US2715804A

US2715804A - Sanding machine

Info

Publication number: US2715804A
Application number: US394242A
Authority: US
Inventors: David R Wickes
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-11-25
Filing date: 1953-11-25
Publication date: 1955-08-23
Anticipated expiration: 1972-08-23

Description

Aug. 23, 1955 D. R. WICKES SANDING MACHINE Filed Nov. 25, 1953 o Ja 46 56 3o @e .5 MM e. w o 3 y ,m W Q, 4 o 3 6 6 e J 3 M \4 y H Q h 6 T4 L* W, 4 ,w x WM fr a a .fm gm a a iV 6! ab 4 s Xl -J m United States Patent() SANDING MACHINE David R. Wickes, Detroit, Mich. Application November 25, 19573, Serial No. 394,242

7 Claims. (Cl. 51-170) This invention relates to a sanding machine and more particularly to a sanding machine that is arranged to be manipulated manually.

It is an object of this invention to provide a sanding machine which is compact, which is of a size and shape to be conveniently grasped and manipulated with one f hand and which, at the same time, is of simple construction and incorporates a minimum of parts.

In the drawings:

Fig. l is a side elevational view of the sanding machine of this invention.

Fig. 2 is a side elevation of the machine with the shield broken away.

Fig. 3 is a fragmentary sectional view along the line 3-3 of Fig. 2.

Fig. 4 is a fragmentary sectional view along the line 4 4 in Fig. 3.

Referring more particularly to the drawings, there is illustrated in Figs. l and 2 a sanding machine which includes a frame on which a motor 12 is supported. In the embodiment illustrated, motor 12 is of the pneumatic type, but it will be appreciated as the description proceeds that the motor for driving the sander can be most any type of small motor for producting rotary motion, for example, an electrical motor. Motor 12 has an air inlet conduct 9 connected therewith. The ow of air to the motor is controlled by a valve, not shown, which is actuated by a pin 11. An operating handle 13 is pivotally supported on frame 10 and is arranged to be depressed when the sander is grasped in the palm of the hand to actuate pin 11 and thereby admit air to motor 12. A shield 1S is mounted on frame 10 as by screws 17 and encloses the moving parts of the sanding machine and thereby protects the operator from injury. The motor 12 is mounted on frame 10 by means of screws and nuts such as illustrated at 14. Motor 12 has a depending shaft 16 which projects below frame 10 and is journalled at the lower side of the frame in a bearing 18.

Below frame 19, there is arranged a sanding plate 20 on which a padded plate 22 is slidably arranged. Plate 22 has upturned ends against which the spring clamps 24 are arranged to engage to hold a piece of sand paper on the bottom side of pad 26 which is cemented or otherwise attached to plate 22. A pair of

bearing blocks

28 and 30 are ixedly mounted on sanding plate 2G as by screws 32. Plate 20 is pivotally supported below frame 10 by four links 34 arranged in pairs at each end of the frame. It will be observed that the

bearing blocks

28 and 30 are relatively narrow as compared with the width of sanding plate 20, and links 34 are therefore relatively closely spaced and in symmetrical relation with respect to the axial center line of plate 20. The pivotal connections between the links and the respective members to which they are connected are the same at both the lower and the upper ends of the links. These connections at the lower ends of the links are illustrated in Fig. 3.

Blocks

28 and 30 are provided with transversely extending bores 36 in which are press litted rubber bushings 38. The

