US2876600A - Sanding machine - Google Patents

Description

March 10, 1959 R. F. PENDERGAsv-T 2,876,600 SANDING MACHINE." I

3 Sheets-Sheet'l Filed Aug. 15, 1956 v INVENToR.

faF/VZYJ March 1o, 1959 A Filed Aug. 15, 1956 R. F. PENDERGAST SANDING MACHINE n 3 Sheets-Sheet 2 INVENTOR.

` Y BY m Afro/@wirf March 10, 1959 R. PENDERGAs-T 2,876,600

' SANDING MACHINE Filed Aug. 15, 195es sheets-Sheet' s SANDING MACHINE Raymond F. Pendergast, Robbinsdale, Minn. Application August 13, 1956, Serial No. 603,485

2 Claims. (Cl. 51139) My invention relates generally to sanding machines, -and more particularly to such machines utilizing a wide endless sanding belt entrained over a pair of spaced rolls and traveling at high speed to sand or otherwise treat a generally at surface of a workpiece fed through the machine.

. An important object of my invention is the provision of a sanding machine employing a power-driven feed roller, a power-driven contact roll in opposed relation to the feed roller, an idler roll, a sanding belt entrained over said contact and idler rolls, a novel means for mounting said rolls for movement of said contact roll toward and away from the feed roller and an interposed workpiece, whereby the contact roll will follow longitudinal varia tions in the contour of the belt engaged surface of the work -piece during travel thereof through the machine.

Another object of my invention is the provision of a machine as set forth, in which the Contact roll is yieldingly biased toward engagement with a workpiece being moved by the feed roller, and of novel means for varying the yielding bias applied to said contact roll whereby to accurately control the sanding action of the sanding belt upon the workpiece.

Still another object of my invention is the provision of a machine of the above type having a base frame and va rocking frame mounted on the base frame for rocking movements relative thereto, said rocking frame carrying the contact roll and idler roll, the contact roll overlying the feed roller and movable toward and away from the feed roller under rocking movement of the rocking frame, and of a shiftable control element movable in opposite directions to cause bodily movement of the contact roll toward or away from the feed roller.

t Another object of my invention is the provision of novel supporting means for said rocking frame and com-- prising primary and secondary pivot shafts respectively lat opposite sides of the rocking frame, the secondary shaft being releasably connected to one of said frames and removable therefrom to permit entrainment of the sanding belt over the contact and idler rolls.

Another object of my invention is the provision of a sanding machine as set forth having novel means for automatically and accurately maintaining the sanding belt against lateral creep relative to the contact and idler rolls over which the same is entrained, when running at high speed and under a work load.

Another object of my invention is the provision of a sanding machine of the type herein disclosed which is relatively simple and inexpensive to manufacture, which is highly efficient in operation, and which is rugged in construction and durable in use.

The above and still further highly important objects and advantages of my invention will become apparent from the following specification, appended claims, and attached drawings.

, Referring to the drawings, which illustrate the inven tion, and in which like reference characters indicate like parts throughout the several views:

, United States Patent y 2,876,600 Patented Mar. 10, 195.9.

Fig. 1 is a view in side elevation of a sanding machine built in accordance with my invention, some parts being broken away and some parts shown in section;

Fig. 2 is a view in top plan of the machine of Fig. 1, some parts being broken away;

Fig. 3 is a view in end elevation as seen from the line 3-3 of Fig. 1;

Fig. 4 is an enlarged fragmentary section taken sub stantially on the line 4-4 of Fig. 1; and

Fig. 5 is an enlarged fragmentary detail in section, taken substantially on the line 5-5 of Fig. 1.

Referring. with greater detail to the drawings, thenumeral 1 indicates, in its entirety, a relatively stationary or fixed base frame comprising, abase plate 2, a pair of elongated opposedside frame members 3 and 4, and front and rear-end frame members 5 and 6 respectively. Preferably, and as shown, theside frame members 3 and 4 are of greater heightythan the end frame members 5 and 6, and have journaled therein diametrically reduced shaft end portions of a plurality of workpiece supporting rolls which support a workpiece X during its travel through the machine' from the front to the rear-end thereof. A pair of such supporting rolls disposed toward the front end of the machine are indicated by thenumerals 7 and 8, and are provided with reducedshaft portions 9 that are journaled in theside frame members 3 and 4.

