US 2713757 A
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July 26, 1955 E. BRENNECKE FLOORFINISHING MACHINE 2 Sheets-Sheet 1 Filed Feb. 11, 1953 INVEN TOR: Erns' .BrennecK July 26, 1955 Filed Feb. 11, 1955 E. BRENNECKE FLOOR-FINISHING MACHINE 2 Sheets-Sheet 2 INVENTOR:
ERNST ERE/VNECKE BY: ww@
Unite This invention relates to tloor-nishing machines.
Floor-finishing machines are known which serve for cleaning or smoothing wooden floors and operate on the iioor by means of steel cuttings or with abrasive paper for the purpose of cleaning the surface of the iioor, smoothing out any irregularities or even removing a thin layer ofthe Hoor in order to impart to the latter a smooth i surface lying in one plane. Where the machines referred to operate with steel cuttings, the weight of the machine must be comparatively heavy in order to be able to provide the considerable pressure on the iioor which is required for this type of operating means. Moreover, the speed at which the steel cuttings are moved in relation to the oor must not be too great, because otherwise the result is unsatisfactory.
The present invention is based on the recognition that a satisfactory abrading action can be produced by using abrasive paper instead of the steel cuttings, even with moderate pressure and comparatively rapid movement of the abrasive paper in relation to the floor, so that it is possible, with suitable adjustment, to use as abrading machines the normal commercially available and comparatively light floor polishers which operate at a high sneed.
l it is obvious that there is nothing to prevent the use of ocr-inishing machines which are constructed from the outset as abrading machines and which in accordance with the foregoing remarks comprise a brush plate which is mounted to rotate about a vertical axis and is driven oy an electric motor at a correspondingly high speed, it in accordance with the invention, the brush plate comprises an annular brush suitable for supporting the ma chine and a removable iiexible abrading sheet inside the said annular brush, which sheet is iitted on a support of elastically yieldabie material which is supported opposite the brush plate, means being provided between the brush plate and the said support in order to press the abrading sheet with a predetermined pressure, independent of the total weight, on to the floor, the remaining part of the weight being carried by the annular brush. It is preferable to arrange said supoprt so that in the vertical direction it is supported resiliently and for movement in space relatively to the brush plate, for example, by using a series of helical springs which are arranged around the plate and which are preferably adjustable and interchangeable. By means of such a oordinishing machine, a floor, even when it is waxed, is capable of being abraded in a rapid and satisiactory manner without the floor itself being substantially worn down. Accordingly, with such machines, a well-tended floor can have the surface dirt uniformly removed in just the same manner as was hitherto only possible with relatively great expenditure of time and energy when using steel cuttings or steel wool, with the further advantage that the abrading action of the abrasive sheet is found from experience to last Va long time, since the danger of clogging the pores of the said sheet is smaller than is the case as regards the rendering inoperative of the steel cuttings by clogging of the intertates arent lil stices and caking together of the bundle of steel cuttings.
An embodiment of the invention is shown by way of example in the accompanying drawing, in which:
Fig. l is a cross-sectional view of the abrasive disk, its supporting plate and drive plate.
Fig. 2 is a segmental plan View of the central portion of the abrasive sheet and Fig. 3 is a cross-sectional View of a conventional oor surfacing machine.
The floor-finishing machine, not all of which is shown, comprises in the manner customary with mechanical polishers, a brush plate 1 which is rotatable about a vertical central axis A-A and is mounted on a frame (not shown), said brush plate being adapted to be driven in a manner known per se by an electric motor having a comparatively high speed. The brush plate 1 has at its edge an annular brush which is made so strong that it is suitable for supporting the machine. Arranged inside the annular brush 2, is a flexible abrasive sheet 3 which is suitable for working on the iioor to be treated and which is seated on an annular support 4 of elastically yieldable material, for exam-ple sponge rubber, supported opposite the brush plate. The abrasive sheet 3 can be secured to the support 4 in a detachable manner, for example by adhesives, so that it is possible to replace said sheet by another after it has Vbecome worn.
