US2298228A - Terrazzo grinder - Google Patents

Description

Oct. 6, 1942. P NP 2,298,228

TEBRAZZO GRINDER Filed Ju1 2o, 1940 -4 sheets-sheet 1 Harold J. Pond and Carl 0. Larson Oct.'6, 1942. H. J. POND EI'AL 2,298,228

TERRAZZO GRINDER Filed July 20, 1940 4 Sheets-Sheet 2 e9 61. P1. g} 47 m &

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TERRAZZO GRINDER Fiied July 20, 1940 4 Shepts-Shet 4 o u M "Harold J. Pond and. Cad O Larson Patented Oct. 6, 1942 TERRAZZO GRINDER Harold J. Pond and Carl 0. Larson, Minneapolis, Minn., assignors to Advance Machine Company,

Inc., Minneapolis, Minn.,

Minnesota a corporation of Application July 20, 1940, Serial No. 346,623

10 Claims.

Our invention relates to portable tools and particularly to motor driven grinders adapted to be used for grinding vertical surfaces of terrazzo and similar materials used in building construction.

An object of the invention resides in providing a grinder capable of covering an extended vertical surface with minimum repositioning of the entire grinder.

Another object of the invention resides in providing a grinder capable of being used with angularly disposed surfaces.

An object of the invention resides in providing a grinder which will not require accurate setting of the same with reference to the surface to be ground.

A still further object of the invention resides in providing a grinder capable of being easily and. quickly transported.

A feature of the invention resides in providing a portable grinder capable of being easily and quickly brought up to the surface to be ground and moved along the same.

An object of the invention resides in providing a portable grinder which is easy to manipulate, and in which the weight of certain of the parts is counter balanced by the weight of the motor.

A still further object of the invention resides in providing a base having an upright carried thereby and pivotally supporting a motor carrying a pair of jointed arms and in one of which the grinding wheel is rotatably supported.

An object of the invention resides in providing pivot means between the motor and upright permitting the motor to swing about two axes at right angles, one of said axes being substantially horizontal.

Another object of the invention resides in supporting the arms for movement in planes shiftable out of parallelism.

An object of the invention resides in providing pivot means between the two arms whereby the arms may swing about two aXes substantially at right angles to one another.

Other objects of the invention reside in the] novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/ or described.

In the drawings:

Fig. 1 is a plan view of a portable tool illustrating an embodiment of our invention.

2 is an end elevational view of the structure shown in Fig. 1.

Fig. 3 is a side elevational view of the structure shown in Figs. 1 and 2.

Fig. 4 is a cross sectional View taken on line 4-4 of Fig. 2 and drawn to a greater scale.

Fig. 5 is a view similar to Fig. 4 taken on line 5-5 of Fig. 1.

Fig. 6 is a cross sectional view taken on line 66 of Fig. 1 and drawn to the same scale as Figs. 4 and 5.

Fig. 7 is a fragmentary plan View taken on line 'l'! of Fig. 2.

Fig. 8 is a view similar to Fig. 3 showing the tool used for grinding under cut risers of stairs.

Fig. 9 is a view similar to Fig. 3 showing the tool arranged to cut beveled coves.

Fig. 10 is a fragmentary elevational view taken on line llll0 of Fig. 3.

The invention comprises a base it which may be constructed from sheet metal or a casting, or which may be constructed in any other suitable manner. This base is triangular in shape, as best shown in Fig. l, and is supported at one of the corners thereof by means of a caster wheel ll which is mounted to swivel on a fork [2 in the customary manner. At the other corners of the base the same is supported on wheels l3 and M which are mounted in identically the same mariner. For this reason only the method of mounting the wheel [3 will be described in detail. This wheel is carried on a pintle l5 which is journaled in a fork I6. Fork It has a stud I! extending upwardly therefrom which is rotatably mounted in a bearing formed in the base IE! by drilling the same, as indicated at H8. The fork i6 is of larger dimensions than the stud I! so that the same provides a shoulder on which the base l0 rests. The stud IT projects upwardly beyond the base l9 and is formed in its projecting end with a vertically extending slot [9. In this slot is disposed a handle 21 which is pivoted thereto by means of a pin 22 extending jointly through said stud and handle. The handle may be swung upwardly on the pin 22 or moved to a horizontal position, as shown in Fig. '7. When in a horizontal position the handle 2| may be moved from the full line position shown in said figure to the dotted line position or vice versa. The handle 2| is held in either of its two positions shown in Fig. '7 by means of spaced lugs 23 and 24 between which the handle may drop. When the handle is between the lugs 23 the wheel 13 is held in a position parallel with the forward edge 25 of the frame l8 and when said handle is between the lugs 24 said wheels are at right angles to said edge.

