US 3094819 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
June 25, 1963 E. MUAQSCHEI. 3,094,819
SANDING MACHINE Filed'Aug. 6, 1962 5 Sheets-Sheet 1 22 22 Jnvenar':
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June 25, 1963 E. MuRscHEL 3,094,819
sANnING MACHINE Filed Aug. e, 1962 s sheets-sheet a 1`4 54 64 4s 5o ya 52 5 92 afz as 102100 69 9o 10a 88105 4 o zo s" WW2/21mm@ /I-H-orneys United States Patent O 3,094,819 SANDING MACHINE Erwin Murschel, Stuttgart-Weilimdorf, Germany, assignor to C. F. Scheer & Cie., Stuttgart-Feuerbach, Germany Filed Aug. 6, 1962, Ser. No. 215,156 Claims priority, application Germany Aug. 10, 1961 17 Claims. (Cl. 51-170) This invention relates in general to sanding machine construction and in particular to a new and useful hand belt sander having improved means for adjusting the tensioning and the run of the belt automatically.
The present invention is an improvement over previous -belt sanding machine constructions, particularly in respect to the means for mounting the tensioning roller to permit easy adjustment thereof at a location within the roller. Such means permit adjustment both in outward and inward tensioning directions and in directions along lthe roller axis. The inventive construction also provides improved means for insuring guidance of the belt from the `driving roller over the tensioning roller.
With prior art machines of this type it is essential that there is a large 4free space between rollers for the adjusting devices. This, for example, applies to machines which are driven by flexible shafts. In a hand belt sander, however, it is desirable that a driving motor be placed between the driving and tensioning rollers and hence there is no space for any adjustment means.
In accordance with the present invention there is provided ian improved belt san-der construction which includes the housing frame :having handle means thereon which supports a central motor and a driving rollerat one end thereof :and a tensioning 'roller adjustably mounted at the other end thereof. The tensioning roller is advantageously supported from the housing on an adjustable pin assembly which includes means for biasing the tensioning roller in a direction outwardly to tension an endless sanding belt directed thereover whenever the pin assembly is arnanged in this manner. The outward tensioning may be easily removed from the tensioning roller Iby means of a control pin which is arranged to shift a rocking lever supporting the bearings of the tensioning roller so that a biasing spring no longer acts thereon to force the roller in an outward direction tensioning the sanding belt.
YThis inventive construction includes a rocking lever construction supporting the shaft of the tensioning roller which permits both the outward and inward movement of the roller for the purpose of tensioning the belt and also permitting the axial adjustment of the shaft for the purposes of displacing the tensioning roller laterally in those instances where it is desinable to -adjust the run of the belt, such as for diagonal sanding, for example.
The inventive device permits easy changing of the belt by depressing a control pin to remove the tension acting on a roller through a torsion spring arranged in the pin assembly. The rocking lever carrying the tension roller shaft may then be swung easily backwardly with the roller bearings and the tension roller to permit easy re moval of the sanding belt. The improved construction includes means `for adjusting the transverse position of Ithe tensioning roller and for biasing the roller bearing shaft in a predetermined direction during the operation thereof. F[he arrangement permits easy running of the tensioning roller and aslight shifting axially thereof in the even-t of an unbalancing of forces or overload.
A `fur-ther feat-ure of the invention includes means `for mounting adjustable guide elements on each side of the tensioning roller which include arm portions which extend upwardly and then circum-ferentially around the lateral periphery of the belt for insuring the true ru-nning of the tensioning roller and preventing the :lateral displaceice men-t of the belt from the roller. In the event of a onesided load acting on the sanding belt, the belt will run up against one of the guide elements and prevent it from being completely displaced out of alignment. In addition, the running-up pressure is transmitted through the guide elements to the tensioning roller axis which is thereafter rocked or displaced laterally causing the belt to move to the highest plane which is formed by the displacement of the tensioning roller. The guide elements are advantageously constructed as a quarter of -the circle guide rod which overlies the circumference of the tensioning roller adjacent each edge;
A feature of the invention is that the lateral displacement of the axis of the tensioning roller is permitted by a novel mounting means which includes a rockable bearing formed as a partial ball or ball dish construction. The ball or ball-shaped bearing is advantageously held within a socket formed in a bore in the rocking lever and means are provided to urge the ball bearin-g which carries the tensioning shaft in a predetermined direction to one side. The construction advantageously includes means 'for shifting the rocking lever in an axial or transverse direction for the purpose of shifting the tensioning roller for those instances in which it is desirable t-o run the belt at an angle. A set screw element is provided to set the rocking lever in lthe adjusted position. The adjustment is advantageously made by shifting a sliding pin element of the pin assembly which carries the rocking lever at the inner end thereof.
