US2373567A - Bending of boards - Google Patents

Description

April 10, 1945- J. w. JACKSON 2,373,567

BENDING 0F BOARDS Filed Oct. 16, 1942 2 Sheets-Sheet l NIW" April 10, 1945 J. w. JACKSON 2,373,567

BENDING OF BOARDS Filed Oct. 16, 1942 2 Sheets-Sheet 2 Patented Apr. 10, 194.5y

UNITED STATES PATENT OFFICEK Application October 16, 1942, SerialNo. 462,283

` 11 Claims. (Cl. 1411-268) The present improvements relate to the bending of boards, such for example as plastic sheets, plywood, composition boards, etc. A primary object served by. this invention is the production in such a board of bends which are accurate, de-

pendable, enduring, safe and smooth, by a simple and inexpensive apparatus, as will be hereinafter described.

A hardbcard usually incorporates in its structure numerous bers which are susceptible to breaking or splitting if the board be bent through a relatively short radius. For this reason aswell as others the bending of hardboard has generally been considered as presenting special problems. These diiculties commonly arise through the employment of long standing bending practices which have undergone little, if any, changes over a period of many years. The application of the usual heavy pressureLsuiiicient to force a frictional bending of the material, is often detrimental in the treatment of composition boards, for example, consequently I prefer to employ an altogether diierent and frictionless principle of operation.

According to the present invention, the board to be bent may be either dry or wet. For the bending operation I utilize a roll, circular or otherwise, about which the board is wrapped, the roll being either cold or heated. It is desirable, however, particularly to facilitate and expedite operations, that the roll be heated and that the board be wet. A point of primary importance is the application of the force which operates upon the board to produce the bend. I find it satisfactory to employ for this purpose a roll having a radius the same as, or very slightly less than, the bend desired for the board, and then, after clamping the board to the roll, advance the roll along the board for a distance commensurate with the bend that is desired. In this operation the roll axis executes a linear movement, and the roll need not be mounted within any bearings, xed or otherwise.

. Boards which are bent in accordance with the ensuing description may be used for many pur- DOSes, some of which have heretofore been served regularly by sheet metal. One example is a pipe, requiring va. bend of 360 or more. Another example is a reflector for uorescent lights. Two bends, each something less than 90, are usually formed in such a reflector, the two regions of bend being separated from each other and from the edges of the board. These are two convenient examples of use to which a bent board may be put. The apparatus herein shown and described is designed with particular reference to the production of one or more bends in a board which may serve in any such capacity.

In the drawings:

Figure 1 is a central sectional view through the machine, lengthwise thereof, showing the bending roll in its initial position of rest;

Fig. 2, which is a similar View, shows the bending roll in its inal position wherein a bend has been imparted to the board;

Fig. 3 is an enlarged detail in section taken on line 3 3 of Fig. 1;

Fig. 4 is an end elevation of al bending roll equipped with a modification in the weight mechanism;

Fig. 5 is .a top plan view of the machine as shown in Figs. 1 and 2;

Fig. 6, which is a. view similar to Fig. 3, shows a modification in the clamping bar;

Fig. 7 is a View generally similar to Fig. 1 wherein the machine is shown as vertically rather than horizontally disposed;

Fig. 8 is a view, partly in elevation and partly in section, of a duplex machine in which two bends may be produced simultaneously; and

Fig. 9 is a transverse sectional view of a ma- A chine of modified construction.

In employing the present apparatus, for 'bending of composition boards, known generally as hardboard it may be desirable, although not necessary, to first wet the board as with water, oils, thermo-setting synthetic resins, or other softening or reactive agents. While'performing a bend, I am careful not to force the board. Instead it is subjected to a frictionless pressure, constantly and perhaps variably applied, and exerting always a persuasive force, tending to bend the board at a rate which varies with the willingness of the board itself, at each successive point, throughout the region where bending takes place. A bend so performed may proceed relatively slow or fast, and also at variable speeds, depending upon the willingness of the board at each point which is subjected to the bending strain, and because of this peculiar relationship between the applied force and the board resistance, breaking, splitting or rupturing of the board in the region of its bend is avoided.

In the machine shown in Figs. l-3 and 5, I employ a horizontal table whose top T provides a heat-resistant support whereon a board B may be freely rested. lNear the edges of this table top are placed a pair of spaced stops Il) adjustable vertically or horizontally of the table in whose top may be formed, in one end region thereof, a

crosswise recess for receiving in ush relation a pair of anges II extending horizontally from two depending angle plates with an electrical heating element l2 therebetween. Heat conducted to the anges is thereby transmitted to the overlying board B in its end region where bending is to take place.

