US2617457A - Power actuated toggle clamping fixture - Google Patents

Description

Nov. 11, 1952 c. H. WARWICK 2,617,457

powsa ACTUATED TOGGLE CLAMPING FIXTURE F11 00%. 30, 1948 2 SHEETS-SHEET 1 67 6'9 INVENTOR. 0 Ckor/ee H. Warm/bk 45' Nov. 11, 1952 c. H. WARWICK 2,617,457

POWER ACTUATED TOGGLE CLAMPING FIXTURE Filed Oct. so, 1948 2 SI-lEETS-SHEET 2 i INVENTOR. C/mr/es' h or'wick Patented Nov. I1, 1952 oFFIC-Ef POWER ACTUATED TOGGLE CLAMIPING FIXTURE Charles H. Warwick, Portland, Oreg.

Application October 30, 1948, Serial No. 57,505

2 Claims.

The present invention comprises a clamping machine of the type commonly called a door press. The principal purpose of the machine is to drive cross pieces into proper relation to the vertical members of doors or similar articles such as Window frames, ladders, or articles of furniture.

A further object of the present invention is to provide a machine which will press articles of the type disclosed to a definite limit regardless of the character of the wood employed. A disadvantage of previously devised machines is that such machines are designed to bring a pair of clamping members toward each other until the clamping members are arrested, either manually or by automatic trip means, whereafter the motive means is reversed and the clamps are drawn apart. The movable clamp remained at its innermost position for a relatively long time, with the result that some pieces tended to be compressed or sprung relative to other pieces employed in manufacturing an article. It is customary to provide doorsof standard widths, and all carpenters make frames to accommodate these standard widths. If the doors vary from standard, a great deal of time and material will be wasted since the door frame must be adjusted or changed, or the edges of the door planed down to fit. With the present invention the clamping members are brought toward each other to the desired limit and are immediately retracted so that the maximum pressure is applied only instantaneously and soft woods do not have a chance to spring.

A further object of the present invention is to provide a clamping machine of the character described in which one of two clamping members remains stationary so that the operator of the machine may remain in a single position, thus relieving the operator of considerable extra labor required with some machines as he steps forward and backward following the movable clamping element.

A further object of the present invention is to provide a clamping machine of the character described in which the stationary clamping member may be rapidly and accurately adjusted in position so as to accommodate articles of different widths.- In a door assembling plant the cross members are provided with adhesive at their tips and are partially inserted into the upright members by manual labor, being driven home to such an extent that the door may be handled as a unit. When the plant is manufacturing many different widths of doors at the same time it is necessary to press several of one size, then several of another size, and so on, so as to prevent a pile-up at each assembly station, or to provide a. plurality of clamping machines, one at each assembly station. One of the objects of the present invention is to eliminate a number of machines by making one machine instantaneously adjustable to accommodate all sizes.

A further object of the present invention is to provide a clamping machine in which the operation of drawing the clamping members together and retracting them is achieved while the motive means continuously functions in one direction of rotation. It has been attempted heretofore to provide electrically driven clamping machines of the character described, and several such machines are available. In all of these machines the clamping means is driven toward the clamping position while the motive means rotates in one direction, and then the motive means is reversed to retract the clamping means. This results'in one of two drawbacks. First, if automatic trip means are employed to stop the clamps at their limit of clamping and then to retract the clamps, the motors so employed may be burnt out in short order since the rapid reversal of field current results in overheating and overloading of the windings. On the other hand, if manual means are employed to reverse the motor, or a time delay relay is employed to insure a time lag between operations in reverse directions, the production of the plant is materially reduced. An object of the present invention therefore is to provide means whereby the motor is operated in one direction to project and withdraw the clamps, then is permitted to remain at rest while the clamped article is removed and a fresh assembly inserted, and is then operated in the reverse direction to move the clamps through a complete cycle.

A further object of the present invention is to provide a clamping machine of the character described which is entirely automatic in operation and which may be entirely operated by its own electric motive means. In most woodworking plants a central steam generator or air compressor is employed and various types of equipment are driven by servomotors, steam engines, or shafts and belting. An object of the present invention is to provide a clamping machine which may be operated as an independent unit positioned in localities too remote from the central plant to be practical for central plant operation. At present almost any locality may have current wired thereto, and the present invention is there and which will increase production of the plant and reduce the labor cost involved in producing clamped articles.

The objects and advantages of the present invention will be more readily ascertained from inspection of the following specification taken in connection with the accompanying drawings wherein like numerals refer to like parts throughout, while the features of novelty will be more distinctly pointed out in the appended claims.

In the drawings Fig. 1 is a plan view of a machine embodying the present invention;

Fig. 2 is a rear elevation of the machine;

Fig. 3 is a side elevation of the machine; and

Fig. 4 is a schematic wiring diagram.