Accordingly, it is an object of this invention to provide an improved hand sander construction.
A further object of the invention is to provide a hand sander which includes a housing supporting a central motor and rotatably supporting a driving roller at one end, and including rocker means pivotally supporting the shaft yfor the tensioning roller, the rocker means being adjustable for tensioning purposes and including means for biasing the rocker means to an loutward tensioning position.
A further object of the invention is to provide a hand sander construction including an improved mounting for a tensioning roller which comprises an improved pin assembly supported in the sander housing and carrying a rocking lever at the inner end thereof with means biasing the rocking lever in an outward position to tension a sanding belt trained around the tensioning roller and -inlcluding a control pin arrangement which may be displaced to effect removal of the action of the biasing means on the roller for the purpose of slackening the sanding belt, such as for removal purposes.
A further object of the invention is to provide an im.- proved hand sander construction which includes adjustable means for supporting the shaft of a tensioning roller to permit axial as well as outward or longitudinal displacement thereof for adjustment purposes.
A further object of .the invention is to provide ka hand sander including an improved support for a tensioning roller which includes a rocking lever having a bore therein with a ball socket portion adapted to receive a ball bearing portion of the tensioning roller shaft, means being provided to bias the shaft in a lateral direction against the bali socket portion against the rocking lever, said rocking lever being displaceable laterally to permit lateral shifting of the location of said tensioning roller.
A further object of the invention is to provide the sanding device which includes means supporting a shaft of a tensioning roller for axial displacement and guide ele- 3 off the side of the tensioning roller, the supporting spindle being mounted so that it will be rocked when the guide elements are contacted by .the belt and displaced thereby.
A further object of the invention is to provide a hand sander construction which is simple in design, rugged in construction and economical to manufacture.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of .this specification. For a better understanding of 4the invention, its yoperating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and Vdescriptive matter in which there are illustrated and described preferred embodiments of the invention.
In the drawings:
FIG. l is a perspective right-hand elevation of a sander constructed in laccordance with the invention;
FIG. 2 is a section taken on the line 2 2 of FIG. l on an enlarged scale;
FIG. 3 is a section taken on the line 3-3, of FIG. l on the same scale as FIG. 2 with the exception itis also extending 4through the tensioning roller axis;
FIG. 4 i-s a partial horizontal top plan of the portion of the sander indicated in FIG. 3;
FIG. 5 is a ri-ght-hand end elevation of the tensioning roller on a slightly larger Iscale than FIG. 2;
FIG. 6 is a section taken on the line 6 6 of FIG. 3 indicating the roller in a non-tensioned position;
FIG. 7 is a section similar to FIG. 6 but indicating the roller in a tensioned position;
FIG. 8 is a fragmentary section of another embodiment of rocker lever mounting for the tensioning roller shaft;
FIG. 9 is a longitudinal section of still another embodiment of rocker arm mounting for the tensioning roller shaft;
FIG. 9a is a top View of FIG. 9; and
FIG. 10 is an enlarged fragmentary side elevation of the control pin and abutment stop.
