US3113563A

US3113563A - Grinding wheel crush dressing apparatus

Info

Publication number: US3113563A
Application number: US104928A
Authority: US
Inventors: Daniel C Hughes
Original assignee: Royal Master Grinders Inc
Current assignee: Royal Master Grinders Inc
Priority date: 1961-04-24
Filing date: 1961-04-24
Publication date: 1963-12-10
Anticipated expiration: 1980-12-10

Description

Dec. 10, 1963 D. c. HUGHES 3,113,563

GRINDING WHEEL. CRUSH DRESSING APPARATUS",

Filed April 24, 1961 2 Sheets-Sheet l "IIIHHHHIH""HHIHWWH HIM] ER-RIDE 37 ICLUTCH l SPEED REDUCER U 3 45 INVENTOR ANIEL C. UGHES ATTNEY Dec. 10, 1963 D. c. HUGHES GRINDING WHEEL CRUSH DRESSING APPARATUS Filed April 24, 1961 2 Sheets-Sheet 2 INVENTOR DANIEL C. HU G /4 4-1. NEY

United States Patent 3,113,563 GRINDZNG WHEEL CRUSH DRESSENG APPARATUS The present invention relates to the dressing of grinding wheels, and, more particularly, to crush dressing apparatus for the work wheel of a centerless grinder or the like.

In the past, centerless grinders have been utilized for rapidly producing one or more parts which are generally circular in cross-section. Such machines generally compn'se a work Wheel or grinding wheel which is con-toured to shape the articles from circular stock, a regulating or feeding wheel for holding the stock against the work wheel, and a work rest for supporting the stock between the Wheel while it is being ground to the desired shape.

The work whee-l usually is contoured or crush dressed by rotating the same and forcing against it a freely rotatable wheel of harder material than the work wheel which wheel is shaped to produce the desired contour on the work wheel. It has been customary to mount such apparatus at the back of the grinding machine so that the work wheel can be redressed from time to time to maintain its contour within close tolerances without removing the work wheel from the machine.

In operation of the grinder, the work wheel usually is operated at a high speed, for example, at about 2100 r.p.m., and :provision is made for operating the work wheel at a lower speed, for example at about 50 r.p.m. while dressing or redressing the same.

One of the difficulties encountered with such an arrangement is that, when the operator desires to dress or redress the wheel, he may forget to switch the work wheel drive to the lower operating speed and feeds the dressing wheel into the work wheel While operating at a high speed with the result that damage is inflicted to the surface of the work wheel and/ or its bearings.

Accordingly, an object of the present invention is to provide crush dressing apparatus of the foregoing type wherein provision is made for automatically switching the work wheel drive to its lower speed when attempt is made to apply the crush dressing wheel to the work wheel and to maintain the drive at that lower speed until the dressing wheel has been retracted.

Another object is to provide such apparatus wherein the dressing wheel cannot be applied to the work Wheel until the work wheel is being driven at its lower speed.

Another object is to eliminate electrical hazards.

A further object is to accomplish the foregoing in a simple, practical, reliable and economical manner.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawings, forming a part of the specification, wherein:

FIG. 1 is a fragmentary plan View of a grinding machine having crush dressing apparatus attached thereto provided with a drive for operating the Work wheel at its higher and lower speeds, and a simplified wiring diagram for controlling the drive.

:FIG. 2 is an enlarged fragmentary sectional view taken along the line 22 on FIG. 1 illustrating a switching arrangement for the drive.

FIG. 3 is a fragmentary perspective View illustrating another switching arrangement.

FIG. 4 is a sectional view taken horizontally through the switch shown in FIG. 3.

Referring to FIG. 1 of the drawings in detail, there is shown a base 9, a work wheel 10 mounted on the base and drive-n by a motor ll. through conventional mechanism herein illustrated schematically for simplicity as a chain and sprocket arrangement 12, and work wheel crush dressing apparatus 14 in accordance with the present invention.

The apparatus '14- generally comprises a horizontal bracket 15 which is mounted on the base 9 adjacent an opening =8 in a conventional guard or casing (partially shown) for the work wheel, a dressing wheel 16, mechanism 117 for moving the dressing wheel into and out of contact with the work wheel It by way of the opening, and a switching arrangement 11% for the motor.

The dressing wheel do is rotatably supported by bearings 19 on a carriageg 28 which is mounted on a slide 21 supported by the bracket :15 between side walls 22 thereof. A threaded spindle 23 is mounted for rotation by a crank or hand wheel 24 at the outer end of the bracket, and the spindle is threaded through the carriage 29 to effect lengthwise movement thereof along the slide -21.

