US2130823A

US2130823A - Grinding machine

Info

Publication number: US2130823A
Application number: US144668A
Authority: US
Inventors: John C Wilson
Original assignee: Safety Grinding Wheel & Machin
Current assignee: Safety Grinding Wheel & Machin; Safety Grinding Wheel & Machine Co
Priority date: 1937-05-25
Filing date: 1937-05-25
Publication date: 1938-09-20
Anticipated expiration: 1955-09-20

Description

Sept. 20, 1938. J, c WILSON 2,130,823

GRINDING MACHINE Filed May 25, 1937 4 Sheets-Sheet 1 INVENTOR ATTORNEYS Sept. 20, 1938. J. 0. WILSON GRINDING MACHINE Filed May 25, 1937 4 Sheets-Sheet 3 (Ittornegs Sept. 20, 1938;

J. C. WILSON GRINDING MACHINE Filed May 25, 1937 lag 4 Sheets-Sheet 4 Cttorncgs Patented Sept. 20, 1938 UNITED STATES PATENT OFFIQE GRINDING MACHINE Application May 25, 1937, Serial No. 144,668

3 Claims.

\ This invention relates to improvements in grinding machines.

An object of the invention is to provide improved means for imparting a uniform and correct peripheral speed to the grinding wheel as the wheel wears.

A further and more specific object of the invention is to provide improved means for impart ing a uniform speed to the grinding wheel of a character which will avoid the necessity of changing the relation of the wheel spindle and the motor shaft.

In the accompanying drawings:

Fig. 1 is an end view of a grinding machine embodying the improvements.

Fig. 2 is a section on the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary top plan view with some of the parts shown in transverse section.

Fig. 4 is an enlarged end elevation of some of the parts shown in Fig. l but in a different working position.

Fig. 5 is a View partly in section and partly in end elevation of some of the parts shown in Fig. 1.

Fig. 6 is a section on the line 6-6 of Fig. 5.

Fig. 7 is an enlarged fragmentary section on the line 7-'l of Fig. 3.

Fig. 8 is an enlarged fragmentary section on the line 8-8 of Fig. 3.

Referring to the drawings, I represents a supporting base which has bolted thereon a hood 2 for the grinding wheel 3, one side 2 of the hood being hinged so as to be swung laterally in a well known way to permit installation of the grinding wheel. The grinding wheel is removably mounted upon one end of a spindle 4 which is journaled in suitable bearings 5 on the upper side of the base. The front of the hood 2 is provided with an opening to expose the grinding wheel and is equipped inthe usual way with a curved guard 6 which is 4.0 slidably mounted in channel members I secured to the hood. This guard 6 is manually adjustable toward the wheel by mechanism hereinafter described and acts as a gauge to determine the adjustment of the variable speed devices to provide uniform and correct peripheral speed for the grinding wheel. A pair of bolts 8 are passed through the upper portions of the channel member l and the guard 6, with nuts 9 on the inner ends of the bolts, and the bolts have hand knobs It] on their forward ends with springs ll interposed between the hand knobs and the channel members which bolts act to yieldably hold the guard in its adjusted positions.

The guard 6 is moved toward the grinding wheel 55; as the wheel wears by the following devices: A

hand wheel 12 is located on the forward side of the machine and is connected with a shaft l3 which has on its inner end a miter gear to (Fig. 3) meshing with a second miter gear on one end of a horizontal shaft It. The other end of the shaft 56 is provided with a sprocket wheel H which drives another sprocket wheel 58 through the medium of a sprocket chain E 9. The sprocket wheel 18 is fixed on the intermediate portion of a short shaft 20. The shaft 2?) has near one end thereof a spur gear pinion 2! (Fig. 4). The spur gear 2! is meshed with a gear segment 22 fast to a shaft 23 to which is connected a crank arm 2%. The crank arm 24- is pivotally connected to one end of a rocker beam 25 through the medium of a link 26. The rocker beam is pivotally carried by a bracket 21 on the hood and the other end of the rocker beam is connected to the rear portion of the upper end of the guard 6. The guard E has an car 28 formed with a slot 29 through which extends a pin 30 which is fast to the rocker beam. By this arrangement it will be seen that when the hand wheel is turned in one direction the guard 6 may be adjusted toward the grinding wheel, this adjustment being made at intervals as the wheel wears. In Fig. 4 the guard 6 is shown in full lines in the position it assumes for a new wheel and in dot-dash lines in the position assumed after the wheel has worn out.

Provision is made for varying the speed of the wheel as it wears, the speed of the spindle of the wheel being gradually increased as the wheel Wears away, the guard 6 acting as a gauge to control the increased speed of the spindle. In order to avoid the necessity of changing the relation of the motor shaft and the grinding wheel spindle to secure variable speed of the wheel spindle I make use of sheaves which are capable of having the effective radii of the belt contacts changed, one set of these sheaves being located on the motor shaft and another set on an intermediate or jack shaft, which in turn has a driv ing connection with the wheel spindle. Each sheave of a set is formed of two companion mem 'bers, a stationary member and a movable member, having opposed tapered surfaces to form an outwardly tapered groove.