The support 4 is mounted on the side adjacent the abrasive sheet 3 on a disc 5 of rigid material, for example wood or metal, the two parts being rigidly connected with one another, for example, by gluing, cementing or vulcanising. rl`he abrading sheet is pressed upwardly domefashion at its centre for about half its diameter and bears on the disc k5 with interposition of a rubber pad or the like 6 and an intermediate element 7. The central portion may also serve as a direct and only securing means for the abrading sheet relatively to the disc 5, by the fact that it is, for example, rictionally connected with the disc by pressing it on with a screwing motion, in which case the pad 6 may perhaps be dispensed with. The said domelike central portion does not carry any abrasive coating, since it does not come into contact with the floor. The cavity formed by the dome-shape relatively to the floor is suitable lor accommodating the said iixing means which may be used for securing the abrading sheet relatively to the disc 5 without any danger of said means coming into contact with the lloor.
As shown in Fig. 2, the central portion of the abrading sheet 3 is preferably formed with a series of radial slots 1l "forming triangular segments l2 so that it can be adapted to local irregularities in the iloor by suitable elastic yielding of the support 4. The larger the dome-shaped central portion, the more the slots il are spread open.
The brush plate and the Vdisc S are formed with a series of coaxial bores which are arranged equidistant from the axis of rotation A-A and a driver pin d formed as a' screw .bolt `is passed through each of these bores. The head .of each screw bolt is arranged in a corresponding countersinking of the brush plate Si, the screw nut 9 being disposed in a corresponding recess of the support 4. Arranged between the brush plate lan-d the disc 5 is also a series of helical springs itl which are constructed vas compression springs, each helical spring being disposed Acoaxially of a pin 8. By means of the helical springs l0, the support d together with the disc 5 is resiliently supported vertically in relation to the brush plate l and is at the same time capable orn movement in space. The initial tension of the helical springs lil be adapted to actual requirements by tightening or loosening the screw nuts '9. Moreover, the spring characteri ic can also be adapted to actual requirements by repla the helical springs by other weaker or stronger springs. As will be seen from the drawing, the initial tension and dimensions of the helical springs are such that in the normal position, the disc 5 and thus the support 4 bear indirectly on the stop formed by the screw nuts, whereby the abrading sheet projects a few millimetres relatively to the annular brush 2.
'Ihe other machine parts shown in Fig. l are of conventional construction. The brush plate 1 is iixedly attached to a drive wheel 28 which is supported for rotation about a vertical axis by a ball bearing 13, which in turn is mounted in the housing 25. The drive wheel 2S is provided on its upper face with an annular friction member 14 which can engage with the friction wheel 15, xedly attached to the shaft of the drive motor 16. The frame 26 of the drive motor is under the inuence of a compression spring 17 which tends to tilt the motor, pivotally carried by pins 18, in the direction of the arrow 19, to press the friction wheel against the friction member 14. In the position of rest, shown in the drawings, engagement between elements 14 and 15 is prevented by an extension 20 fixedly attached to the rear of the motor housing, which extension is provided with a notch 21, engaging with an arresting pin 22, fastened to the handle 23 of the machine. The handle 23 is tiltable about a pin 24 in the direction of the arrow 27, whereby, when the handle is tilted in the direction of this arrow, the arresting pin 22 leaves the notch 21 so that the motor is free to tilt under the infiuence of the spring 17 in the direction of the arrow 19 whereby the drive wheel 15 will engage with the friction member 14. In this position, the motor will drive the wheel 28 and therefore also the brush plate 1 connected to the wheel 22.
