Dry grinding terrazzo floor finishing machine

[57] ABSTRACT

The invention relates to a machine for the dry grinding of terrazzo floors and particularly to the utilization of a vacuum cleaner attachment for the collection and control of dust raised during the grinding operation. This dust comprises fine particles ground from the floor, sand used for dressing the grinding stones and small particles worn from the grinding stones. A chamber of the machine in which the grinding stones are disposed has a vacuum pick-up head and the chamber is formed in part by a loose fitting skirt assembly which is resiliently biased in a downwardly direction. A wear shroud forming the lower part of the skirt assembly is biased into firm engagement with the floor and adjustable vent plates are provided for controlling the flow of air through the chamber. The dust collecting assembly for the machine comprises a drum unit mounted on a wheeled cart which is closely coupled to the machine so that the drum unit is within the lateral confines of the handle of the machine.

Claims, 5 Drawing Figures

<img file="US3701221A_D0001.tif" />

PATENTED OCT 31197Z

SHEET 1 OF 3

3.701.221 oor

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INVENTOR.

Franli H \)in Gila

BY

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attozajev

PATENTEDoct ai m

3.701.221

SHEET 2 OF 3

<img file="US3701221A_D0004.tif" />

INVENTOR.

BY

Fran^ P. ‘Όίη&amp;Πα

<img file="US3701221A_D0005.tif" />

JT7O£/UEV

PATENTED oct 31 b?z

3,701.221

SHEET 3 OF 3

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<img file="US3701221A_D0007.tif" />

3,701,221

DRY GRINDING TERRAZZO FLOOR FINISHING MACHINE

This invention relates to a machine for the dry grinding of terrazzo floors and particularly to an improvement relating to the utilization of a vacuum cleaner attachment for the collection and control of dust raised during the grinding operation. This dust comprises finely ground particles from the floor, sand used for dressing the grinding stones and small particles worn from the grinding stones.

A main object of the invention is to provide a new and improved terrazzo grinding machine for the dry grinding of terrazzo floors and particularly a new and improved dust control and collecting system for such machines.

Other objects and advantages of the invention will become apparent from the following specification, the drawings and appended claims.

In the drawings:

FIG. 1 is a perspective view of a new and improved terrazzo floor dry grinding machine embodying the invention;

FIG. 2 is a perspective view similar to FIG. 1 but shows the vacuum cleaner drum unit removed and the grinding head assembly of the machine in a tilted position which position is normally used to facilitate the replacing of grinding stones;

FIG. 3 is a front elevational view of the skirt assembly which forms the grinding stone chamber portion of the grinding head assembly;

FIG. 4 is a fragmentary perspective view showing fastening means for the attachment of the skirt assembly; and

FIG. 5 is a fragmentary perspective view of a rear portion of the grinding head assembly showing a fitting for a vacuum cleaner hose, the drum unit cart and the hitch for the cart.

Referring to the drawings, and particularly FIGS. 1 and 2, the terrazzo floor grinding machine consists of three main parts which are a motorized grinding head assembly 5, a two wheeled carriage assembly 6 for making mobile or mobilizing the grinding assembly 5, and a dust collection assembly 7 which includes a vacuum unit 8 and a three wheel cart 9.

The grinding head assembly 5 includes a main frame or casing part 10 which is a generally rectangularly shaped member having vertically extending walls, with rounded corners, forming the sides thereof. A horizontally extending plate member 12 is attached to the top of casing part 10 with a plurality of bolts. A 220 volt electric motor 15 is centrally mounted on the plate 12 with the shaft thereof (not shown) extending vertically and downwardly into the confines of casing part 10 beneath plate 12.

An electrical box 16 is mounted on plate 12, in front of the motor 15, which contains electrical control apparatus for the motor. Another electrical box 18 is mounted on plate 12, behind the motor 15, which is a service box for receiving electrical power from a supply outlet through a cable 20 having a male connector 21. Power for the motor 15 is supplied through the service box 18. A cable 23 extending from service box 18 serves to supply power to the motor of the vacuum unit 7.

