US2286293A - Grinding machine - Google Patents

Description

June 16, 1942. A, w, MALL 1 2,286,293

GRINDING MACHINE Filed March-4, 1940 3 Sheets-Sheet 1 5 Fiel INVENTIII'R QM WM 772 i? BY flaw/m2; ATTORNEY June 1 1942. A. w. MALL 2,286,293

GRINDING MACHINE Filed March 4, 1940 3 Sheets-Sheet 2 Fie.2

/6 i /6 /4 v l4 INVENTIIIR" W Km ATTORNEY June 16, 1942. w, MALL 2,286,293

GRINDING MACHINE Filed March 4, 1940 3 Sheets-Sheet 3 512%! I IIAI,

JNVENTUR 4M. Maw." 772412 a&% Jx2z;

ATTORNEY applied to the work as it progresses.

Patented June 16, 1942 UNITED stares earaur OFFICE GRINDING MACHINE Arthur William Mall, Flossmoor, Ill.

Application March 4, 1940, Serial No. 322,214

6 Claims.

adaptable to the needs of the grinding industry.

A specific object is to reduce the initial cost of the machine by eliminating frame work for supporting the machine. In my machine the motor itself serves as the basic frame. Brackets are formed integrally with the end housings of the motor and the wheeled supports are secured to the brackets.

By providing two universally pivotal casters.

at the rear of the machine and one at the front in combination with the provision of a low center gravity of the entire machine, I obtain the type of machine which is readily manipulable.

When the operator is grinding terrazzo, for example, his only concern is to keep the grinder Consequently it is desirable to move the grinding spindle about at will. In the operation of my machine any slight pull on the flexible shaft by the operator will cause the machine to tag along in any direction with the least of effort. The low center of gravity allows the machine to be .jerked about without any fear of its being tipped over.

Along with the combination of features which assure an easily manipulable machine, I have provided variable pitched motor and countershaft pulleys for changing the speeds of the grinding spindle whereby the machine may be adapted toa number of different kinds of grinding operations. To facilitate changing or loosening and tightening of the pulley belt, I have provided a quickly operable eccentric device.

The primary object of my invention is to provide a grinding machine which incorporates a combination of features which unite to make the machine readily adaptable to industrial needs.

One of the specific objects is to provide a simple and expedient device for loosening and tightening the pulley belt.

Another object is to provide the machine with a low center of gravity to prevent tipping.

Another object is to provide the machine with universally pivotal wheeled supports so that the machine will tag along after the operator.

Still another object is to provide a bracket member which serves as a wrench for changing grinding wheels and which also serves as a supporting hook around which the electrical cord may be wound when the machine is not in use.

Other objects and advantages will be apparent upon reading the following specification and the accompanying drawings. forming a part of the specification, in which:

.Fig. -1 is a side elevation of the machine;

Fig. 2 is a front view;

Fig. 3 is a fragmentarysectional view of the countershaft housing; and

Fig. 4 is a sectional view taken on line 4-4 of Fig. 3.

In the preferred embodiment of my invention I have shown a motor I of H. P. capacity,

capable of 2 H. P. momentary overload capacity.

Avariable pitch motorpulley 2 drives the countershaft pulley 3 by means of belt 28. I have provided a flexible shaft take-.ofi 4 from the countershaft pulley and a grinding wheel spindle .5 driven by the fiexibleshaft 4. Suitable guards 6 and 1 are provided for each pulley.

The motor I is .provided at each end with end bells 8 and 9. A boss I0 is formed integrally with the end bell 8. A bracket H is secured to the boss [0 by being bolted thereto. A universally pivotal caster I2 is fastened to the forward end of the bracket ll. Support arms l3 are formed integrally with the end bell 9 and are provided with hubs M to which are mounted a pair of universally pivotal casters IS.

The arms [3 are spaced well apart providing .a sufficient area of support to assure against the machine tipping over sideways.

The motor I which forms the major portion of the weight of the :entire machine is disposed centrally between the three casters to assure a Well balanced machine. The center of gravity of the machine is located at a .point centrally between the three casters and closely adjacent the floor level. Thus it can be seen that tipping of the machine is rarely possible. This is an important feature of the invention as the machine is of the type that is dragged about somewhat carelessly by the operator.

By using three casters instead of four a tricornered support for the machine is obtained. This assures that the "machine is more readily adaptable to tag along after the operator regardless of which direction he pulls on the flexible shaft. The casters are universally pivotal so as to cause the machine to readily follow the direction of the operators pull.

The support arms l3 have bosses 16 formed integrally therewith. These bosses are bored to receive the ends of a U-shaped handle I! which is used to push the machine about from one grinding operation to another. In the upper region of the handle H a spindle wrench I8 is secured thereto, thereby assuring that a wrench will always be available for unloosening the spindle nut when it is desired to change grinding wheels. A hook I9 is also secured to the handle H in the upper region thereof and serves as a means for supporting the spindle when not in use.

When the machine is not in use the electrical cord 20 is wrapped about the handle I! and supported by the wrench l8 and the hook IS. A tool box 2| is supported immediately above the motor by means of the brackets 22, 23, and 24. The tool box has upwardly extending and inwardly converging side walls 25.

A boss 26 is formed integrally with the motor end bell 8 and supports the upright 21.