Referring to the drawings in particular, the invention embodied therein includes a hand vbelt sander indicated in position on a wooden board or plate 10. The sander includes a machine casing 14 provided with a handle 12 at one end thereof. An electrical outlet cord 13 is provided for connecting a driving motor 16V to an electrical power source. The motor 16 is centrally mountedwithin the interior of the casing 14 and includes means (not shown) for driving a drive roller 18 mounted at one end thereof. The tensioning roller 20 is rotatably mounted onY the opposite end and an endless sanding belt 22 is directed over each of the rollers 18 and 20. A guide shoe 24 is provided at the lower side of the motor 16 over which the belt 4runs and the shoe insures the proper positioning of the machine on the workpiece to. be worked upon. In order to suck off any Wood dust which is -accumulated during the sanding, there is provided at the machine casing a suction .device Z6 having a dust receiving bag 28.
In accordance 'with the invention there is provided an improved mounting for the tensioning roller 20 to insure lthe automatic tensioning compensation or equalization as well as the automatic ladjustment of the run of the sanding belt. The adjustable mounting means includes, as best indicated in FIGS. 2 and 3, -a carrier pin assembly generally -designated 32 arranged at a securing Wall 30 of casing 14. By means 'of a suitable mounting or bearing (not shown) both the drive motor 16 and the drive roller 18 are secured at the wall 30. The pin assembly 32 includes an elongated hollow pin piece or member 34 which is slidable in a `bore or groove 37 dened in the wall 30. T he pin 34 is prevented from rotating by means of an extension 3S of a set screw member 40 which rides in an axially elongated groove 36 of the pin member 34. The set screw 40 is threaded in a top portion of a projection of the wall 30 and extends into the groove 36. The set screw 40 may be adjusted manually in order to permit the axial sliding of the pin 34, and notches -or detents 42 are advantageously `cut out along the groove in order to provide spaced anchoring recesses at which the pin 34 may be anchored lby the set screw 40. A rocker arm or lever arm member 46 is rotatably mounted adjacent the inner end of the pin 34. The rocker arm member 46 includes an outer lend with a bore 86 defining an internal socket ledge portion at the inner end thereof for the purposes of receiving a ball shaped bearing mounting 84 for a bolt shaft yor spindle 89 for the tensioning roller ZG.
A torsion spring 50 is twirled around the pin 34 and one of its ends is -held in an adjusting ring 52 and its opposite end bears against the lever member 46 by pressing against a securing ring 54 which extends around the pin 34. The spring exerts a biasing force on the rocking lever member 46 to urge it in an outwardly direction away from the drive roller 1S. This maintains the :roller 20 under an outward biasing to tension the sanding belt 22 which is trained to run therearound.
As indicated in FIG. 4, the right-hand end of the spring 50, designated 56, bears against an abutment pin 5S which is inserted into the ring 52 While the left-hand end designated 60 bears against a holding piece 62 of the rocker arm member 46 to urge it outwardly with `a relatively strong spring force. Due to the action of the torsion spring 50 the tensioning roller is rocked outwardly in accordance with the indication shown in FIG. 7 in a counter-clockwise manner. This insures that the belt 22 Will be maintained in tension during the operation of the device.
In -accordance with the invention, in order to exchange the belt 22 of the machine in a rapid and easy manner, there is provided a control pin 64, as indicated in FIG. 3, which extends through the -hollow pin 34. The pin 64 is slidable in the hollow pin 34. The end of the pin 34 is provided with a forked extension 66 which is angled olf and defines a guideway perpendicular to the axis of the pin. The pin 64 extends through the guideway and is biased in position thereon by spring 72. Rotation of the control pin is impossible When it is located between the forked elements 66. The spring 72 is coiled around the control pin 70 and -abuts against an inner widened portion of the bore of the pin 34 on one end and a control knob 70 on the outer end of the pin 64. At the inner end of the rocker arm 46 there is provided an abutment pin 68 with an inclined or slanted surface 69, las indicated in FIG. 10. When the control pin 64 is moved inwardly in the direction of arrow D, the end is snapped over the abutment 68, as indicated in FIG. 6, .so that the tensioning roller may be moved by hand to the untensioned position lin which the abutment 68 prevents the torsion spring from tensioning the roller. After the |belt is positioned in place, the tensioning may be resumed 4by merely displacing the control pin 64 in the direction of the arrow D once 4again to the extent that the pin will be released from the. abutment 68 Iand the rocker will be retens-ioned by the spring 50.