As shown in FIGS. 1 and 2, the switching arrangement 18 comprises a pin or rod 25 extending transversely through an opening 13 in a side wall 22 of the bracket at about the middle thereeof but closer to the inner end of the bracket, a spring 26 for urging the rod 25 inwardly into the path of the carriage 2d, a switch 27 on the exterior of the side wall of the bracket having an element 28 adapted to be operated by the outer end of the rod 25, a spring 33 for maintaining the switch in normally open position and to cause the element '28 to follow the rod 25, and a cam or wedge 29 at the side of the carriage 24) for operating the rod 25.

The wedge 29 is constructed and arranged so that the rod 25 is operated by it to close the switch 27 when the carriage approaches a fully retracted position (FIG. 1) and to allow the switch to open by means of the

springs

26 and 33 when the dressing wheel '16 approaches the work wheel ll).

Another way of accomplishing this is shown in FIG. 4 which comprises utilizing the spring 33 in the switch 27 to urge the rod 25 outwardly by the switch operating element 28, and piviotally mountting a bar or lever 30 on the side wall 2% at 31 adapted to be engaged by a pin 32 on the carriage 20 to close the switch only when the carriage has been fully retracted.

Preferably, the switching arrangement is so located that the work wheel is operating at its lower speed within the time the dressing wheel can be moved into engage ment with the work wheel by the relatively slow movement of the carriage 20 which is effected by the screw threaded spindle 23. it is also within the concept of the present invention thta braking means under the control of the switching arrangement could be provided for slowing down the work wheel or its drive to the lower speed at which it is safe to bring the dressing wheel into engagement with the work wheel.

In FIG. 1, a drive for the work wheel It} is shown which includes the main motor 1d having its output connected to the work wheel, an auxiliary motor 34, a speed reducer 3'5, an over-ride clutch 36 connected to the out put of the speed reducer, a chain and sprocket drive 3-7 connecting the output of the motor 34 to the input of the speed reducer, a chain and sprocket drive 3 8 connecting the over-ride clutch to a counter-shaft 39 of the motor 111, and a control network about to be described. With this arrangement, the motor 34 when energized while the motor 1 1 is de-energized drives the work wheel at low speed through the chain and sprocket drive 37, the speed reducer 35, the clutch 36, the chain and sprocket drive 38 and the motor 1 1. However, when the motor 11 is energized and the motor 34 is (lo-energized, the over-ride clutch prevents the motor :11 from driving the speed reducer 35.

The control network shown in FIG. 1 includes a relay 40 under the control of the switch 27, a source of power for the motors 1-1 and 34 such as

lines

41 and 42, a manually operable main switch 44 for turning on and shutting off the source of power, a manually operable switch 45 in a branch of the line 41 for starting and stopping the motor 1111, a manually operable switch 46 in another branch of the line 41 for starting and stopping the motor 34, a double throw switch 47' operated by the relay 40 for selectively connecting and disconnecting the motors 11 and 34 to the line 42 through

contacts

48 and 49, respectively, and a switch arm 56' connected to the line 42, and a transformer 51 connected across the

lines

41 and 42 for supplying a low voltage for energizing the relay 40' by means of the switch 27. The low voltage supply and relay arrangement eliminates the necessity of running the line voltage through the switching arrangement 18, whereby electrical hazards in the crush dressing apparatus is avoided.

In operation, when it is desired to operate the grinding machine, the main switch 44 and the main motor switch 45 are closed. However, if the dressing wheel has not been retracted, the switch 47 will be in a position whereby the line 42 will not be connected to the motor '11 and the motor 111 cannot be energized. Upon properly retracting the dressing Wheel, the switch 27 will energize the relay 40 to connect the motor 11 to the line 42 through the contact 48 and the switch arm 50 as shown in FIG. 1.

When it is desired to dress or redress the Work wheel, the switch 45 should be opened, but, if the operator forgets to do so and causes the dressing wheel to move towards the work wheel, the switch 27 opens to deenergize the relay 40* which causes the switch arm '50 to disengage the contact '48 and to engage the contact 49 whereby the motor 1 1 is automatically cut out 'md the motor 34 is cut in for low speed operation of the work wheel upon closing of the switch 46.

In the event the operator forgets to open the switch 46 and shut off the motor 34 when it is again desired to operate the grinding machine, this is efiected automatically by the relay 40 as the dressing wheel is properly retracted. Consequently, neither the work w eel nor the motor 34 and its drive connections to the motor 11 can be dam-aged by carelessness on the part of the operator.

From the foregoing description, it will be seen that the present invention provides improved crush dressing apparatus which does not subject the operator to a hazardous condition and prevents damage to the machine.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that if, all matter herein is to be interpreted as illustrative and not in any limiting sense.