Upon a. table so constructed is placed a bending roll R which may be a pipe or tube having a radius approximately the same as that desired for the bend to be imparted to a board. The roll whose axis is movable is positioned with its axis crosswise of the table, the roll ends being desirably extended beyond the sides thereof (see Fig. 5). In its initial position the roll abuts a pair of blocks I4, as shown. A clamp C, here shown as an angle bar, is tted to the roll lengthwise thereof, being securedV thereto near opposite ends thereof with bolts l5, arranged in pairs, the bolts passing through spacer plates I6, affixed to the roll adjacent the ends thereof, whereby the clamp is maintained in a fixed spaced-apart relation to the roll a distance somewhat greater than the thickness of the board which is to be operated upon (see Fig. 3). Also cai'ried by the clamp is a pair of gauges I1, each adjustable in a direction lengthwise of the table (when the roll is in the initial position of Fig. 1), and formed with an upturned finger I8 against which the board may abut when advanced into operating position in the space beneath the roll and above the clamp.

By shifting these gauges to move the fingers toward or from the table the board may be accurately positionedto receive a bend which starts close toits end, or at a distance which is removed therefrom, the arc or extent of the bend being determined by the distance through which the roll is thereafter permitted to advance before the stops l 0 are engaged.

It is often desirable that the roll be heated, a suggestive means for this purpose being the pipe 20 that is axially mounted within the roll, the pipe walls being formed with numerous radial ,openings through which gas may escape to be burned in the form of flame jets which will impart heat to the surrounding roll. A flexible connection 2| (see Fig. 4) leads from a gas supply to the pipe for delivering fuel thereinto. To utilize gravity force for advancing the roll I may employ any one of several expedients one of which, shown in Figs. 1-3 and 5. comprises a pair of co-planar rods 22 extending radially from the roll and rotatable relative thereto. each rod supporting an off-center weight 23 adjustable lengthwise thereof. The direction in which these rods are extended is preferably vertically upwardly when the roll is in its initial position of rest (see Fig. 1) wherein the clamp C engages the tops of a. pair of vertically adjustable swinging links 24. Each link 24 is pivoted at one end on a bolt 24 and on its opposite end carries a bolt 24a which has movement in the respective arcuate slot 24b and tightened in the slot by means of the respective nut 24c whereby to adjustably support the clamp C at one end of the table T. In the position illustrated, the preponderance of weight will be to the left of the roll axis, tending to hold it at rest. but when tle rods are turned around to opposite positions (see Figs. 2 and 5) the roll will tend to advance to the right in response to the gravity force exerted by the Weight preponderance to that side of the roll. The amount of the force so exerted may be controlled within wide limits by the adjusted radial positions of the weights relative to the roll. .An alternative de- 75 vice for utilizing gravity force is also suggested in Fig. 4 wherein the roll R is fitted at its ends with ilanged wheels 25 to each of which is fastened and extended therearound a flexible cord 26 which carries at its depending end a. weight 21. The roll in this case is also shown as mounting a pair of balanced .weights 28 whereby to increase the pressure with which it bears on the board undergoing treatment. These two expedients of utilizing gravity force for advancing the roll lengthwise of the board and for increasing its pressure thereupon are suggestive of many which are available.

In operation, a board is slipped into place while the roll is in its initial position where the vertical flange of the angle clamp is rested near opposite ends upon the vertically adjustable supporting plates 24 so that the roll will be maintained at the desired elevation. The board end then lies bet-Ween the roll bottom and the clamp therebelow so as to held thereby against the roll during advance thereof along the board lengthwise thereof. The weights employed for utilization of gravity force are suflicient to produce a slow persuasive movement of the roll against the yielding resistance offered by the board. During this movement the board wraps itself around the roll without friction to the extent 0f the roll advance which ceases when engagement with the stops ensues. In the form shown in Figs. l and 5 these stops lie in the path of the roll to be engaged thereby WhereasY in the showing of Fig. 2 the stops are supported in the path of the radius rods 22 to receive engagement therefrom. The bend thus imparted to the board will extend through the arc determined by linear advance of the roll, the region of the bend being iixed by adjustment of the gauges which determine the starting point, of the bend. Several minutes may elapse between the start and nish of this operation, the roll advancing slowly lengthwise of the board, and perhaps at a rate of speed which is variable depending upon the yielding resistance that is offered by the board.

