relay in line '20 will there '1 by be closed so asto energize solenoid 13SOL and'op-- erate'the pilot valve 96 (Fig. 3). The contacts 7CR= in line 22 will also be closed and cause solenoid 14SOL to be energized since the contacts of relay 12CR in line 22 are also closed at this time. This results from the fact that control relay 120R (line 16) is'energized through contacts SCR (line-11), the normally closed contacts 1D (line 16), and the normally closed contacts: of control relay 11CR in line 16. Energization of sole'-* noid 14SOL will cause the blocking valve 101 (Fig. 3)

to be moved to the unblocking position and thereby cause the hydraulic motor 50 to run in' the feed direction at a coarse feed rate. This is due to the fact that the feed rate" control valve (Fig. 3) is held operated at this time by'energization' of'solenoid 17SOL (line 21). En-' ergization of this solenoid results from the factthat the contacts 10CR of a control relay 10CR (line 13) are closed due to energization of this relay through contacts SCR (line 11), normally closed switch contacts 1B (line 13), and the normally-closed contacts of relay 9CR'in line 13.-

The coarse feed rate will continue until the first or approach signal is produced by the gauge whereupon the contacts 1A in line llwillbe closed and the contacts 1B in line 13: will be opened. Closure of contacts'lA will cause control relay 9CR (linell) to be energized: since the contacts 12CR (line 11) are'now closed. Relay" 9CR will be locked inaround the contacts 1A by closureof the contacts 9CR in line 10.

Relay 10CR now being deenergized, the contacts of this relay in line 21 will be'opened, thereby deenergizing' solenoid. 17SOL and causing the feed rate control valve 110 (Fig; 3) to return to the position shown in Fig. 3 whereby the coarse rate valve 113 is cut out of the circuit, and all of the return fluid from the motor 50 is forced to" flow through the fine-rate valve 105. Thewheel will now continueto advance at-a fine feed rate until the second and 'fi'nal signal is given by the gauge signifying that thework' has been ground to finish size. At this time thecontacts 10 in line 15 will be closed, and the contacts" 1D in line 16- will be opened. Therefore, relay 110R will be energized andrelay 12CR will be deenergized; thereby causing the contacts 12CR in line 22 to open: Solenoid 14SOL is thereby deenergized, and motor 50 is stopped. Also, closure of contacts 110R in line 17 will lock in the relay 11CR around the contacts 5CR in

line

11 and 10 in line 15. The energization of relay 110R also closes contacts 11CR in line 3, thereby energizing relay 1TR which causes delay contacts 1TR in line 5 to open. This deenergizes relay 4CR and drops out relay SCR due to the opening of contacts 4CR in line 6. Solenoid ZSOL is thereby deenergized by the opening of contacts SCR in line 19 and the valve 63 (Fig. 3) is returned to its initial position in which the cylinder 35 is connected to reservoir through throttle valve 87 and the low pressure relief valve 85. The grinding Wheel is thereby withdrawn from the work and the contacts of limit switch ZLS in line 9 will be opened thereby deenergizing relay 7CR. This causes solenoid 13SOL (line 29) to be deenergized and the valve 96 to return to its original position in which the line 97 is connected to reservoir, and the line 98 is connected to pressure.

When relay 4CR was deenergized, its contacts in line 23 were closed, thereby energizing solenoids 14SOL and ZSSOL to operate the by-pass valve (Fig. 3) and cause motor 50 to run at full speed in the reverse direction. The motor will continue to operate in this manner until limit switch 12LS is operated to deenergize relay 13CR. The contacts of this relay in line 23 then open and deenergize solenoids 14SOL and 25SOL to stop the motor 50. When relay 13CR is deenergized, its contacts in line 17 are caused to open, thereby deenergizing relay 11CR. This will drop out relay lTR (line 3) thereby permitting the contacts of this relay in line to close in readiness for the next grinding cycle which finalilylbe initiated by again depressing the start button in A visual indication of the operation of the gauge is provided by an amber signal light 155 (line 12) and a green signal light 156 (line 14) which are controlled by contacts 1A and 1C, respectively, to indicate first the approach of the work to final size and finally the arrival of the work at its finished diameter.

While we have described our invention in connection with one possible form or embodiment thereof and have used, therefore, certain specific terms and language herein, it is to be understood that the present disclosure is illustrative rather than restrictive, and that changes and modifications may be resorted to without departing from the spirit of the invention or the scope of the claims which follow.

We claim:

1. A device for measuring the diameter of a cylindrical surface on a work piece as the surface is being ground to size in a centerless grinding machine, comprising a pair of supporting shoes adapted to engage the cylindrical surface to be ground at two circumferentially spaced apart locations, pivot means for supporting one of said shoes for rocking movement about an axis parallel to the longitudinal axis of the cylindrical surface, said pivot means being located beneath the work-engaging surface of said one shoe and in alignment with the work-engaging surface of the shoe and the center of the workpiece, and means controlled by said one shoe as it is rocked about said pivot means in response to changes in the diameter of the cylindrical surface during grinding for varying a physical quantity in accordance with the instantaneous diameter of the surface on the work piece.

2. The device of claim 1 wherein the last mentioned means includes a pneumatic circuit having an orifice, and means on said one shoe for controlling the flow of air from said orifice in accordance with the position of the shoe.

3. In a centerless grinding machine having a grinding wheel, a pair of shoes for supporting the work piece to be ground, and means for feeding the grinding wheel and the shoes toward one another so as'to cause the grinding wheel to abrade the surface of the work piece supported on said shoes, the combination of means for supporting one of said shoes for pivotal movement about an axis parallel to the longitudinal axis of the work piece, and means controlled by said one shoe as it changes its position in accordance with change in the diameter" of the work piece during grinding for stopping said feeding means when the work piece has reached a predetermined size.

4. The centerless grinding machine of claim 3 wherein said stopping means includes a pneumatic circuit having an orifice, and means on said one shoe for controlling the flow of air from said orifice in accordance with the position of the shoe.

5. In a centerless grinding machine having a grinding wheel, a pair of shoes for supporting the work piece to be ground, means for feeding the grinding wheel andthe shoes toward one another so as to cause the work piece supported on said shoes to be abraded by the grinding wheel, means for controlling said feeding means to reduce the feed rate as the work piece approaches a predetermined diameter, and means for stopping said feeding means When the workpiece reaches said predetermined diameter, the combination of means for supporting one of said shoes for pivotal movement about an axis parallel to the longitudinal axis of the work piece, and means controlled by said one shoe as it changes its position in accordance with changes in the diameter of the work piece during grinding for first operating said feed rate reducing means as the work piece approaches its final size, and thereafter operating said stopping means to stop further infeed movement of the Wheel by said feeding means when the work piece has reached final size.

6. The centerless grinding machine of claim 5 wherein said last-named means includes a pneumatic circuit having an orifice positioned adjacent said one shoe, and means on said one shoe for controlling the flow of air from said orifice in accordance with the position of the shoe.

References Cited in the file of this patent UNITED STATES PATENTS 1,885,233 Cole Nov. 1, 1932 2,007,507 Steiner July 9, 1935 2,603,043 Bontemps July 15, 1952