Referring particularly to Figs. 3 and 4 I have provided a novel means for loosening and tightening the pulley belt 28. Formed integrally with the upright 21 at the upper end thereof is a cylindrical ring member generally referred to as 30. The countershaft 3| to which the countershaft pulley 3 is secured, is journalled in bearings 32 and 33 within the countershaft housing 34. The bearings 32 and 33 are spaced by the sleeve 46 and a cap nut 41 retains the bearings 32 and 33 in position. A drive nut 48 is adapted to receive the threaded tip of the flexible drive core (not shown). Secured to the countershaft housing 34 preferably by welding thereto is an eccentric annular flange 35 rotatably journaled in a cylindrical recession 36 Within the ring member 30. The inner face of the flange 35 abuts the annular shoulder 31. A second cylindrical recession 38 in the ring 30 is adapted to receive the head 39 of a bolt 40. The head 39 abuts the annular shoulder 4|. The bolt 43 is journaled through a bore 42 in the eccentric flange 35. A reduced region in the ring 30 forms a collar 60 defined between the shoulders 31 and 4|. The bolt 40 is milled at 43 so as to fit snugly against the inner surface of the collar 60. Thus when the nut 44 is loosened or tightened the bolt 49 will not rotate along with the nut.

Thus it can be seen that when it is desired to change the pulley belt 28 from one groove to another or when it is desired to loosen or tighten the belt 28, the nut 44 is loosened. The eccentric flange 35 is then free to be rotated within the cylindrical recession 36. The operator grasps the countershaft housing 34, to which the eccentric flange 35 is welded, and turns it so as to rotate the eccentric flange 35. It can be seen that this changes the position of the countershaft pulley 3 relative to the motor pulley 2, either increasing or decreasing the distance between the axes of the two pulleys (whichever is desired). When the desired loosening or tightening of the belt 23 is obtained, the countershaft housing 34 and eccentric flange 35 are manually held in the desired position until the nut 44 is tightened again. When the nut 44 is tightened, this locks the inner face of the eccentric flange 35 against the shoulder 31 thereby retaining the countershaft pulley 3 in its selected adjusted position.

Referring to Fig. 2 a switch 50 for starting and shutting off the motor I is secured to the motor housing and has an electrical conductor cable 20 with .a plug-in Having thus described my invention what I claim is:

1. A grinding machine comprising movable supporting means, a grinding tool, a motor, a motor shaft, an upright secured to the motor, a hub portion at the upper end of the upright, a bore in said hub portion, a countershaft housing journaled in the bore, a countershaft within the housing and operatively connected to the grinding tool, a pulley secured to the countershaft, a second pulley secured to the motor shaft, a belt trained about the pulleys, means for adjusting the tension of the belt relative to the pulleys, said means including a ring rotatably journaled in the hub bore, an eccentric bore in said ring, said countershaft housing being journaled in the eccentric bore and secured to the ring so as to be rotatable therewith, whereby the adjustment of the belt tension is obtained by manually rotating the countershaft housing and the eccentrically bored ring until the desired tension is obtained, and means for maintaining the adjusted tension of the belt, said means including a bolt extending through the eccentric ring for clamping the ring in a fixed position within the bore of the upright.

2. A grinding machine as defined in claim 1 wherein there is a flanged region within the hub bore against which the head of the bolt abuts so so as to clamp the ring in a fixed position within the hub bore of the upright.

3. A countershaft pulley drive device comprising spaced pulleys, a support member for one of the pulleys, a belt trained about the pulleys, a pulley shaft extending through the support member and secured to the pulley for rotation therewith, means for adjusting the tension of the belt relative to the pulleys, said means including an eccentrically bored ring rotatably mounted in said support member, said pulley shaft extending through the eccentric bore, a bolt hole, an annular shoulder in said support member, whereby the bolt may be tightened against said shoulder.

4. A countershaft pulley drive apparatus, comprising spaced pulleys, a support member for one of the pulleys, a belt trained about the pulleys, a

pulley shaft secured to the pulley for rotation V therewith, means for adjusting the tension of the belt relative to the pulleys, said means including a ring rotatably mounted in the support member, an eccentric bore in said ring, said pulley shaft extending through the eccentric bore, and means for maintaining the adjusted tension of the belt, said last means including a bolt extending through the eccentric ring for clamping the ring in a fixed position relative to the support member.

5. A countershaft pulley drive apparatus, comprising spaced pulleys, a support member for one of the pulleys, a belt trained about the pulleys, a pulley shaft secured to the pulley for rotation therewith, means for adjusting the tension of the belt relative to the pulleys, said means including a ring rotatably mounted in the support member, an eccentric bore in said ring, said pulley shaft extendingthrough the eccentric bore, and means for maintaining the adjusted tension of the belt, said last means including a bolt extending through the ring, and an annular shoulder in the support member, said bolt being adapted to clamp the ring against the annular shoulder.

6. A countershaft pulley drive apparatus, comprising spaced pulleys, a support member for one of the pulleys, a belt trained about the pulleys, a

for maintaining the adjusted tension of the belt, said last means including a clamping member having engagement with the ring and the annular shoulder for urging the ring against the shoulder to prevent rotation of the ring relative to the shoulder.

ARTHUR WILLIAM MALL.

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