Immediately above the caster wheel H is provided an upright 26 preferably constructed as a casting which has a foot 21 formed thereon and which is bolted to the base II) by means of cap screws 28. The upright 26 is formed with a goose neck 29 which is disposed above the intermediate portion of the base I0.

The invention utilizes an electric motor 3| provided with a core structure 32 and having end bells 33 and 34 attached thereto. In these end bells is journaled a shaft 35 which is attached to the rotor of the motor. The core structure 32 of the motor has attached to it a number of feet 36 which normally serve as a base for the motor. These feet have attached to them two spaced U-shaped brackets 31 and 38 which are bolted to said feet by means of cap screws 39. The two brackets 31 and 38 have bearings 4| formed thereon which journal a shaft 42. A hanger 43, attached to the goose neck 29, is provided with a bore 44 which receives the shaft 42, said hanger being disposed between the bearings 4|. By means of this construction the motor 3| is mounted for swinging movement about the axis of the shaft 42 which is substantially parallel to the axis of the motor shaft 35 and which is eccentric relative thereto. The hanger 43 is constructed with an ear 45 which overlies the end 46 of the goose neck 29. A bolt 41 disposed with its axis in a horizontal position extends through the ear 45 and through the end 46 of the goose neck 29 and provides a pivot having a horizontal axis whereby the entire motor and hanger may be moved in a vertical plane. A look bolt 48 also extends through the ear 46 and through a slot 49 in the end 46 of the goose neck 29. By means of this lock bolt the motor 3| and hanger 43 may be held in angularly adjusted position.

The invention further embodies two jointed arms and 52, the arm 5| being attached to the motor BI and the arm 52 carrying a suitable tool holder 53. The arm 5| is attached to the motor 3| in the following manner: Secured on the end bell 33 by any suitable means, not shown, is a flange 54 through which the motor shaft extends. The arm 5| is constructed in two parts 55 and 56 which have channel-shaped portions 51 at the outermost edges and which have web portions 58 therebetween. The web portions 58 are bolted together at intervals by means of bolts 59. flange 6| which is bolted to the flange 54 by means of cap screws 62. This flange is so arranged with reference to the flange 54 that the axis of the shaft 42 substantially intersects the center line of the arm 5|. By means of this construction the arm 5| is rigidly attached to the motor 3|. The end of the part 55, of arm 5|, opposite the flange BI, is constructed to provide a case in which is disposed a pulley attached to the shaft 35.

The two arms 5| and 52 are connected together by means of a construction, best shown in Fig. 5. The part 56 of arm 5| has formed on it a flange 63-, while the corresponding portion of the part 56 is provided with a cap 64. These two parts form a case having a compartment 65 within the same in which is disposed a pulley 66. Pulley 66, is mounted on a shaft 61 which is journaled at one end in a ball bearing 68 mounted in the cap 64. A cover 69 covers the end of the shaft 51'. Rotatably mounted in a socket H in the flange 63 is a head 12. This head carries a ball bearing 13 which journals the other end of the shaft 61. The ball bearing 13 fits against a shoulder 14 in the head 12, while the ball bear- The part 56 is provided at one end with a a ing 68 similarly fits against a shoulder 15 in the cap 64. The two ball bearings are urged toward one another by means of a nut 16 screwed on one end of the shaft 61 and one member 11 of a universal joint 18 screwed on the other end of the said shaft. By means of this construction the head 12 is rotatably held within socket 1| and against the flange 63.