A downwardly extending sheet metal skirt or shroud 30 is fixedly attached with lugs and screws 31 (see FIG.

2) to the casing part 10. The shroud 30 has outer dimensions which are nominally the same as the inner dimensions of the casing part 10 so that the shroud is nested inside member 10. Within the lateral confines or space defined by shroud 30 are four spiders 32 each of which has a centrally disposed shaft 34 by which the spiders are symmetrically located and mounted for rotation about vertical axes. Each spider 32 has three radially extending arms or spokes with a grinding stone 36 being attached to each spider arm.

Within the lateral confines or space defined by casing part 10 is a gear assembly (not shown) which is driven by the motor 15 and functions to rotate the spiders 32 about the axes of their shafts 34. The rotation of the spiders 32 cause the stones 36 to move in orbital paths relative to the axes of the spider shafts 34, in a known manner, to effect the grinding of terrazzo floors. When the machine is in operation the stones 36 support the weight of the grinding head assembly 5 which includes the frame 10, the motor 15 and the enclosed gear assembly. By way of example, a typical or representative terrazzo grinding machine might have each spider 32 support a weight of about 125 pounds and have a motor speed such that the linear speed of each stone 36 is about 1500 feet per minute.

With reference to FIGS. 1 to 3 there is illustrated a skirt assembly 39 which depends downwardly from the shroud 30 in surrounding relation to the spider units 32. Skirt assembly 39 includes a rectangularly shaped sheet metal support member 40 which is formed with four vertically extending wall portions having rounded comers which correspond to the rounded corners of shroud 30. A wear shroud 42 made from a sheet stock of wear resistant nylon material surrounds support member 40 and is attached thereto with a plurality of screws 44. Shroud 42 is similar in shape to support member 40 but has a somewhat lesser height. The holes in shroud 42 for the screws 44 are vertically centered whereas tapped holes for screws 44 in support member 40 are located along the lower edge of support member 40. Shroud 42 is illustrated as being formed with four parts with two of the parts having the reference numerals 42α and 42Z&gt; and the other two parts forming front and rear inlet or vent plates 46 and 47 which are not only separately attached to the support member 40 but are also adjustable attached thereto such that they can be raised to desired adjusted positions. The adjustment feature is facilitated by three spaced apart vertically extending slots 48 in each of the vent plates 46 and 47 and screws 49 which are also threadedly received in tapped holes in support member 40.

The skirt assembly 39 is attached to frame member 10 with elongated brackets 50 and 51 which are vertically extending and have the lower ends thereof attached with screws 53 to support member 40. The upper ends of brackets 50 and 51 have slots 54 which facilitate the attachment of the skirt assembly 39 to the frame member 10, this being referred to further on herein.

Support member 40 has a row of tapped holes for receiving screws 60 which holes are spaced above the row of tapped holes which receive the screws 44. Screws 60 are utilized for attaching a rubber or plastic sealing strip 62 and an articulated four piece metal strap 64 to support member 40. The lower part of seal3,701,221 ing strip 62 conforms or is fitted to the peripheral shape of support member 40 while the upper part of the sealing strip 62 extends above and upwardly relative to the upper edge of support member 40.

Skirt assembly 39 is resiliently biased towards the 5 floor with the utilization of resilient connections provided between brackets 50 and 51 and the frame plate member 12. The resilient connection associated with bracket 51, shown in FIG. 4, is identical to the resilient connection for bracket 50. The connection includes an ‘θ L-shaped bracket 66 having apertured horizontally and vertically extending legs. The vertically extending leg is adjustable attached to the skirt bracket 51 with a screw and nut fastener 68. An adjustment screw 70, which threadedly engages a tapped hole in plate 12, passes ¹⁵through a hole in the horizontally extending leg of bracket 66. A helical spring 71 is disposed between the head of screw 70 and the horizontally extending leg of bracket 66. With the above described construction the 20 brackets 50 and 51, and hence the entire skirt assembly 39, are resiliently biased in a downwardly direction such that the wear shroud 42 is biased into firm engagement with the floor.