2,715,804 Patented Aug. 23, 1955 ICC bushings 38 are preferably formed of pure gum rubber having a high tensile strength and a Durometer hardness of about 60 to 65. These bushings can, however, be formed of neoprene having a Durometer hardness of about to 55. Within each of the rubber bushings 38 there is press fitted a steel sleeve 40 which extends outwardly beyond each end of the bushings 38. Screw 42 and nut 44 are employed for clamping the end portions of links 34 against the ends of sleeves 40. Nuts 44 are tightened sufficiently so that links 34 are fixed and cannot rotate relative to sleeve 40. The pivotal connections between the upper ends of lines 34 and frame 10 are the same as illustrated in Fig. 3 and therefore need not be described. It will sutice to say that with this arrangement, pivotal movement of the links with respect to the frame 10 and bearing

blocks

28 and 30, with which the links are connected at opposite ends, produces a circumferential distortion of rubber bushings 38. Furthermore, it will be observed that as the links 34 oscillate about their pivotal connections at their upper ends with frame 10, plate 20 is caused to oscillate back and forth along a straight line with respect to the longitudinal central axis of frame 10.

In order to drive plate 20 from motor 12, there is provided a connecting rod 46 which is pivotally connected at one end to bearing block 30 and which is pivotally connected at its other end to motor shaft 16. The connection between connecting rod 46 and motor shaft 16 is generally illustrated in Fig. 2. This connection is eccentric and includes a bearing 5G seated in connecting rod 46 through which a screw 52 extends upwardly and is engaged in an oft center threaded opening 54 in the lower end of motor shaft 16. Screw 52 also secures to the lower end of shaft 16 a pair of counterbalance weights 5S arranged one above and one below connecting rod 46. When shaft 16 is rotated, the end of connecting rod 46 that is connected to motor shaft 16 is caused to travel in an orbital path.

The pivotal connection between the other end of connecting rod 46 and bearing block 38 is best shown in Fig. 4. Bearing block 30 is provided with straps 56 on the upper and lower faces thereof which extend inwardly toward the center of the sanding machine and which provide a bifurcation 58. Adjacent the free ends of straps 56, holes are provided for the reception of screw 60.

Screw extends upwardly through plate 20 and is provided with a nut 62 at its upper end for bringing straps 56 into a clamping engagement with the ends of a hardened steel sleeve 64. Sleeve 64 has a close tit with a bronze bearing 66. Bearing 66 is press tted into a rubber bushing 68 which is in turn press fitted in a bore 70 extending vertically through the end of connecting rod 46.

It will be observed that the use of bushings 38 at the pivotal connections between links 34 and the frame 10 at the upper ends of the links and the

bearing blocks

28 and 30 at the lower end of the links provides an economical pivotal connection between these members. The use of such rubber bushings eliminates the need for expensive bearings or the like and also eliminates the problem of wear. The use of the rubber bushing 68 at the pivotal connection between the end of connecting rod 46 and bearing block 39 is also advantageous for several reasons. In the first place, it will be noted that as the links 34 oscillate back and forth, there may be a slight tendency for sanding plate 20 to rock relative to frame 1i). Since the connection between the one end of connecting rod 46 and the lower end of motor shaft 16 is more or less rigid, this tendency to rock will be absorbed by the alternate compression and expansion of bushing 68. Bushing 68 also compensates for any misalignment at this connection.

Counterbalance weights S5 are provided for oifsetting conventional bearings.

Venables the screw 60 to tilt slightly with respect to con- 3 the side thrust imposed upon the sanding plate by connecting rod 46. Normally the connecting rod 46 would have a tendency to oscillate the sanding plate 20 in an elliptical path rather than with a straight line reciprocating movement. This would have a tendency torc'ause the four screws 42 extending through therupper and lower Yment.l However, even if this twisting movement is not entirely eliminated by the balance weights 55, this twist- Ving is absorbed, by the bushings 38.

