US3131926A - Systems for effecting pressure on presser feet for clamps or paper cutting machines - Google Patents

Description

May 5, 1964 c. THUMIM 3,131,926

SYSTEMS FOR EFFECTING PRESSURE ON PREssER FEET FOR CLAMPS 0R PAPER CUTTING MACHINES Filed Oct. 27, 1961 2 Sheets-Sheet l //4 INVENTOR.

C'fl/PL THl/M/M May 5, 1964 Filed Oct. 27, 1961 0/ L PUMP A/A? PUMP c. THUMIM 3,131,926 SYSTEMS FOR EFFECTING PRESSURE ON PRESSER FEET FOR CLAMPS OR PAPER CUTTING MACHINES 2 Sheets-Sheet 2 A rrd/P/v K United States Patent 3,131,926 SYSTEMS FOR EFFECTING PRESSURE 0N PRESSER FEET FOR CLANEPS OR PAPER CUTTING MACHINES Carl Thumim, Lombard, Ill., assignor to Miehle-Goss- Dexter, Inc, Chicago, Ill., a corporation of Delaware Filed Oct. 27, 1961, Ser. No. 148,177 8 Claims. (Cl. 269-24) This invention relates to paper cutting machines, and more particularly to the clamps thereof.

In a previously filed application of Carl Thumim, Serial No. 701,570, filed December 9, 1957, now latent No. 3,025,049, assigned to the present assignee, there is disclosed a clamp for a paper cutting machine having a plurality of presser feet. The clamp bar is operated by hydraulic pressure while the individual feet are subjected to pneumatic pressure. The purpose of such arrangement is to effect uniform pressure on a paper pile which may vary in vertical contour due to irregularity in thickness of sheets.

The present invention constitutes an improvement of the system disclosed in the prior application, in that it provides for effecting a floating condition of the presser feet with respect to the bottom of the clamp bar within predetermined Such an arrangement provides for complete flexibility and freedom of self-adjustment of the presser feet to the contour of the paper pile. However, where the length of the paper pile under the clamp may vary, the total :air pressure acting on the feet should likewise vary, to be equal to the total hydraulic pressure on the bar so as to ensure individual operation of the feet on the pile. This is of advantage where a paper pile is being out which may be greater in one dimension than in the other, and accordingly relieves the operator of the necessity for varying air pressure inversely with the length of the out as he rotates the pile 90 for cuts in different directions.

The principal object of the system disclosed herein is to overcome automatically the need for operator attention to air pressure, by effecting floating of the presser feet so that under normal operating conditions, with suitable pressure being supplied, the feet always remain controlledly spaced from the clamp bar when engaging the paper pile in order to exert properly their individual pneumatically effected pressures on the respective areas of the pile which they contact. Other objects and features of the invention will be apparent from the description to follow.

Briefly, the invention comprises a construction as generally shown in the aforementioned application, except that two lengths of so called Tapeswitch are utilized as sensing elements, one such Tapeswitch being disposed between the bottom of the clamp bar, rimming the length thereof, and the oppositely facing surface within each pressure foot. The other Tapeswitch is carried by the clamp bar in such a position that a depressible pin carried on a shoulder of each of the presser feet may engage it. Thus the arrangement provides for the two T apeswitches being so positioned that as the feet engage a pile, a normally open solenoid valve which bleeds from the presser feet pneumatic manifold is closed, thus to fix a maximum spacing between the clamp bar and the presser feet. On the other hand, the Tapeswitch within the presser feet is actuated when the bar arrives at a predeterminedly close position with respect to the presser feet, to effect opening of a normally closed valve for admission of air pressure to the manifold. Thus, the Tapeswitches operate in response to an upper or lower positional spacing limit of any presser feet, starting at the time such prwser foot engages the pile on the downward movement of the clamp and ending when sufficient air pressure is in the manifold 3,131,926 Patented May 5., 1964 (and the individual presser feet cylinders) to all feet clear of the bottom of the bar.

A detailed description now follows in conjunction with the appended drawing in which:

FIGURE 1 a side elevation in section showing the principal parts of the novel system herein as applied to a clamp bar having individual presser feet;

FIGURE 2 is a magnified detail of a portion of FIG- URE 1, and,

FIGURE 3 is a fragmentary elevation viewed from the front of the clamp bar.