As mentioned previously, the outer end of the rocker member 46 is provided with a bore 86 for the purpose of mounting the roller axis, which is generally designated by the numeral 82. The ball-shaped' recess is formed at the inner end of the bore 86 and provides a ball socket for =a partial ball joint dish member or bearing 88 to permit slight rotational adjustment, of :an axle or supporting spindle 89, which is carried in the ball joint piece 88. By this arrangement the run of the belt is automatically controlled, so that the belt will always be llush with the inside of the two rollers. The arrangement permits the rocking movement of the spindle or bolt shaft 89 which rotatably carries the tensioning roller 20. For this purpose the tensioning roller 20 includes ra central web wall 20a which carries an elongated barrel portion in which is mounted ball be-a-rings 90. Ball bearings 90 are advantageously axially spaced to provide a secure supporting arrangement for the tensioning roller on t-he bolt member 89.
In accordance with a feature of the invention, one end of the tensioning roller is held in its position by an adjusting ring 92 which is tted over the bolt shaft 89 and secured thereto such as by a set screw (not shown). As indicated in FIG. 5, a stirrup member or guide rod 94 extends radially outwardly from the adjusting ring 92 and includes an arcuate or bent portion which extends circumferentially along the side of the tensioning roller and in closely spaced position in respect thereto, `such as indicated in FIG. 2. As indicated in FIG. 3, the outer surface of the guide rod 92 extends by ran amount a beyond the circumference of the tensioning roller. This -position can be yadjusted by means of the set screw 96 which is arranged in the Iadjusting ring 92 (FIG. 5).
An additional'stirrup member or guide rod 98 is arranged in an extension portion 102 of the bolt shaft 89 :at the opposite end and extends radially and then arcuate- 1y around a portion of the circumference of the tensioning roller in the manner of the guide rod 9'4. A set screw 100 secures the rod in `an adjusted position at the selected he-ight above the tensioning roller. Each of the guide rods 94 and 98 provides means for insuring the proper feeding of the sanding belt 22 over the tensioning roller `and any tendency for the belt to slide off either end thereof will cause a rocking movement of the bolt shaft 89 and an adjustment of the tensioning roller, so that the belt will tend Vto be displaced toward a high portion of the roller andan :auto-matic compensation will `be made.
As indicated in FIGS. 3 and 4 the lball joint piece 84 is provided with a through bore in which is inserted an adjusting pin 105 which is guided in a slot like recess 108 Vformed in the outer end of the lever member 46. Lateral projections of the upper end of the lever member 46 are for-med as outwardly extending spindle guide arms 110 :and 62. In the spindle lguide arm 110, as indicated in FIG. 4, there is arranged `a threaded spindle 112 which may be threaded into the guide 110 against the force of a compression spring 114 to cause an outer end thereof to bear -against the adjusting pin 105. The spring 115 heldin the guide spindle 62 bears against the opposite end of the pin 105 so that the ball piece 84 always bears in t-he socket 86 under a predetermined biasing force. This permits adjustment of the bolt shaft 89 by rocking movements against the biasing force to accommodate for any unbalancing forces for -acting on the sanding belt. "Iihe arrangement also permits the guide rod members 94 Iand 98 to rock the bolt shaft 89 when the belt becomes misaligned on the tensioning roller. If it is desired it is also possible to release the Set screw 40 and shift the position of the pin 34 so that the tensioning roller 20 may be positioned on the opposite side of the housing and the belt run at an angle -so that the sanding m-ay be made in an excellent and clean manner on angular surfaces.