' Other supporting rolls toward the rear end of the machine are indicated at 10 and are provided with diametrically reducedshaft portions 11 that are journaled in theside frame members 3 and 4 in the same manner as theshaft portions 9 of the forward supportingrolls 7 and 8. As will hereinafter fully appear, thework supporting rolls 7 and 8 are power-driven to assist in feeding the workpiece X through the machine. With reference to Figs. l and 4, it will be seen that theshaft portions 9 of therolls 7 and 8 extend laterally outwardly with respect t0 theside frame member 4, and are provided at their outer ends withpulleys 12 by means of which the same are power-driven. A pair of work-engaging hold-down orpressure rolls 13 are disposed in overlying spaced relation, one each to one of therolls 7 and 8, and are provided at their opposite ends with diametrically reducedshaft portions 14 that are mounted for rotary and vertical movements in slots 1S of upwardly extending pairs ofbrackets 16 and 17, one each of which is welded or otherwise secured to the upper edge of each of theside frame members 3 and 4. Thebrackets 16 and 17 are of hollow construction, each containing ashoe 18 which engages and forms a journal for anadjacent shaft portion 14 of itsrespective pressure roll 13, and acap element 19 in upwardly spaced relation thereto.Coil compression springs 20 are interposed one each between eachshoe 18 and itsoverlying cap element 19. Anadjustment screw 21 is screw threaded in and extends downwardly to the interior of eachbracket 16, eachscrew 21 engaging arespective cap element 19, whereby to provide for variable spacing between therolls 7 and 8 and their respectiveoverlying pressure rolls 13. Thesprings 18 permit limited vertical movement of thepressure roll 13 whereby to allow a workpiece X having slight variations in thickness between its opposite ends, to pass therebetween. Preferably, the feeding and supportingrolls 7 and 8 as well as therolls 10 and 11 and thepressure rolls 13, are made from steel or like rigid material, whereby the workpiece X is rigidly supported during the sanding operation as will hereinafter become apparent.

Disposed between therolls 7 and 8, and in parallelv ment thereto from the front toward the rear end of tht;A

base frame 1. The opposite ends of the core 23 are diametrically reduced to provideshaft portions 25 and 26, the former of which is suitably iournaled in the side frame member 3, the latter being likewise journaled in the side frame member' 4. Thefeed roller 22 is driven by amotor 27, preferably of the type having a built-in speed reduction gearing, not shown, and transmission mechanism including a pulley 28 rigidly secured to theoutput shaft 29 of themotor 27, and an endless drive belt 3i) running over the pulley 28 and anotherpulley 31 fast on theshaft portion 26 of thefeed roller 22, see particularly Fig. 3. A pair ofpulleys 32, one of which is shown in Fig. l, are secured fast on the outer end of theshaft portion 26 outwardly of the adjacentside frame member 4, and are utilized to drive the rollers '7 and 8 through the medium of a pair of endless belts 33 and 34, one each running over one of thepulleys 32 and a respective one of thepulleys 12.

Disposed in overlying relation to thexed base frame 1 is a generally rectangular rocking frame, indicated in its entirety by thenumeral 35, andV comprising, a pair of laterally spacedparallel side elements 36 and 37 which are generally horizontally disposed, and which extend generally longitudinally of thebase frame 1, a cross bar 38 andtransverse brace bars 39 and 40. The cross bar 38 is preferably welded at its opposite ends to theside elements 36 and 37 adjacent the rear ends thereof, while thebrace bars 39 and 40 are bolted or otherwise rigidly secured at their opposite ends to the intermediate portions of theside elements 36 and 37. A relatively large diametenpreferably rubber covered,contact roll 41 is disposed between the front end portions of theside elements 36 and 37 of the rockingframe 35, and is provided at its opposite ends with reduceddiameter shaft portions 42 and 43 which are respectively journaled in theside elements 36 and 37. Thecontact roll 41 is disposed in opposed overlying spaced parallel relation to thepowerdriven feed roller 22, see particularly Fig. 1. At the rear end portion of the rockingframe 35, `anidler roll 44, of considerably less diameter than thecontact roll 41, is disposed in substantially parallel relationship to thecontact roll 41. Theidler roll 44, at its opposite ends, isprovided with axially extending reduceddiameter shaft portions 45 that are iournaled in supportingarms 46 at opposite ends of a bifurcated mounting element oryoke 47. Theyoke 47 is mounted on the cross bar 38, for pivotal swinging movements about a generally vertical axis, by means of a pivot bolt or the like 48 that is screw threaded into the cross bar 38. The intermediate portion of theyoke 47 is provided with an arcuate slot 49 concentric with the axis of thepivot bolt 48 and through which extends a retainer pin or bolt 50 that is screw threaded into thecross bar 35, said slot 49 and pin or bolt Si) cooperating to limit pivotal movement of theyoke 47 about the axis of thepivot bolt 48. A coil compression spring 51 is interposed between one end portion of theyoke 47 and the adjacent end of the brace bar 4G to yieldingly urge theyoke 47 in one direction of its pivotal movement. An adjustment screw 52 extends generally longitudinally of the rockingframe 35 and is screw threaded through the opposite end portion of the brace bar 40, and has abutting relationship with the end portion of theyoke 47 opposite the spring Si., whereby to move theyoke 47 in the opposite direction of its swinging movement against yielding bias of the spring 51. Thus, when an endless exible sanding band or belt, indicated by thenumeral 53, is entrained over thecontact roll 41 and theidler roll 44, manipulation of the adjustment screw 52 will cause thesanding belt 53 to properly track over the Contact andidler rolls 41 and 44 respectively.