The arm 52 is constructed in identically the same manner as the arm 5| being formed with two parts BI and 82, bolted together in the same manner. The part 82 is constructed with a sleeve 63 projecting outwardly therefrom which is disposed opposite the head 12. Head 12 is provided with two ears 84 projecting outwardly therefrom which overlie the sleeve 63. These ears have screwed in them conical pivots 85 which are seated in jewels 86 mounted in the sleeve 83. The pivots 85 are held in adjusted position by means of set screws also screwed in the ears 84. By means of these pivots the arm 52 is guided for swinging movement about an axis through the said two pivots which is parallel to the plane of movement of the arm 5| about shaft 42 and at right angles to the axis of the shaft 61.

The part 8| of arm 52, opposite the sleeve 83, is constructed with a hub 81 which is provided with two ball bearings 88 and 89. These ball bearings journal a shaft 9| which has secured to the end of it the other member 92 of the universal joint 18. This universal joint includes a ring 93 of flexible material such as rubber impregnated fabric, leather or the like, which is bolted to the two members at alternately spaced locations by means of cap screws 94. This universal joint forms a driving connection between the shafts 61 and 9| which permits the arm 52 to swing about the pivots 85 to a limited extent.

The tool holder 53 of the invention is attached to the end of the arm 52 and is shown in detail in Fig. 4. This tool holder is constructed and mounted as follows: At the end of the part 8| of arm 52 is provided a boss 96 which is bored as indicated at 91 to receive the end of a tubular housing 98. The tubular housing 98 has a flange 99 formed thereon which is attached to the boss 96 by means of cap screws IOI. The tubular housing 98 has mounted in it at the ends thereof ball bearings I02 and I03 which rotatably support a shaft I04. The two bearings I02 and I03 are held in position upon the shaft I04 by means of a nut I05 screwed on the outer end of the shaft and by means of spacer sleeves I96 and I01. Adjacent the sleeve I91 is a pulley I08 which is urged against the sleeve I01 by means of another nut I09 screwed on the inner end of said shaft. The pulley I08 is disposed in a compartment I38 formed at the end of the arm 52 by means of the boss 96 and a cap I31 formed on the part 82 of said arm. The bearing I03 floats in the end of the housing 88, while the bearing I02 is clamped in said housing by means of a shoulder III formed therein and a clamp ring II2 secured to the end of said housing by means of screws H3.

The nut I05 screwed on the end of shaft I94 is threaded as indicated at II 4 to receive one of the elements II5 of a universal joint H6. The other element II1 of this universal joint is attached to a short shaft II8 on which the tool to be operated by the device is mounted. In the instant invention the device is designed as a grinder and has a grinding wheel II9 mounted on the shaft II8. This wheel is held in position by means of a nut I2I screwed upon the end of the shaft H8. The two members H5 and H1 of the universal joint H6 are alternately secured to two rings I22 constructed of a flexible material similar to the ring 93 of the universal joint 18. This construction provides a flexible mounting for the wheel I I9 and, at the same time, serves to drive the said wheel from shaft I04. To take the end thrust imparted to the wheel H9 the shaft H8 is provided with a socket I23 which receives a spheroidal-shaped protuberance I24 formed on the forward end of the nut I65. This arrangement permits of angular operation of the shaft I I8 with respect to the shaft I04 and causes intersection of the axes of the two shafts to be maintained at the center of the socket I23.

The various shafts of the invention are driven in the following manner: As previously stated the shaft 35 of motor 3| has mounted on it a pulley 59 disposed within the interior of the case 48 in arm 5| at the locality of the flange 6!. This pulley carries a belt I25 which may be a V-belt, and which passes over the pulley 66, mounted on shaft 61, which was previously referred to. Shaft 61 drives shaft 9| through the universal joint 18. Mounted on the shaft 9| is a pulley I26 which is arranged to receive two V-belts I21. The two belts I21 also pass over the pulley I88, thereby affecting a drive between the shaft SI and I134. The shaft I94 drives the shaft H8 through the universal joint I I 6.