The machine comprises a suitable frame including end supports l and heavy channel bars H mounted at the top of the supports. Ways l2 extend along the top of channel bars H and provide means for guiding the movable clamping bar l3 and the adjustably stationary clamping bar 14. The bar 13 is provided with a vertical face plate I?) for engaging the edge of an article supported on tongues I5 and the bar it is provided with a vertical face plate 51 for engaging the edge of an article supported on tongues [8, As is customary in such machines, rolls :9 may be provided to facilitate insertion and withdrawal of articles, and the face plate It is preferably shiftable longitudinally, being backed by rollers 26 and restrained toward the centered position by springs 2| so that a door or the like which has been manually assembled in a slightly skewed relation will be forced square as the clamps move together and the face plate [5 shifts in either direction.

The movable bar is is shifted by means including a pair of togg es and a floating. toggle screw. The toggles comprise arms pivotally connected to bar 53 and arms 25 pivotally connected to a cross frame member 27'. The toggle joints comprise pins 28 which project upwardly through slots 29 in a floating frame there being corresponding lower pins projecting through corresponding slots (not shown). The ends of the frame are slidably guided in ways mounted on end pieces 38 so that the frame moves exactly parallel to the. clamp bar. l3, the extent of movement of the frame as being half that of the movable bar it. The pins 28 are mounted upon nuts 35 which form supports for inner ends of the toggle arms. The nuts threadedly engage right and left-hand screw threads on the opposite ends of a toggle operating shaft 36 which is supported in a central bearing 37 mounted in frame 38 and end bearings 39 mountedin frame 35. One end of the shaft 36 projects through its end bearing, and a double sheave pulley ti! aifixed thereto is driven by belts M whichpass around a motor pulley fixed to the shaft of a reversible motor e3 mounted directly beneath the movable frame as when at the center of movement thereof. A drive of this type will operate efiiciently whilethe pulley 38 shifts laterally to the slight extent necessary. When the motor is energized to rotate in one direction the toggle arms will be shifted from the extreme angular position shown in Fig. 1 to the opposite extreme angular position, the clamping bar l3 being moved to its furthest extent as the arms 25 and 26 become aligned, and then being retracted'back to the position illustrated: in Fig. 1. When the. motor is driven in the opposite direc- 4 tion the clamp bar I3 is again fully extended and retracted.

It is preferred that the motor be arrested instantaneously when deenergized so that the maximum space will be available for insertion of the succeeding article, and for this reason the motor is preferably provided with a braking device 45. Many such devices may be utilized, one such being schematically illustrated as comprising a pair of brake shoe arms thrust toward braking position by a lever 38 and suitable spring means (not shown) and separated by a solenoid 41. Details of the device are not illustrated since many such are available and well known in the art. A further advantage or" having a braking device is that in the event an accident should occur, as, for example, a workman becoming pinched between the face plate and an article being clamped, the operator may instantly arrest the machine and, by means hereinafter described, cause reversal of the machine, thus possibly preventing serious injury.

A control circuit is schematically illustrated herein. The control circuit comprises a pair of limit switches 58 and 5!. The limit switch is contained in a limit switch box 52 having a switch operating roller arm 53 extending therefrom, and the switch 5| is contained in a similar box 552, having a similar roller arm 55 extending therefrom. The roller arms normally project toward each other under the influence of spring means (not shown), in which positions the switches 55! and 5! remain closed. The switch boxes are mounted upon the frame 36 near the extremities of one of the slots 29 with the rolloverhanging the slot in position to be ened by the toggle pin 28. Therefore, whenever the is between its extreme positions a circuit will be completed as follows: The motor es is connected across the line, as seen in T i, and comprises a field winding 56 and resing switch With both switches closed and he r versing switch as shown, the field is excited 37 current from one side of the line 69 through v itch from bottom to top of field 58 through witch 5i and line 59 to the opposite side of suply "5. When the'pin 28 strikes the roller on 53 switch 553 will be opened to break the ircuit and arrest the motor. The field winding o5 is in parallel with the solenoid 4'! so that the brake is held open as long as the motor is operated, but when the switch 58 is opened the brake will be applied to arrest the motor at its limit position.

In order to start the motor on the next cycle, one of a pair of treadles projecting from a control box G6 on the fioor near the operators station may be depressed. Each pedal operates a switch in parallel with one of the limit switches. In this case, switch 57 is closed to bridge the gap created by the open switch as, and switch 68 need not be operated since the line is closed at that end by switch 5%. The pedals 65 are located adjacent the field reversing switch 5? so that when either or both of'the pedals are depressed the switch E3? is moved from one position to the other, such devices usually comprising over-travel dogs or the like and being so common that details thereof are not illustrated herein. Thus, when the pedal 65 is depressed the direction of current flow through the motor field is reversed and current starts to flow from top to bottom'of the field when the switch 51- is closed. The pedal may be released practically instantaneously since the. pin 28 practically instantaneously releases the switch arm to permit switch 50 to close. Such devices may be adjusted so that a movement of A of an inch, or the like, will suffice. The motor will now operate until switch 5| is opened by pin 28.