The motor which drives the wheel spindle is indicated at 3! and its shaft at 32 (Fig. 6 only). The jack shaft which is driven from the motor shaft 32 is indicated at 33. Referring first to the sheaves which are mounted upon the motor shaft (Figs. 5 and 6), 34 represents a hub which is secured to the motor shaft by set screws one of which, 35, is shown. Rotatably connected with the hub 34 are a plurality of fixed sheave members 36 which have tubular extensions 31.

These fixed sheave members are fast to the hub 34 by a long key 38. Slidably mounted upon the tubular extensions 31 are movable companion sheave members 39, each one of which has a plurality of lugs 49 which extend through openlngs M in its companion fixed sheave member and abut against the next adjacent movable sheave member and so on throughout the series so as to hold the sheave members properly spaced. The final lug 40 at the right of the sheave assembly abuts against a final movable sheave member 42 and all of the movable sheave members are connected together by a plurality of long screws 42a. The movable sheave member 42 has an extended hub 44 which is slidably mounted in a bore $5 in one end of the hub 34. The series of movable sheave members are moved to and from their companion sheave members by a screw 46 which is rotated by connections which are operated when the guard 6 is adjusted. This screw has thereon a nut ll which is held from turning by a strap '58, which is fast to an internally threaded collar 49 which is screwed on the nut 37. The nut i? has fast thereto an inner ball race 50 and the movable sheave member 42 has fast thereto an outer ball race 5i, ball bearings 52 being interposed between the races; the extended hub M of the member 42 having a shoulder as-shown against which the race 5! bears. The inner end of the screw has an enlarged head 53 and an enlarged boss 54. An inner ball race 55 is fixed to the boss 54 and an outer ball race 56 is fixed to the bore of the hub 3 with ball bearings 5i interposed. As a result of this construction when the screw is turned in either direction all the movable sheave members will be simultaneously moved to or from their companion stationary sheave members to a like extent so as to increase or diminish the effective radii of the belt contacts, the belts being indicated at 58 and being of the V-type. In Fig. 6 the sheave members on the motor shaft are shown adjusted to permit the belt contacts to be at the lowest possible radii. When the motor shaft and the sheave members rotate they will revolve about the nut 67 and boss 54 of the screw, the ball bearings being interposed to reduce friction.

On the jack shaft 33 is a similar arrangement of sheave members and associated parts indicated by the same reference characters as the mechanism on the motor shaft with the addition of prime marks and which need not be described in detail with the exception to state that the screw, indicated at 46 is of opposite hand from the screw 46 so that when the screw 36 is adjusted to separate the companion sheave members to decrease the effective radii of the belt contacts the companion sheave members on the shaft 33 will be moved closer together to increase the effective radii of the belt contacts. The nut 41 on the screw 46 is held from turning by a strap 59 which is fastened to the nut 47 in the same manner described in connection with the device on the motor shaft.

The free ends of each of the'straps 48 and 59 are forked and straddle a reduced portion of a rod 6b which is fixed to the base.

These forked ends of the straps are held on the reduced portion of the rod by a collar Bi and a coil spring 62 is interposed between the straps and the shoulder formed by a reduced portion to prevent vibration of the straps.

The

screws

46 and 46 are operated simultaneously, one to increase the effective radii for the belt contacts on the motor shaft and the other to decrease those radii on the jack shaft, as the grinding wheel wears. To that end the screw 46 has attached thereto a sprocket wheel 63 and the screw 46 has fixed thereto a sprocket wheel E53. Passing about these sprocket wheels is a sprocket chain 64 which also passes about a sprocket wheel 65 fast to the shaft 20 which has been previously described as being operated by the hand wheel l2. This sprocket chain 64 also passes about an idler and tension sprocket wheel 65 and another idler sprocket Wheel 61. Each of the sprocket wheels 66 and 6'! is rotatably mounted upon opposite ends of a double armed lever 68 which is pivotally and rockably mounted upon the shaft 20 and a spring 69 fast to one arm of this lever exerts a tension to draw it downwardly to take up any slack in the sprocket chain fi l. As a result of this construction when the hand wheel I2 is operated to move the guard 6 toward the grinding wheel as it wears it will act to adjust the movable sheave members with relation to their stationary companion members to increase the effective radii of the belt contacts of the sheave members on the motor shaft and decrease the effective radii of the belt contacts of the sheave members on the jack shaft to thereby increase the speed of the grinding wheel spindle which is connected with the jack shaft in the following manner: The jack shaft has thereon a pulley H! with a series of grooves to receive a series of belts II which pass about a series of grooves in a .plain pulley F2 on the wheel spindle 4 (Figs. 3 and 4).