In order to permit of wet grinding of the terrazzo or other material to be ground, a reservoir I21, for water, is provided, which is mounted on a bracket I28 secured to the uppermost portion of the goose neck 29 of the upright 26. This reservoir has a hose I29 connected to it. A valve I 3| controls the flow of water through the said hose. The hose I29 is connected to the inlet side of a pump I 38 mounted on the arm 5|. This pump has a pulley I32 on it which is driven by a belt I33 from a pulley I34 on the end of the motor shaft 35 of motor 3|. The pump I30 has connected to it another hose I35 which follows along the two arms 5| and 52, and which 1 is connected to a hose fitting I36 screwed into the cap I31 formed on the part 82 of arm 52. The shaft I84 has a bore I39 in it and in which is mounted a tube I4I. This tube is flanged at its end and is held in position in the cap I31 by means of the hose fitting I36. This tube extends through a bore I43 in the nut I05 and up to the end of the protuberance I24 and communicates with a bore I42 in the shaft I I8. By means of this construction water is led under pressure directly to the shaft H8 from which is flows into the cavity I44 within the grinding wheel H9 whereby the water may be fed to the work as the grinding wheel operates. A revoluble guard I 45 rotatably mounted on the tubular housing 98 protects the grinding wheel H9 and also prevents any water which may leak out past the nut I and the shaft H8 from following back along the tool holder 53.

Attached to the arm 52 is a handle I46 by means of which the tool holder 53 may be manipulated.

The method of using the invention is as follows: Our improved portable tool when used as a grinder is particularly designed to grind verin Figs. 2 and 3 and the motor 3| adjusted through the two bolts 41 and 48 so that the arm 5| extends in a vertical plane. The entire grinder is then moved up to the work so that the grinding wheel H9 is within an inch or less of the surface to be ground. When the grinder is in such position the tool holder 53 is manipulated by means of the handle I46 which is secured to arm 52 and is moved in the plane of the surface to be ground both in a horizontal direction and in an up-and-down direction. The pivot formed by the shaft 42 permits of horizontal movement of the tool holder 53, while the pivot afforded by the rotation of head 12 in the bore 1| of arm 5| accommodates vertical movement of the said head. Due to the use of the universal joints 18 and I IS, the grinding wheel II 9 may be moved toward and from the surface to be ground and at the same time will readily adjust itself to the contour of the surface, thus compensating for variations in the positioning of the entire grinder with reference to the work to be ground. As a section of the surface to be ground is completed, the entire device is shifted in the direction of the extent of the surface to be ground, which is made possible by the arrangement of the wheels I3 and I4. The wheel II being a caster wheel, follows along with the wheels I3 and I 4, which lateral wheels serve to guide the device in the proper direction.

It frequently occurs that base boards are constructed at an angle as illustrated in Fig. 9. When the grinder is to be used for grinding such a surface the hanger 43 is tilted, as shown in Fig. 9, so that the grinding wheel faces in the proper direction. Where a cove is provided between the base and the floor, a wheel I41 is employed which has a rounded corner I48. This permits of grinding the cove at the same time the base is being ground.

In the surfacing of risers of stairs a platform is built which rests upon a number of the stairs and which is arranged to support the grinder as shown in Fig. 8. The platform is indicated by the reference numeral I 5| in Fig. 8. In this View the risers have been shown as inclining forwardly. When a riser of this type is to be surfaced the hanger 43 is adjusted as shown in Fig. 8, and a stone I52 such as illustrated is employed which gives sufficient clearance for the cap I31 of arm 52. In the grinding of these various surfaces the grinder is manipulated in identically the same manner as when used for grinding vertical surfaces.