Wear shroud 42 is of course subjected to wear during 25 use. When new, and prior to being subjected to wear, the shroud 42 is vertically symmetrical relative to the screws 44. After the lower edge thereof becomes worn the two shroud parts 42α and 42i&gt; can be taken off, turned “upside down” and reattached so that the other 30 or upper edge thereof may also be subjected to wear. The same is true for vent plates 46 and 47.

In FIG. 5 there is shown a fitting 74 which is attached to and extends from the frame member 10. A passage (not shown) extends from the fitting 74 to an air inlet head 76 (FIG. 2) mounted interiorly of the chamber defined and surrounded by the shroud 30 and the skirt assembly 39.

In the grinding of terrazzo floors the grinding operation involves the undesired production of dust which is made up of particles from the terrazzo floor and silica particles worn from the grinding stones 36. The chamber formed by the shroud 30 and the skirt assembly 39 has fluid tight sealing at the top thereof by reason of the upper lip 78 of the sealing strip 62 extending inwardly into sealing engagement with the shroud and fluid tight sealing at the bottom thereof (except for the vent plates 46 and 47) by reason of the wear shroud 42 (parts 42α and 42b) being resiliently biased 50 downwardly into engagement with the floor.

The grinding head assembly 5, which includes casing part 10 and motor 15, is made mobile for use in grinding floors with the two wheeled carriage 6 which comprises a chassis frame which supports an axle 80 to which wheels 82 are rotatably mounted. Carriage 6 includes two spaced apart, forwardly extending arms 84, the forward ends of which have pivotal connections with the casing part 10. These pivotal connection points having a common horizontal axis which is through the center of gravity of the grinding head assembly 5. A rectangularly shaped handle 86 is fixedly attached to the chassis frame of carriage 6 for facilitating and controlling the movement of the grinding head assembly 5 in the floor grinding operations.

The wheeled cart 9 comprises a generally circularly shaped frame member 92 having three wheels 94 in spaced relation to each other. A detachable hitch 96 is provided between the cart 9 and carriage 6 so that the cart 9 functions as a trailer relative to the carriage 6. Frame 92 has cross pieces 98 for supporting the cylindrically shaped vacuum drum unit 8. Vacuum drum unit 8 has incorporated therein an electric motor 100 and suction fan unit (not shown) and a conventional suction hose 102 extends from the upper part of unit 8 to the fitting 74 on casing part 10 to which it is detachable connectable. An electric cord 104 extends from the motor 100 and is shown connected to the electric cord 23 which extends from the service box 18. Fitting 74 provides fluid communication between the hose 102 and the interior space defined by the shroud 30 and the skirt assembly 39. The vacuum pick-up unit or head 76 disposed in this interior space has fluid communication with the vacuum unit 8 through the fitting 74 and the hose 102.

Carriage assembly 6 has a bracket 110 immediately above the wheel portion 72 thereof for holding a counterbalancing weight 112. During the floor grinding operations the entire weight of the grinding head assembly 5 is supported on or by the grinding stones 36. When it is desired to replace worn stones the dust collection assembly 7 may be detached or removed by the disconnecting of cart 9 from the carriage 6, disconnecting hose 102 from the fitting 74, disconnecting the electrical cord 104 from the electrical cord 23, lifting the drum unit 8 from between the confines of handle 86, and pivoting the machine about the axis of the wheels 82 as shown in FIG. 2. The weight 112 is moved to the upper part of the handle 86 to hold the machine in the pivoted position of FIG. 2 and, with the machine in this position, the grinding stones 36 may be replaced.

On the other hand, the machine may be designed so that the head assembly 5 may be tilted back as illustrated in FIG. 2 without disconnecting the cart 9 from the carriage 6. In that case it would also not be necessary to make the other disconnections referred to above such as the hose 102 from the fitting 74, the cord 104 from the cord 23, or lifting the drum from the confines of handle 86. It might be desirable to remove the hose 102 as a matter of prudence, however, so as to avoid accidental stressing or damage.