Thus, it will be seen that l have provided a sanding Vmachine which is of Vrelatively simple construction but,

nevertheless, is designed to produce a substantially straight line reciprocating movementv of the sanding plate. The

ment between the members connected thereby and, at the same time, are not subject to wear as is the case with Rubber bushingA 68, Yin'addition,

necting rodV 46 and thus relieves any strain that might otherwise be imposed upon the pivotal connection between the lower end of motor shaft 16 and connecting rod 46 by reason of the oscillation of links 34. The use of the hardened steel sleeve 64 having a close fit with the bronze bushing 66 is desirable for several reasons. 'In Ythe first place, it enables the connecting rod to pivot freely aboutY screw 60. In addition, sleeve 64 is slidably arranged in bearing 66 and is Ytherefore free to move up and down in bearing 66 as the sanding plate 20 raises and lowers in response to the pivotal movement of links 34. i VI claimi 1. In a sanding machine, the combination of a motor a frame on Vwhich'saidrmotor is mounted with the motor shaft extending downwardly through said frame, a plate below said frame on whicha strip of sand paper is arranged to be attached, a pair of bearing blocks rigidly mountedon and one adjacent each end of said sanding plate', a pair of generally uprightflinks at each end of saidV frame, said links having a pivotal connection attheir upper ends with said frame and being journalled attheir lower ends for pivotal movement on said bearing blocks,

a support xedly mounted on said plate between said bear-y ing blocks, a connecting rod having a pivotal connection with said fixed support at one end and having an eccentric pivotal connection at its other end with the lower end of saidmotor shaft, said pivotal connection Vbetween said connecting rod and said iixedV support including a Vcompressible and resilient bushing which permits the connecting rod to oscillate angularly with respect to said sanding plate, and a counterbalance weight operatively connected'with said motor shaft.

2. The combination set forth in claim l wherein said pivotal connections between said links and said'frame i Y. and bearing blocks each include a rubber bushing ixed a frame on'which Vsaid motoris mounted with the motor shaft extending downwardly through said frame, a plate Vrubber bushings provided compensate for any misalignbelow said frame on which a strip of sand paper is arranged to be attached, a pair of bearing blocks rigidlyV mounted on and one adjacent each end of said sanding plate, a pair vof generally upright links at each end of said frame, said links having a pivotal connection at their upper ends with said frame and being journalled at their lower ends for pivotal movement onrsaid bearing blocks, said pivotal connections ,each including a rubber bushing which is fixed with respect to the link and to the frame or bearing blocks to which the end of the link's are connected, a support flxedly mounted on said sanding plate, a connecting rod, said connecting rod having a Vvertical boretherethrough adjacent one end, a rubber bushing tixedly mounted in said bore and having ay sleeve iixedly supported therein, a pin arranged for rotation and vertical sliding movement in said sleeve and rigidly connected with said support for providing a pivotal connection between said plate and said connecting rod, means forming an eccentric driving connection between the other end of said connecting rod and the lower end of-saidV motor shaft, and counterbalance weight means secured to symmetrically with respect to the Vaxial center line of said sanding plate. l 6. The combination Vset forth in claim 4 wherein said pairs of linksrare parallel and the links in each pair areV closely spaced relative to the width of said sanding plate.

7. In a sanding machine, the' combinationof a motor, a frame on which saidrmotor is mounted` with the motor shaft extending downwardly through said frame, a plate below said frame on which a strip of sand paper is arranged to be attached, a pair of bearing blocks rigidly mounted on and one adjacent each end of said sanding plate, a'pair of generally upright links at Veach end of said frame, said links having a pivotal connection at their upper ends with said frame and being journalled at their lower endsrfor pivotal movement on said bearing blocks, a support tixedly mountedY on said plate, a connecting rod extending in a plane generally parallel to the plane of said plate, saidrconnecting rod having a vertical bore,Y

therethrough adjacent one end, a rubber bushing xedly mounted in said bore and having a sleeve fixedly supported therein, a pin fivedly mounted on said support,` said pin extending through said sleeve, said sleeve being of said motor shaftand counterbalance weight meansk secured to the lower end of said motor shaft and designed to offset the natural gyrating action of the plate and the'y inertia of the plate resulting from Ysaid eccentric'connection.

Y References Cited in the le of this patent UNITED STATES PATENTS Champayne e Jan. 23, 1945 Dobson Aug. 8, 1950