It will be noted that the grinder, when the two arms are jackknifed, is less in width than in length. In transporting the machine to and from the work it hence becomes desirable to move the machine in a direction at right angles to the direction of travel of the machine during grinding. This may be easily and quickly accomplished by raising the handles 2| and swinging the studs I1 from the position shown in full lines in Fig. '7 to that shown in dotted lines in which the handle is held between the lugs 24. In the latter positions of the wheels, the grinder may be wheeled fcrwardly through narrow door openings and manipulated about in tight quarters. Adjustment of the machine toward and from the work may also be accomplished by swinging the wheels, as above noted, and after the machine has been brought into proper position with reference to the work, the wheels may be turned back into parallelism with the surface to be ground.

The advantages of our invention are manifest.

same becomes unnecessary.

The grinder is extremely compact and has a wide range of operation. With our invention considerable work may be done with one setting of the grinder so that frequent positioning of the The guide wheels of the grinder may be moved to-either of two positions whereby the grinder may be moved along the surface being ground, or moved toward and from the same. By means of the various pivots provided, the grinding wheel may be positioned to grind vertical surfaces and inclined surfaces such as are frequently found in building construction. By the use of the two universal joints the wheel can be made to adapt itself to the contour of the surface to be ground and at the same time inaccurate positioning of the machine with reference to the surface to be ground will have no effect upon the results.

The motor being used as a counter balance for the arms the weight of the grinder is held at a minimum and at the same time the tool is easy to operate and manipulate. With our invention the surfaces ground may be wet ground so as to avoid dust and to produce the results possible with wet grinding. Our improved portable tool can be constructed at a nominal expense and is sturdy in construction and serviceable in operation.

Changes in the specific form of our invention, as herein disclosed, may be made within the scope of what is claimed without departing from the spirit of our invention.

Having described our invention, what we claim as new and desire to protect by Letters Patent is:

1. In combination a base, an upright carried by the base, an electric motor having a shaft, pivot means between said motor and upright for guiding said motor for movement to cause the shaft thereof to swing in a substantial vertical plane, means for locking said motor from movement about said pivot means, a pair of jointed arms, one of said arms being connected to said motor, a movable tool holder carried by the other of said arms, and means supported by said arms and driven by the motor shaft for operating said tool holder.

2. In combination a base, an upright carried by the base, an electric motor having a shaft, pivot means between said motor and upright for guiding said motor for movement to cause the shaft thereof to swing in a substantially vertical plane, an arm attached to said motor, a second arm pivoted to said first arm about an axis parallel with the axis of said motor, a rotatable tool holder carried by said second arm and rotatable about an axis substantially parallel with the axis of said motor, and transmission means carried by said arms and driven by said motor shaft for operating said tool holder.

3. In combination a base, an upright carried by the base, an electric motor having a shaft, pivot means between said motor and upright for guiding said motor for movement to cause the shaft thereof to swing in a substantially vertical plane, an arm attached to said motor, pivot means for guiding said arm and motor for swinging movement about an axis substantially parallel with the axis of said motor shaft, arevoluble head pivoted to said arm about an axis parallel with the axis of said motor, said arm being movable in a plane at right angles to the axis of said motor, a second arm pivoted to said head about an axis parallel with the plane of movement of said first named arm and adapted to swing in a plane shiftable out of parallelism with the plane of movement of said first named arm, a rotatable tool holder mounted on said second named arm, and transmission means carried by said arms for driving said tool holder from said motor shaft.

4. In combination a base, an upright carried by the base, an electric motor having a shaft, pivot means between said motor and upright for guiding said motor for movement to cause the shaft thereof to swing in a substantially vertical plane, an arm attached to said motor, pivot means for guiding said arm and motor for swinging movement about an axis substantially parallel with the axis of said motor shaft, a second arm pivoted to the first arm for swinging movement in a plane substantially parallel to the plane of movement of the first arm, a universal joint between said arms for accommodating movement of said second arm in a plane out of parallelism with the plane of movement of the first arm, a tool holder, means for rotatably supporting said tool holder on said second arm for movement about an axis substantially parallel to the axis of said motor shaft, transmission means carried by said arms for driving said tool holder from said motor shaft, said transmission means including a universal joint concentrically arranged with respect to the universal joint between said arms.