Provision is made for initially adjusting the supports for the jack shaft and for the motor shaft in order to bring the proper tension upon the belts. The jack shaft is supported in bearings 73 in the casting M which is slidably mounted upon a central bar '75 and end bars 16 (Figs. 3 and '7). The bar 15 has fixed thereto a collar Tl which has an exteriorly threaded extension 18. A nut '59 is threaded on this extension and is adapted to bear against the boss 8i? on casting M whereby the casting M and the jack shaft may be adjusted in order to tighten the belts between the jack shaft and the wheel spindle. The motor 3| is hingeably supported at one point on the rod 60 and has pivoted to another point thereof as at 8| an adjusting screw 82 (Figs. 1, 3 and 8), this adjusting screw passing through the bifurcated ear 83 on the casting 14 which supports the jack shaft. A nut 84 is threaded on the screw 82 and bears against the hollow block 85 which is loosely mounted on the screw and is rockably supported on conical shaped pins 86 which are threaded in the members of the ear 83 on the casting M. There is threaded on the screw below the hollow block another nut 81. In order to increase the tension on the belts between the motor shaft and the jack shaft the nut 84 is turned upwardly on the screw so as to let the motor and its shaft drop by gravity. After this adjustment is made the nut S! is turned up against the lower end of the hollow block to prevent the motor and its shaft from climbing in starting.

It will be understood that after a grinding wheel has become worn out it is impossible to insert a new wheel until all of the parts have been restored to initial position. This is accomplished by rotating the hand wheel 12 in the reverse direction Which acts to not only restore the guard 6 to the full line position shown in Fig. 4

but also acts to move the screws 46 and 46' in the reverse direction so as to separate the companion sheave members on the motor shaft 32 and bring together the companion sheave members on the jack 33 to reduce the speed of the grinding wheel spindle.

One of the advantages of this construction is the employment of a jack shaft, this jack shaft arrangement being peculiarly adaptable to an arrangement in which a grinding wheel is located upon each end of the spindle, which arrangement, however, is not shown in the present instance. It is essential that the mechanism for varying the sheave members of the driving pulleys be located on the end of the shafts (either the motor shaft or the jack shaft) so that it will be apparent that if no jack shaft is employed it would be impossible to position a set of the variable driving sheaves directly upon the wheel spindle where a grinding wheel was located on each end of the spindle. It will be understood that the sizes of the pulleys upon the motor shaft and upon the jack shaft are the same,but that the sizes of the plain pulley upon the jack shaft and upon the wheel spindle may vary depending upon conditions of design.

Having thus described my invention, I claim:

1. In a grinding machine, a spindle, a grinding wheel mounted on said spindle, a guard for said wheel, a motor shaft, driving connections between said shaft and spindle comprising variable driving and driven sheaves interposed therebetween each consisting of relatively movable companion members having opposed outwardly tapered faces, a belt passing about said sheaves, manually-operated devices for adjusting said guard toward said Wheel as the wheel wears, said devices comprising a pair of sprocket wheels, a chain for driving one of said sprocket wheels from the other, a pinion connected to rotate with said driven sprocket wheel, a segmental rack meshed with said pinion, a pivoted rocker beam having one end connected with said guard, and means including a pivoted link for connecting said segmental rack with the other end of said rocker beam.

2. In a grinding machine, a spindle, a grinding wheel mounted on said spindle, a guard for said wheel, a motor shaft, driving connections between said shaft and spindle comprising variable driving and driven sheaves interposed therebetween each consisting of relatively movable companion members having opposed outwardly tapered faces, a belt passing about said sheaves, manually-operated devices for adjusting said guard toward said wheel as the wheel wears, means operated by said manually-operated devices to simultaneously adjust the distance between the companion members of said sheaves to increase the effective radius of the belt contact of the driving sheave and decrease the efiective radius of the belt contact of the driven sheave, said means comprising a sprocket wheel operated by said manually-operated devices, a sprocket wheel associated with each of said sheaves, and a chain passing about said sprocket wheels.

3. In a grinding machine, a spindle, a grinding wheel mounted on said spindle, a guard for said wheel, a motor shaft, driving connections between said shaft and spindle comprising variable driving and driven sheaves interposed therebetween each consisting of relatively movable companion members having opposed outwardly tapered faces, a belt passing about said sheaves, manually-operated devices for adjusting said guard toward said wheel as the wheel wears, means operated by said manually-operated devices to simultaneously adjust the distance between the companion members of said sheaves to increase the effective radius of the belt contact of the driving sheave and decrease the effective radius of the belt con- 7 tact of the driven sheave, said means comprising a sprocket wheel operated by said manually-operated devices, a sprocket wheel associated with each of said sheaves, and a chain passing about said sprocket wheel, said means also including an adjusting screw associated with each sheave, one of a right-hand and the other of a left-hand thread, said sheaves being connected with said sprocket wheels.

JOHN C. WILSON.