When being used, the machine is placed on the oor with the brush plate assembly in the position illustrated and, due to the aforementioned projecting position of the abrading sheet 3 relatively to the annular brush 2 which is shown in the drawing, said sheet 3 is the first to bear on the floor. However, under the total weight of the machine, the suitably dimensioned helical springs 10 yield until the annular brush 2 is ilush with the floor. Since this annular brush is suitable for supporting the machine, it takes up the remaining portion of the weight, which obviously may also be the main part of the total weight, so that now the abrading sheet 3 or rather the annular zone thereof which is provided with the abrasive coating and which is disposed underneath the support 4, is pressed ou to the floor with a predetermined pressure which is dependent on the characteristic of the helical springs 10 and the initial tension thereof. This pressure is therefore independent of the total weight of the machine and can in each case be determined in advance according to requirement, by the choice of springs. If the brush plate 1 is now caused to revolve at high speed about the vertical axis A-A by means Vof the electric motor which is not shown, the driver pins 8 which are mounted fast in the brush plate 1 by means of the heads of the threaded bolts carry the disc 5 with them, since the latter is not rotatable relatively to the brush plate 1 on account of the pins, although it is displaceably guided in the direction of the axis A-A and can also assume an inclined position in any direction relatively to this axis A-A owing to the three-dimensional arrangement provided by the helical springs 10. if the machine is now pushed in accordance with working conditions over the oor, then first of all the abrading sheet 3 with its annular Zone provided with an abrasive coating is automatically adapted to local irregularities in the floor surface owing to the fact that the elastica-ily yieldable support 4 yields accordingly at each of such local irregularities, so that it might be said that the flexible abrading sheet 3 participates in these movements without resistance. On account of the radial slots which are provided at the central raised portion, such a yielding is assisted without creases or other deformations being able to occur in the raised portion of the abrading sheet. Relatively large irregularities in the oor, especially of those of relatively large area, are overcome by suitable individual compression of separate helical springs 1t), the disc 5 together with the support 4 and the abrading sheet 3 being adjusted to a suitable inclined position relatively to the axis A-A. This is the case for example when the machine is pushed over a floor strip or the edge of a sill. In this manner, it is possible for the position and also the shape of the abrading sheet to be adapted to all possible eventualities in the sense of a best possible constant contact of the abrading surface with all parts of the floor which is to be treated.
As already mentioned at the outset, an existing polisher can also be converted into an abrading machine of the aforementioned type simply by providing the brush plate of this polisher along the edge with a narrow annular brush corresponding to that indicated by 2 in the drawing and the necessary additional means characteristic of the present invention being arranged inside the annular brush.
What I claim is:
l. In a floor-finishing machine having a brush plate mounted to rotate about a vertical axis and driven by an electric motor, an annular brush suitable for supporting the machine and carried by said brush plate, a detachable flexible abrading sheet inside said annular brush, said abrading sheet being carried on a support of elastically yieldable material, and means arranged between the support and said brush plate in order to press said abrading sheet on to the oor with a predetermined pressure which is independent of the total weight, the remainder of the weight being suppored by said annular brush.
2. In a floor-finishing machine according to claim l, said support being supported in the vertical direction resiliently with respect to said brush plate.
3. In a floor-finishing machine according to claim l, said support being supported for movement in space relatively to said brush plate.
4. In a Hoor-finishing machine according to claim 1, said support being guided so as to be non-rotatable but vertically displaceable relatively to said brush plate by driver members.
5. In a Hoor-finishing machine according to claim l, said support consisting of sponge rubber.
6. In a floor-finishing machine according to claim 1, said support being of annular shape and said abrading sheet being pressed upwardly dome fashion into the cavity of said support.
7. In a floor-nishing machine, a brush plate mounted to rotate about a vertical axis, an electric motor adapted to drive said brush plate, an annular brush adapted to support said machine and carried on said brush plate, a detachable exible abrading sheet inside said annular brush, said abrading sheet being carried on a support of elastically yieldable material which is carried on the other side on a disc of rigid material, a series of heical compression springs arranged around said disc and said brush plate, a driver pin guided through each of said helical springs, said pins connecting said disc and said brush plate so that they are non-rotatable but vertically displaceable relatively to one another and forming a stop on which said disc bears indirectly when relieved of weight, so that the abrading sheet projects a few millimetres beyond said annular brush, said helical springs being of such dimensions and having such an initial tension that when the machine is resting with said abrading sheet on a iloor, they press said sheet on to the tloor with a predetermined pressure which is independent of the total weight, the remaining part of the weight being supported by said annular brush.
8. In a floor-finishing machine according to claim 7, said abrading sheet being pressed upwardly dome fashion in its central portion and having radial slots so that it can be adapated to local irregularities in the floor by suitable elastic yielding of said support.
(References on folla-wing page) 5 References Cited in the le of this patent UNITED STATES PATENTS 373 613 1,345,374 Hodny July 6, 1920 620,782 2,152,352 Holt Mar. 28, 1939 5 730,509 2,379,141 Fuller June 26, 1945 6 FOREIGN PATENTS Great Britain May 23, 1932 Germany Sept. 15, 1932 France Aug. 17, 1932