The clamp which serves to hold the board against the roll may optionally be constructed as per Fig. 6 Where it is shown as a bar 30 removably secured at one end to a hook plate 3l which is affixed to the roll R, the opposite bar end being provided with a keeper 32 which extends transversely through registering openings in a spacer plate 33 and the wall of the roll to be engaged by a bolt 34 normally urged to locking position by a spring 35. This bolt may be supported in a block 36 that is aflixed to the inner face of the wall of the roll adjacent one end thereof so as to be convenient for manipulation. In practice the clamping bar which is thus removably carried by the roll may readily be detached therefrom when convenience will be served as, for example, when a board With an extended bend, or with a bend removed from its ends, is to be stripped from the machine.

Referring now to Fig. 7, I have here shown a very similar construction in which the board support T is vertical, beingV carried by a frame which comprises a vertical post 40 defining with the support a guideway in which the roll R is free to move through a vertical path. This roll is equipped with a suitable clamping bar C for engaging with the board B whereby to hold it against the roll during its descending movement in response to a requisite force, gravity or other# wise. The roll in this Vconstruction may be heated, as by gas delivered through a burner pipe 2U the same as already described, and in operation will perform the same as the rolls of Figs. 1-5.

A duplex machine for making two bends simultaneously in either the same board or in two different boards, is illustrated in Fig. 8. The parts employed in such a duplex machine may be the same as those already described and so bear corresponding reference characters, but they are to some extent duplicated so as to have capacity for operating upon two spaced-apart regions of the same board or upon two separate boards which are arranged edge to edge. It is necessary only to note that the two rolls advance toward each other to the limits which are determined by the stops, and that during the advance of each a bend is produced in the engaged board to the extent that it is wrapped around the roll.

A weight 23 carried on a radial rod 22 will obviously exert an increasing torque force on the roll through the first 90 of its advance. 'I'his'is desirable both because most commercial bends are less than 90 and because theapplication of a progressively increasing force is conducive to safest results. At the start the board willingness to yield is not so great as later, due probably to the fact that bending strains transmitted ahead to points of the board later to be bent will condition the board at such points for more ready yielding when finally subjected to the bending force imparted by the roll.

In Fig. 9 I have illustrated a bending roll R supported upon rollers 40 for rotation upon a fixed axis. A spring-pressed guide roller 4I adjacent the bending roll holds a board B tangentially thereagainst, its leading edge being secured by a clamp C which is carried by the bending roll. When relative movement takes place between the board and bending roll, produced either by applying a. torque force to the roll or a thrust force to the board, or both, the board will undergo a frictionless bend in the manner already set forth.

From the foregoing description, it will be noted that bending of a board involves (1)-tangential securement of the board to a bending roll, and (2) relative motion between the board and roll, in response to a gravity or equivalent force, such as to produce a wrapping of the board around the roll to the arcuate extent of the desired bend. Such a bend, when completedin a hardboard. will be permanent, and for ready stripping of the board only a reverse relative movement between the board and roll is-require'd.

I claim:

1. In a board-bending machine, means providing for the board a support against which the board may be rested,a bending roll advanceable along the board in engagement with one surface thereof, means connecting one edge of the board to the roll in parallelism with the axis thereof and adapted to hold the board closely against the roll during all stages of advance thereof, said connecting means initially constituting asupport portion in alignment with the said board support and movable out of alignment therewith as the bending roll advances along the board, and stop means for limiting advance of the roll through a fixed distance during which the board is Wrapped around upon the roll surface in conformity therewith and through an arc commensurate with its distance of advance.

2. In a board-bending machine, means providing for the board a support against which the board may be rested, a bending roll movably mounted above the board and advanceable along the board in full weight engagement with the upper surface thereof, a weight movably mounted upon the roll adapted in one position to dispose a preponderance of gravity force to one side of its axis and in an opposite position to dispose a vpreponderance of gravity force to the opposite side of its axis, means carried by the roll and engageable with the board to hold it closely against the roll during all stages of advance thereof, and stop means for limiting advance of the roll through a fixed distance during which the board is wrapped around upon the roll surface in conformity therewith and through an arc commensurate with its distance of advance.