5. In combination a power driven shaft adapted to be disposed in a substantially horizontal position, an arm pivoted for movement about an axis extending in the same direction as the axis of said shaft and adapted to swing in a plane at right angles to said shaft, a head pivoted to said arm and adapted to rotate in a plane parallel with the plane of movement of said arm, a second arm pivoted to said head and adapted to move about an axis parallel with the plane of movement of said first named arm and to rotate with said head in a plane shiftable out of parallelism with the plane of movement of said first named arm, a tool holder rotatable about an axis at right angles to the plane of movement of said second named arm, transmission means carried by said arms for driving said tool holder from said power driven shaft, said transmission means including a universal joint concentrically arranged with reference to the axis of said head.

6. In combination a power driven shaft adapted to be disposed in a substantially horizontal position, an arm pivoted for movement about an axis extending in the same direction as the axis of said shaft and adapted to swing in a plane at right angles to said shaft, a head pivoted to said arm and adapted to rotate in aplane parallel with the plane of movement of said arm, a second arm pivoted to said head and adapted to move about an axis parallel with the plane of movement of said first named arm and to rotate with said head in a plane shiftable out of parallelism with the plane of movement of said first named arm, a tool holder rotatable about an axis at right angles to the plane of movement of said second named arm, a pulley on said power driven shaft, a shaft carried by said first named arm and disposed substantially concentric with the axis of rotation of said head, a pulley on said second named shaft, a third shaft rotatably mounted in said second arm and disposed opposite said second named shaft, a universal joint between said second named shaft and third named shaft, a pulley carried by said tool holder, and a belt extending about the pulley on said tool holder and the pulley on the third named shaft.

7. In combination a base, an upright carried by the base, an electric motor having a frame and a shaft journaled in said frame, pivot means between said motor frame and upright for guiding said motor for movement to cause the shaft thereof to swing in a substantially vertical plane, an arm secured to said motor frame, pivot means for journaling said arm for swinging movement about an axis parallel with the axis of said motor shaft, a revoluble head pivoted to said arm about an axis parallel with the axis of said motor, a second arm pivoted to said head about an axis parallel with the plane of movement of said first named arm and adapted to swing in a plane shiftable out of parallelism with the plane of movement of said first named arm, a rotatable tool holder mounted on said second named arm, and transmission means carried by said arms and driving said tool holder from said motor shaft, said transmission means including a universal joint concentrically arranged With respect to the axis of said head.

8. In combination a base, an upright carried by the base, an electric motor having a shaft, a hanger pivoted to said upright about a substantially horizontal axis and adapted to swing in a substantially vertical plane, pivot means between said hanger and motor having an axis parallel with the plane of movement of said hanger whereby the motor may swing in a plane at right angles to the plane of movement of said hanger, an arm attached to said motor, a second arm pivoted to said first arm for movement about an axis substantially parallel with the axis of said motor shaft, a rotatable tool holder mounted for rotation on said second arm about an axis substantially parallel to the axis of said motor shaft, and transmission means carried by said arms for driving said tool holder from said motor shaft.

9. In combination a base, an upright carried by the base, an electric motor having a shaft, a hanger pivoted to said upright about a substantially horizontal axis and adapted to swing in a substantially vertical plane, pivot means between said hanger and motor having an axis parallel with the plane of movement of said hanger whereby the motor may swing in a plane at right angles to the plane of movement of said hanger, a pair of jointed arms, one of said arms being attached to said motor and being adapted to swing with said motor in a plane at right angles to the shaft of said motor, a rotatable tool carried by the other arm, and means for driving said tool from said motor shaft.

10. In combination a base, an upright carried by the base, an electric motor having a shaft, pivot means between the motor and upright for guiding the motor for movement about two axes at right angles to one another, an arm attached to said motor, a second arm, pivot means between the two arms for guiding the arms for relative movement about two axes substantially at right angles to one another, a rotatable tool carried by the second arm, and transmission means carried by the arms for driving the tool from the motor shaft.

HAROLD J. POND. CARL O. LARSON.

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