' In FIG. 8 another embodiment of a rocker bearing mount is indicated which includes a rocking lever member 122 rotatably mounted on a pin 120. As in the previous embodiment the rocker is held in a tensioned position by a torsion spring (not shown). A holding pin 124 permits the tensioning of the lever member 122 by being positioned against one side of an abutment 126 and also permits the untensioning by the shifting beyond the abutment as indicated in the previous embodiment. In this embodiment a cylindrical recess 130 is provided at the outer end of the rocker arm member 122. The other end of the rocking lever member 122 is provided with a bore 130 for mounting `a bearing bolt 128 which carries the tensioning roller (not shown). A partially ball-shaped joint piece 132 is positioned over the bolt shaft 128 and is positioned so that it contacts the walls of the bore 130. At a distance from the point piece 132 the bearing bolt 128 is provided with an abutment member 134 for the purpose of providing a rigid point which bears against the right-hand end face of the rocker according to FIG. 8.
This also insures that in spite of this engagement the bearing bolt 128 can be rocked in each direction. The end portion of the rocker member 122 is provided with a surface 136 which is partially 'ball-shaped. At this surface the abutment member includes a curved or ball-shaped inner portion 138 which bears over the projection 136. The bearing bolt is guided by means of -a pin 140 which is arranged in the rocking lever member 122 in an elongated slot 142. By means of `an adjusting spindle (not shown, but comparable to the other embodiments), the pin is biased so that the bolt -shaft 128 is urged to the left, as indicated in the drawings.
In FIGS. 9 and 9u another embodiment of means for mounting the bearing bolt -for the tensioning roller is shown. A rocker 152 is rotatable on a bearing pin 150 and it carries a pivotal pin member 156 which is supported in a bore of the rocker member 152 by a projection 158. The outer end of the pin member is provided with a fork 154 which carries a horizontal pin 171 at its outer ends. The bolt shaft or axis 162 for the tensioning roller is arranged in a bearing piece which is pivotally supported by the pin 171. The rocker 152 is fitted with two arms 15211 and 152b. In a threaded hole of the former a threaded spindle 172 is threadedly engaged which bears with its forward end 172a against the right hand end 'a (-see FIGS. 9 and 9a) of pin 171, which is held against said forward end 172a by means of a biased compression spring 170, said spring being with one end located in a hole of arm 152b and bears with its other end against the left hand end 171b (see FIGS. 9 and 9a) of pin 171.
By turning the threaded spindle 172 it is thus possible to change the cross-wise position of pin 171 and thus of the shaft 162 carrying Ithe tensioning roller.
Thus the invention provides an inexpensive sanding device with improved means for .adjusting the tensioning roller in a variety of ways. The tensioning roller may be shifted axially and rocked about its axis as well as displaced outwardly for tensioning purposes. Alignment of the belt is always assured by means of the guide rods which correct for any unbalancing forces by shifting the axis of the tensioning roller. While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.
I claim: l
'1. A belt sander comprising a casing, a driving motor supported centrally in said casing, a driving Iroller arranged at one end of said motor to be rotatably supported in said housing at one end of said motor and connected to -said motor for rotation thereby, a tensioning roller adjacent the opposite end of said motor, a rocking lever member pivotally mounted on said casing and Vhaving a free end extending centrally of said tensioning roller, a tensioning roller shaft, bearing means rotatably supporting said tensioning roller on said shaft, said rocking lever member having rocking bearing means -adjustably supporting said tensioning roller shaft within the tensioning roller for rocking adjustable movement, the rocking lever member being pivotal on said housing to permit movement of said tensioning roller outwardly for tensioning purposes.
2. A belt sander according to claim l, including means to bias said rocking lever member outwardly in a tensioning position.
3. A belt sander according to claim 2, including a tensioning relieving abutment defined on an end of said rocking lever member, a control pin held against rotation in respect to said rocking lever member and being axially displaceable out of the path of said abutment, said tensioning roller with said rocking lever member being displaceable by hand inwardly against said biasing force to permit positioning of said control means on the opposite side of said abutment, said abutment preventing said rocking lever member and said tensioning roller from being biased outwardly beyond a predetermined position.