The rockingframe 35 is mounted on the relativelyfixed base frame 1 for pivotal movements o-n a horizontal axis extending parallel to the axes of thefeed roller 22 and thecontact roll 41 and theidler roll 44, by means of a relatively large diameter primary pivot element S4 journaled in a xed bracket 55 welded or otherwise secured to the upper edge of the side frame member 3 of thebase frame 1, and a smaller diameter secondary pivot element or shaft S6 mounted in abracket 57 operatively associated with theside frame member 4 of thebase frame 1. As shown in Figs. 1 and 2, thebracket 57 is mounted for vertical sliding movements in a guide frame 58 that is welded or otherwise secured to theside frame member 4. An adjustment screw S9 is screw threaded through the bottom portion 60 of the guide frame 58 and extends vertically into abutting relationship with the bottom of thebracket 57, and is manipulated to raise or lower thebracket 57 to cause proper alignment to be achieved between the axes of the feed ro-ller 22 and thecontact roll 41. Preferably, thepivot shaft 56 is removable from engagement with itsrespective side element 37 of the rockingframe 35 and thebracket 57 to facilitate removal of thesand ing belt 53 when the same is worn, and replacement thereof over the contact andidler rolls 41 and 44 respectively. Removal of thepivot shaft 56 from engagement with itsrespective side element 37 of the rockingframe 35, causes the entire rocking frame to be supported solely by the relatively large pivot element or shaft 54. Although not shown, the large primary pivot element or shaft 54 is capable of limited rocking movements in a vertical direction in the bracket 55 so as to permit raising and lowering of thebracket 57 to a very limited degree. This is accomplished by the use of a well-known self-aligning bearing, notshown, but interposed between the pivot shaft 54 and its respective bearing bracket 55. With this arrangement thebracket 57 may be raised or lowered ,to enable the machine to accommodate a workpiece X which may be of slightly greater thickness at one longitudinal edge portion than at theother thereof.

For the purpose of imparting rotary movement to thecontact roll 41 to cause thesanding belt 53 to move at relatively high speed with respect to the workpiece X being fed at relatively low speed through the machine, l pro.- vide adrive motor 61 and power transmission mechanism therebetween and thecontact roll 41, now to be described. The primary pivot element or shaft 54 is provided with an axially outwardly extending, diametrically reducedshaft portion 62 on which is mounted for rotation adrive pulley 63 including asheave section 64 and a smallermultiple sheave section 65. A secondmultiple sheave 66 is rigidly secured to the outer end of the contact roll shaft 42, and is operatively coupled to themultiple sheave section 65 by a plurality ofendless drive belts 67. A drive belt 68 runs over thesheave section 64 of thepulley 63 and another pulley 69 mounted fast on thel ing frame 35, the distance therebetween and the multiple sheave orpulley 66 remains the same in all positions of rocking movement of theframe 35. Hence, the need for special belt tightening means for thebelts 67 is virtually eliminated, and such tightening need only be done to compensate for wear.