[I claim:

1. In a centerless grinder, the combination of a work wheel; a support adjacent said work wheel and extending substantially radially outwardly therefrom; a horizontally extending slide on said support; a carriage slidably mounted on said slide; crush dressing means mounted on said carriage for engaging said work wheel; means for moving said carriage towards and away from said work wheel; co-operating first and second motor means for respectively effecting rotation of said work wheel at a speed and a much lower speed; and switch means for preventing energization of said first motor means when said crush dressing means approach said work wheel and for selectively energizing and tie-energizing said first and second motor means, said switch means comprising at least a control switch, and control switch operating means including a projection on said carriage, movable means having a portion extending into the path of said projection and having a portion for actuating said control switch, spring means for opposing actuation of said control switch and for biasing said movable means to place the first mentioned portion thereof into the path of said projection said projection and said movable means being arranged to maintain said control switch in a position to prevent energization of said first motor means until said carriage has been retracted to move said crushing means a given distance away from said work wheel, which distance is less than the distance said carriage can move on said slide, said first motor means having a shaft and means on said shaft for effecting rotation of said work wheel, a speed reducer driven by said second motor means, and an over-ride clutch driven by said speed reducer and connection for driving said shaft at a low speed.

2. A grinder according to claim 1, wherein said first mentioned portion of said movable means is a pivotally mounted lever having a first arm engageable by said projection and having a second arm, said second mentioned portion of said movable means is a slidably mounted rod having a first end engaging said second arm and having a second end, and said control switch includes an element engaged by said second end of said rod.

3. In a centerless grinder according to claim 1, wherein said switch means include a low voltage operable relay controlled by said control switch, and said control switch is mounted on said support.

References (Zited in the file of this patent UNITED STATES PATENTS 2,457,318 Polk Dec. 28, 1948 2,534,941 B aldenhofer Dec. 19, 1950 2,535,183 Wilson Dec. 26, .1950 2,571,293 Ross Oct. 16, 1951 2,576,201 Wilson Nov. 27, 1951 2,586,755 Wilson (Feb. 19, 1952 2,636,321 Wilson Apr. 28, 1953 2,652,661 Flanders et al Sept. 22, 1953

Claims

1. IN A CENTERLESS GRINDER, THE COMBINATION OF A WORK WHEEL; A SUPPORT ADJACENT SAID WORK WHEEL AND EXTENDING SUBSTANTIALLY RADIALLY OUTWARDLY THEREFROM; A HORIZONTALLY EXTENDING SLIDE ON SAID SUPPORT; A CARRIAGE SLIDABLY MOUNTED ON SAID SLIDE; CRUSH DRESSING MEANS MOUNTED ON SAID CARRIAGE FOR ENGAGING SAID WORK WHEEL; MEANS FOR MOVING SAID CARRIAGE TOWARDS AND AWAY FROM SAID WORK WHEEL; CO-OPERATING FIRST AND SECOND MOTOR MEANS FOR RESPECTIVELY EFFECTING ROTATION OF SAID WORK WHEEL AT A HIGH SPEED AND A MUCH LOWER SPEED; AND SWITCH MEANS FOR PREVENTING ENERGIZATION OF SAID FIRST MOTOR MEANS WHEN SAID CRUSH DRESSING MEANS APPROACH SAID WORK WHEEL AND FOR SELECTIVELY ENERGIZING AND DE-ENERGIZING SAID FIRST AND SECOND MOTOR MEANS, SAID SWITCH MEANS COMPRISING AT LEAST A CONTROL SWITCH, AND CONTROL SWITCH OPERATING MEANS INCLUDING A PROJECTION ON SAID CARRIAGE, MOVABLE MEANS HAVING A PORTION EXTENDING INTO THE PATH OF SAID PROJECTION AND HAVING A PORTION FOR ACTUATING SAID CONTROL SWITCH, SPRING MEANS FOR OPPOSING ACTUATION OF SAID CONTROL SWITCH AND FOR BIASING SAID MOVABLE MEANS TO PLACE THE FIRST MENTIONED PORTION THEREOF INTO THE PATH OF SAID PROJECTION SAID PROJECTION AND SAID MOVABLE MEANS BEING ARRANGED TO MAINTAIN SAID CONTROL SWITCH IN A POSITION TO PREVENT ENERGIZATION OF SAID FIRST MOTOR MEANS UNTIL SAID CARRIAGE HAS BEEN RETRACTED TO MOVE SAID CRUSHING MEANS A GIVEN DISTANCE AWAY FROM SAID WORK WHEEL, WHICH DISTANCE IS LESS THAN THE DISTANCE SAID CARRIAGE CAN MOVE ON SAID SLIDE, SAID FIRST MOTOR MEANS HAVING A SHAFT AND MEANS ON SAID SHAFT FOR EFFECTING ROTATION OF SAID WORK WHEEL, A SPEED REDUCER DRIVEN BY SAID SECOND MOTOR MEANS, AND AN OVER-RIDE CLUTCH DRIVEN BY SAID SPEED REDUCER AND CONNECTION FOR DRIVING SAID SHAFT AT A LOW SPEED.