3. In a board-bending machine, means providing for the board a support against which the board may be rested, a bending roll advanceable along the board in engagement with one surface thereof, a combined board gauge and clamp affixed to the roll for positioning and holding the board closely against the roll during all stages of advance thereof, said combined board gauge and clamp normally lying in abutting relation to and in the horizontal plane of the board support and movable upwardly out of said plane as the roll advances along the board, and stop means for limiting advance of the roll through a xed distance during which'the board is wrapped around upon the roll surface in conformity therewith and through an arc commensurate with its distance of advance.

4. In a board-bending machine, means providing for/the board a support against which the board may be rested, a bending roll advanceable along the board in engagement with one surface thereof, means removably carried by the roll env gageable with the board and constituting an extension of the board support and adapted with the yrotation of the roll to closely hold the board against the rollduring all stages of advance thereof and, upon removal, permitting free release of the board, and stop means for limiting advance of the roll through a fixed distance during which the board is wrapped around upon the roll surface in conformity therewith and through an arc commensurate with its distance of advance.

5. In a board-bending machine, a support together with a roll proximate thereto, the two being adapted to receive therebetween the board to be bent, a weight carried by the roll adapted in one position to dispose a preponderance of gravity force to one side of its axis and in an opposite position to dispose a preponderance of gravity force to the opposite side of its axis, and means carried by the roll engageable with the board at one end of the latter for holding the board tangentially at one linear point closely against the roll throughout the cycle of movement.

6. In a board-bending machine, a support together with a roll proximate thereto, the two being adapted to receive therebetween the board to be bent and to provide for relative movement between the roll and board, means carried by the rollengageable with the board at one end of the latter for holding the board tangentially at one linear point closely against the roll throughout the cycle of movement, and means adjustable in a direction substantially radially of the roll when in its initial position affording therefor a support at a desired point relative to the plane of the board.

7. In aboard-bending machine, means providing for the board a support against which the board may be rested, a bending roll mounted to roll along the board, clamping means secured to the roll and having a portion disposed normally in the plane of said supporting means to freely receive an edge of the board between the supporting means and the clamping means, and means whereby to advance the roll over and on the exposed face of the board and simultaneously shift said clamping means out of the plane of said supporting means in clamping relation with the roll to bind the board tightly between the clamping means and roll to bend the board.

8. In a board-bending machine including a movable roll and means whereby the said roll may be moved to bend the board, a clamping element substantially coextensive with the length of the roll and nxedly secured thereto adjacent each end of the roll and between its points of connection with the ends of the roll providing a space for the insertion of the board between the roll and the clamping element, said space between the roll and clamping element being substantially coextensive with the length of the roll whereby the end of the board to be bent is freely inserted into said space and projected beyond the said vclamping element, whereby upon movement of said roll the board is bent to conform to the shape of that portion of the roll that it engages during movement of the roll.

9. In a board-bending machine, means providing for the board a. support againstY which the board may be rested, a bending roll mounted to move on the board and advanceable along the board in full weight engagement with one sur face thereof, a combined board guage and clamp secured to the roll with the clamp normally in abutting relation with one end of said supporting means and with the clamp spaced slightly from the roll to provide a space for the free insertion of the board between the roll and clamp into engagement beyond the clamp with the outer end. of the guage, means whereby to move the roll and simultaneously shift the guage and clamp away from abutting relation with the supporting means so as to bend the board on the roll during all stages of advance movement of the roll, and means for limiting the advance movement of the roll.

10. In a board-bending machine, means providing for the board a support against which the board may be rested, means carried by the supporting means for heating the board mounted on the supporting means, a bending roll rotatively mounted to rotate on the exposed surface of the board and advanceable along the board in engagement with the exposed surface thereof, a combined guage and clamp secured to the roll with a portion of the clamp being substantially coextensive with the length of the roll and spaced slightly therefrom to provide a space to freely receive one edge ofthe board, the board being positioned between the roll and the clamp and having one edge in engagement with the outer end of the guage, a portion of the clamp forming an extension of said board supporting means and separable therefrom, means whereby to rotatively advance the roll along the board and simultaneously shift the clamp and guage away from the board supporting means and wrap the board around the roll to bend the same, and means for limiting rotative movement of the roll.

l1. In a board-bending machine, a supporting means for the board, a bending roll advanceable along the board in engagement with one surface thereof, and means to connect one edge of the board to the roll in parallelism with the axis thereof, including a combined clamping member and gauge secured to the roll, the gauge extending laterally from the clamping member beyond the roll and disposed normally in horizontal alignment with said supporting means and movable out of alignment withthe latter in the rear of the roll as the roll advances along the surface of the board. j

J. WILLIS JACKSON.

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