Gravity bias is imparted to the rockingframe 35 forwardly of the axis of its rocking movement to urge thecontact roll 41 into operative engagement with the underlying workpiece X interposed therebetween and thefeed roller 22, by means of a pair of suitable elements in the i nature ofweights 71 that are mounted for longitudinal sliding movements one each on a different one of a pair ofguide rods 72 that extend longitudinally of the rockingframe 35. Theguide rods 72 are mounted in spaced parallel relation torespective side elements 36 and 37 of the rockingframe 35 by front andrear legs 73 and 74 respectively, that are rigidly secured at their lower ends to opposite end portions of theside elements 36 and 3 7, Although theguide rods 72 are shown as being upwardly spaced from theirrespective side elements 36 and 37 of the rocking frame, it will be appreciated that the front and rear guiderod supporting legs 73 and 74 may be disposed to project laterally outwardly from theirrespective side elements 36 and 37, whereby to facilitate removal or replacement of the sandingbelt 53. It will be noted further that shifting of theweights 71 forwardly with respect to the machine will increase the bias irnparted to thecontact roll 41 in the direction of the workpiece X while shifting of theweights 71 forwardly with respect to the machine will increase the bias imparted to thecontact roll 41 in the direction of the workpiece X while shifting of theweights 71 rearwardly will cause a decrease of said yielding bias. Hence, with this arrangement, an operator is enabled to adjust the pressure of the sandingbelt 53 upon the workpiece X to obtain the desired finish, and the amount of material to be removed from the workpiece X can be controlled with a high degree of accuracy. For the purpose of releasably locking theweights 71 in desired set positions on theguide rods 72, I provide releasable locking means in the nature of set screws or the like 75 screw-threaded into each of theweights 71, the inner ends of the set screws being engagable with portions of theguide rods 72 ex tending through central passages in theweights 71. For limiting downward movement of thecontact roll 41 and preventing the sandingbelt 53 from coming into contact with the feedingroller 22, l provide stop screws 76 which are screw-threaded through outwardly projectinglugs 77 on the front ends of theside elements 36 and 37. The stop screws 76 extend downwardly from thelugs 77 and are adapted to have abutting engagement with stop lugs or ears 78 which project rearwardly from thefront brackets 16. The stop screws 76 are utilized to positively limit the depth of cut made by the sandingbelt 53 into the material X. This is particularly important when sanding a workpiece X which has a very thin veneer surface to be sanded. When sanding such material it is desirable that the sandingbelt 53 engages the material of the workpiece X with an extremely light pressure. This, as above indicated, is achieved by the location of theweights 71 on theguide rods 72, and the maximum depth of cut is determined by the setting of the stop screws 76.

The sand inbelt 53 is preferably made from paper with abrasive material cemented or otherwise adhered to the outer surface thereof. The speed of themotor 61 and the characteristics of the power transmission mechanism therebetween and thecontact roll 41 are such, that the sandingbelt 53 operates at speeds between 3,000 and 6,000 linear feet per minute. Under a no-load operating condition of the machine, manipulation of the adjustment screw 52 is usually sufficient to cause thebelt 53 to track properly over thecontact roll 41 and theidler roll 44. However, when a workpiece X is introduced between thefeed roller 22 and the overlying belt-equippedcontact roll 41, an unbalanced system results, causing thebelt 53 to move laterally toward one end or the other of therolls 41 and 44. This is particularly true when a relatively narrow workpiece X is passed through the machine at one side or other of the longitudinal center of the sandingbelt 53. Moreover, the sanding belt, being made of relatively thin paper or the like, is caused to stretch to a limited degree over its work engaging area. This stretch being unevenly disposed over the entire area of the sandingbelt 53 also aids in causing the same to move laterally in the machine.

For the purpose of causing thebelt 53 to properly track over the contact and idler rolls 41 and 44 respectively when a work load is applied to the sandingbelt 53, I provide a pair ofelongated pulleys 79 that are journaled each on one leg of a pair of generally U-shaped supportingbrackets 80 for rotation on axes extending generally transversely of the rockingframe 35. Each of theU-shaped brackets 80 is pivotally secured to a different one of theside elements 36 and 37 of the rockingframe 35 for swinging movements about an axis extending generally longitudinally of the rockingframe 35. A

pivotal mounting for the U-shaped brackets is shown75 in Fig. 5, said pivotal mounting including a nut-equippedpivot bolt 81 extending through one leg of thebracket 80 and through a suitable mounting ear or lug 82, fast on its respective side element. With reference to Fig. l, it will be seen that the sandingbelt 53 defines an approach light A to thecontact roll 41 and a departure flight B therefrom. It will be further noted that thepulleys 79 are disposed in closely spaced relation to thecontact roll 41 and positioned to engage the relatively smooth under-surface of thebelt 53 in its approach flight A. v