4. A belt sander according to claim 1, wherein said means adjustably supporting -said bolt shaft includes a bore defined in said rocking lever member with an internal ball socket ledge portion, and a ball joint piece carried around said 4bolt shaft positioned in said bore and rotatably displaceable on said ball socket ledge portion, and means to bias said bolt shaft in a direction urging said ball joint piece into engagement with the ball ledge portion of said lever member bore.
5. A belt sander according to claim 4, wherein said means urging .said bolt shaft in-to engagement with the ball-shaped ledge portion of Said lever member bore includes first and second arms projecting on each side of said lever member, a bolt member extending through said ball joint piece on each side thereof in alignment with the arms of said lever member, spring means extending from one of said arms against said bolt piece and an adjustable pin member bearing against the opposite of said arms.
6. A belt sander according to claim 1, including a pin slidably mounted in said housing, said lever member being rotatably carried on said pin.
7. A belt sander comprising a housing, a driving motor secured to said housing, a driving 4roller connected to said motor for rotation thereby, a tensioning roller, a rocking lever member, axially movable means rotatably supporting said rocking lever member within said tensioning roller, a tensioning roller bolt shaft, said tensioning roller being rotatable on said bolt shaft, and means defined adjacent the free end of said rocking lever member rockingly supporting said bolt shaft.
8. A belt sander according to claim 7, wherein said means defined on said rocking lever member includes a bore having a ledge portion formed as a curved socket portion, a ball socket piece within said bore having curved portions in sliding engagement with the socket portion of said rocking lever member bore, s-aid ball socket piece being connected to said bolt shaft.
9. A belt sander according to claim 8, including a pin extending through said ball socket piece, said bol-t shaft having an elongated slot through which said pin extends.
110. A belt sander according to claim 9, including means for biasing said pin, in a direction urging said ball socket piece into engagement with the curved portion of said rocking lever member bore.
11. A belt sander according to claim 7, wherein said means rotatably supporting said rocking lever member within said tension roller includes a pin slidably mounted in said housing, and set screw means for xing said pin in a slidably adjusted position in said housing.
12. A lrocking lever member according to claim 7, including va guide rod member affixed to at least one end of said bolt shaft, including 4a portion extending in a curve around a portion of the circumference of said tension roller forming a guide for an endless sanding belt positioned over said driving roller and said tension roller.
13. A belt sander comprising a housing including a side bearing support wall portion, a driving motor secured to said housing, a driving roller connected lto said motor for rotation thereby, a tensioning roller, a pin slidably but non-rotatably mounted in said housing, a rocking lever member rotatable on said pin, spring means urging said rocking lever member lto rotate in a direction away from said driving roller, a tension roller bolt shaft, said tension roller being rotatable on said bolt shaft, and means defined adjacent the free end of s-aid rocking lever member and on said bolt shaft rockingly supporting said bolt shaft on said lever member.
14. A belt sander according to claim 13, including a control pin slidable in said pin and having ya portion bent at the inner end thereof at right angles to said pin, guide means on the exterior of said pin at an angle to the axis thereof, the control pin being held by said guide means against rotation relative to said pin but being displaceable out of said guide means, an abutment defined on said control lever member and preventing said spring means from moving said rocking lever member lfully outwardly when said control pin is positioned on one side thereof, said control pin being displaceable out of said guide means to permit positioning thereof on the opposite side of said abutment `and to permit said spring means to urge said rocking lever with said tensioning roller fully outwardly in a belt tensioning position.
l5. A belt sander according to claim 13, including a guide rod connected -to said bolt shaft adjacent at least one end thereof, and including a curved portion extending around a portion -of the circumference of said tension roller, said guide rod being adjustable to permit the outer curved end thereof to be located at a preselected height outwardly from the periphery of said tension roller.
16. A belt sander according to claim 13, wherein said means defined onsaid bolt shaft and said lever member includes ball and socket joint means supporting said shaft in said lever member. j 17. A belt sander according to claim 16, including a pin extending through said ball and socket joint means, and means biasing said pin in a direction toward engagement of the ball and socket joint means.
References Cited in the file of this patent UNITED STATES PATENTS