It is to be noted that it makes no difference whether the operator makes a mistake in selecting pedals. If the wrong pedal is depressed the corresponding switch will not cause the motor to function and the reversing switch will not be reversed since it is already in the position to which the pedal Would have moved it, hence the operator immediately knows that he must depress the other pedal. On the other hand, if it becomes necessary immediately to arrest the machine and cause its reversal while the machine is moving toward clamping position, the operator need not take care to select the right pedal but may step on both of them, with the result that the reversing switch will be reversed and the motor immediately started in the opposite direction of rotation. Such action is extremely hard on the motor windings, but is permissible in the event of an emergency of the character which could arise in the operation of such equipment. It is, of course, desirable that such equipment should have other safety devices such as are commonly found in the art, but it does no harm to have the additional safety device provided by the herein described circuit.

In order to accommodate the machine instantaneously to operate upon articles of different widths, the adjustably stationary clamping bar 14 is provided with an index point which travels along a scale H fixed on one of the ways. On the opposite side of the way there is provided a reversing motor controller 12 comprising a switch arm 13 which may be thrown in either direction from a neutral position to cause operation of an adjusting motor 74 in one direction or the other. The motor 74 supports a pulley 15 driving belts IS which pass about a pulley 11 on a shaft 18 extending parallel to the clamping bars. The ends of the shaft 18 are connected through worm gear means 89 to a pair of transverse adjusting screws 8l. The rear ends of the screws 8! are mounted in fixed bearings 82 sup ported on the frame. Lugs 83 depending from the ends of the movable bar l3 embrace smooth portions of the screws BI and thus provide additional guiding means to maintain the alignment of the clamping bars. The threaded forward ends of the screws engage threaded lugs 84 depending from the ends of the bar M. A brake device 85 is mounted upon the shaft 78 and includes a movable strap adapted to be moved into braking engagement upon depression of a foot treadle 86. The operator may adjust the position of the movable bar by throwing the switch arm 13 in either direction and employing the brake to prevent over-travel when the switch arm is thrown back to neutral.

Having illustrated and described a preferred embodiment of the invention, it should be apparent to those skilled in the art that the invention permits of modification in arrangement and detail. I claim as my invention all such modifications as come within the true spirit and scope of the appended claims.

I claim:

A clamping machine of the type adapted to drive cross pieces into proper relation to uprights of wooden doors or similar articles, comprising a relatively stationary clamping member, a relatively movable clamping member, and means for reciprocating said movable clamping member toward and away from said stationary clamping member comprising a pair of toggle arms which when aligned with each other lie in the direction of movement of said movable clamping member, stationary means pivotally supporting the outer end of one of said toggle arms, means pivotally attaching the outer end of the other toggle arm to said movable clamping member, a nut pivotally supporting the inner ends of both toggle arms, a floating screw extending through said nut and having its longitudinal axis extending normal to the direction of movement of said movable clamping member, means to guide said screw for bodily movement in the direction of movement of said movable clamping member, said screw having a continuous thread extending in both directions from a line through the outer ends of said toggle arms, reversible driving means to rotate said screw, and limit means to arrest rotation of saidscrew when said nut arrives at either of two extremities of movement equidistantly spaced from a central position reached when said toggle arms are aligned whereby continuous rotation of said screw in one direction causes advance of said movable clamping member toward said stationary clamping member and immediate retraction and arrest thereof at its starting position.

2. A clamping machine of the type adapted to drive cross pieces into proper relation to uprights of wooden doors or similar articles, comprising a' relatively stationary clamping member, a relatively movable clamping member, and means for reciprocating said movable clamping member toward and away from said stationary clamping member comprising a pair of toggle arms which when aligned with each other lie in the direction of movement of said movable clamping member, stationary means pivotally supporting the outer end of one of said toggle arms, means pivotally attaching the outer end of the other toggle arm to said movable clamping member, a nut pivotally supporting the inner ends of both toggle arms, a floating screw extending through said nut and having its longitudinal axis extending normal to the direction of movement of said movable clamping member, means to guide said screw for bodily movement in the direction of movement of said movable clamping member, said screw having a continuous thread extending in both directions from a line through the outer ends of said toggle arms, a reversible electric motor operatively connected to said screw, and limit means operated by said nut to arrest said motor when said nut arrives at either of two extremities of movement equidistantly spaced from a central position reached when said toggle arms are aligned whereby continuous rotation of said screw in one direction causes advance of said movable clamping member toward said stationary clamping member and immediate retraction and arrest thereof at its starting position.

CHARLES H. WARWICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 874,406 Johnson Dec. 24, 1907 1,451,344 Robinett Apr. 10, 1923 2,321,644 Billstrom et al June 15, 1943

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