If, for example, during operation of the machine, the sandingbelt 53 is caused to move from the left to the right with respect to Fig. 3, theright hand pulley 79 is caused to move from its normal dotted line positionof Fig. 5 to its full line position of Fig. 5, thus causing entrainment by thepulley 79 of a relatively wide portion of thebelt 53, and causing the same to move to the left with respect to Figs. 3 and 5. The pulley at the left hand side of the machine, as seen in Fig. 3, operates in the same manner to stop undue movement of the sandingbelt 53 in a left hand direction and cause the same to move to its central position of Fig. 3. Thepulleys 79 and mounting means therefor is disclosed, together with a complete description of the operation thereof in my co-pending United States application, Serial No. 481,808,

led January 14, 1955, now Patent No. 2,813,382, dated` November 19, 1957, and entitled Sanding Machine and Method of Preventing Belt Creeping. The structure of the pulleys and theU-shaped brackets 80 therefor differs. from that shown in my co-pending application, above identified, only in the construction of thebracketsy 80. In the present machine, I provide eachbracket 80 with a laterally outwardly projectingstem 83 on which lare mounted counterbalancing elements orweights 84. Theweights 84 are so located on their respective stems 82, that the mountingbrackets 80 and theirrespective pulleys 79 are maintained substantially in a state of equilibrium. Thus, a minimum of pressure applied to thepulleys 7 9 adjacent edges of the sanding belt A, when the same moves laterally from its normaltrack, is required to move the pulleys to their belt-entraining full line positions indicated in Fig. 5.

While I have shown and described a commercial ernbodiment of my sanding machine, it will be understood that the same is capable of modification without departure from the spirit and scope of the invention as dened in the claims.

What I claim is:

1. In a sanding machine, a relatively fixed base frame. means including a power driven feed roller journaled to said base frame for feeding a workpiece in a direction generally normal to the axis of the feed roller, a generally rectangular rocking frame, means including axially aligned primary and secondary pivots intermediate the ends of said rocking frame and mounting said rocking frame on said base frame for rocking movements ony an axis parallel to the axis of said feed roller, said pri mary and secondary pivots comprising primary and secondarypivot shafts respectively at opposite sides of said rocking frame, a contact roll journaled to an end portion of said rocking frame in overlying generally parallel spaced relation to said feed roller and movable in a generally vertical direction toward and away from said feed roller upon rocking movements of said rocking frame, an idler roll journalled at the opposite end portion of said rocking frame on an axis substantially parallel to the axis of said contact roll, a wide endless workengaging sanding belt entrained over said rolls, said rocking frame being yieldingly biased in a direction to urge the contact roll toward the feeding roller and interposed workpiece, and mechanism for imparting rotation to said contact roll, said mechanism comprising, a motor, drive pulley means coaxial with and adjacent said primary pivot and operatively coupled to said motor, and driving 7 connections between said drive pnlleyv means and said contact' roll, said secondary shaft being r'eleasably connected to one of said frames and being removable therefrom to permit entranment of said sanding belt' over saidE contact and idler roll.

2'. In a sanding machine, a relatively xed base frame, means including a power driven feed roller journaled to said base frame for feeding a workpiece in a direction generally normal tothe axis of the feed roller, a generally rectangular rocking frame, a primary pivot intermediate the ends of said rocking frame at one side thereof mounting said rocking frameV on said base frame for rocking movements on an axis parallel to the axis of said feed roller, a secondary pivot comprising. ak pivot shaft at the opposite sideI of said rocking frame in axial alignment with said primary pivot, a supporting, bracket for said secondary pivot shaft, means defining guide- Ways on said base framev mounting said supporting bracket for movements relative to said base frame to move said secondary pivot shaft toward and away' from axial alignment with said primary pivot, adjustment means for imparting said movementto` said supporting bracket', a contact roll journaledL to one end portion ot' said rocking frame in overlying generally parallel spaced relation to said feed roller and movable in a vertical direction to'- Ward and awayl from said feed roller upon rocking move'- ment's of said rocking frame on the axis of said pivots, an idler roll journalled at the opposite endl portion of said rocking frame on an axis substantially parallel to the axis of said Contact roll, a Wide endless work-engagingy sanding belt entrained over said rolls, said rocking frame being yieldingly biased in a direction to urge the contact roll toward the feeding roller and interposed workpiece, and mechanism for imparting rotation to said contact roll, said mechanism comprising a motor and driving connections between said motor and contact roll.

References Cited in the tile of this patent UNITED STATES PATENTS 1,100,801 Wendell June 23, 1914 1,437,414 Gruenhagen Dec. 5, 1922 2,012,163 Gauld Aug. 20, 1935 2,257,305 Nickerson Sept. 30, 1941 2,507,372 Emmons May 9, 1950

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