Referring to the drawing, FIGURE 1 illustrates a crosssectional side elevation of a clamp bar 10 and a U-shaped presser foot '14 associated therewith. The presser foot is suspended as by the lost motion bolt arrangement 17, in a heretofore known manner, from the pending portion 20 of the clamp bar. A rod 23 passes through portion 20 and acts on the surface 25 of the U-shaped presser foot to transmit pressure from c. piston 28 within a pneumatic chamber 31 fed from a common manifold 34. A spring 37 biases the piston against the rod. The construction thus far described is substantially the same as disclosed in the aforementioned patent application, and it will be understood that the clamp bar 10 is hydraulically actuated as by an oil pressure cylinder while the manifold 34 is connected by flexible hosing indicated by the phantom line 38 to a source of air pressure 39.

On the base surface 40 of the clamp bar portion 20 there is a Tapeswitch T-l which will be understood to run the length of the clamp bar and to be engageable with the surface 25 of any of the presser feet 14 for purposes of closing a circuit to be hereinafter described. The Timeswitch may be secured any suitable manner and comprises a long fiat strip having a cover of tubular insulation containing conductive elements such that when pressure is brought to bear anywhere along the strip, a conmotion is made between local conductive elements at the point of pressure. Inasmuch as Tiapeswitch is a well known commercial product, no further detailed description is necessary.

A second Tapeswitch T 2 is secured below the horizontal wall portion 42 of the clamp bar and is engageable by any one of a series of pins 43 carried by respective presser feet, as shown in FIGURE 2, in one of the vertical walls thereof. Thus, each pin 43 is retained in a bore 46 in a respective vertical wall and spring biased as by spring 48 so that engagement between any pin 43 and Tapeswitch T-Z be resilient in nature and allow for movement of the clamp bar with respect to the presser feet.

The positioning of the T apeswitches is such as to effect a floating action of each presser foot for approximately the spacing indicated by the letter S of FIGURE 1, indicating the distance between the vertical arrow The surface 40 of clamp bar portion 20 represents the upper limit of free relative movement while surface 25 represents the lower of such movement. Of course, the ridge of the Tlape'switch and the bulk of the Tapeslwitch will subtract slightly from the degree of such movement in a downward direction of the clamp bar. However, if the Tapeswitch be disposed in a recess of clamp bar surface 40, then only the ridge thereof subtracts from the free distance.

In order to effect the above free floating function, the system comprises a normally closed solenoid operated valve 50 communicating with the air supply 39 and also communicating via tubing 38 to manifold 34, so that opening of the valve will permit air pressure to reach the manifold which feeds all of the presser feet cyclinders. The system also comprises a normally open solenoid operated valve 54 having an air bleed port 57 and connected as indicated by the phantom line 60 to the manifold. Thus, through valve 54 air can bleed from the manifold outwardly via port 57, unless the valve is energized to close position.

Finnally, a double-acting relatively fixed switch 64 is nections are made to the solenoid of valve E4 through QT-Zj shunted by contacts 64a. Thus contacts -ibserve as a conditioning switch for T1 and also ensure. air pressure cutoff when the clamp is at upper position in the event of malfunction of T-l.

In operation, assuming the condition shown in FIGURE 1, the circuit is broken to valve 59, which being normally closed, prevents any air passing to the manifold 34. Likewise, due to the shunting at contact 64 valve 54 is ener- I gized to closed position to prevent air loss by bleeding off of. air. from the manifold. 'Now, if the clamp moves downwardly switch 64 is released whence air starts to bleed slowly from the manifold through valve now de-energiz'ed, and assuming its normally open position. Continued downward movement of the clamp ultimately brings T-2 into engagement with any of the pins 43 which may'happen to strike a rising contour of the paper 'file. 'Thereupon closure of T-2 energizes valve 54 to close that valve and thus prevent further air bleed.' Assuming that the clamp bar continues its downward movement, T-l engages surface 25 to energize valve-5ll to its open position whereby air pressure flows to'the manifold and is operative inthe respective cylinders of the presser feet to force the presser feet downwardly, relative the clamp bar, in order to restore the spacing S. The effect of the overall system is to control the air pressure responsive to any presser foot engaging Tapeswitch T1 or T2, so as .to ensure all presser feet having vertical freedom of motion with respect to the clamp bar within the limits imposed by the distance S.

Having thus described my invention, I am aware that many changes may be made without departing from the spirit thereof, and, therefore, I do not seek to be limited to the precise illustration herein given, except as set forth in the appended claimsi it I claim:

' r 1. In a paper cutting machine, a clamp bar and a plural-. ity of individually movable presser feet carried thereby, and means for applying fluid pressure to individual. feet from a common manifold to effect uniform pressure on -a paper pile of varying contour, and position control means for maintaining respectivepresser feet between two limit- 7 ing positionswith respect to said clamp bar so as to ensure freedom of vertical movement with respect thereto between said two positions. p I

2. In a device as set forth in claim 1, said position control' means comprising sensing elements disposed intermediate said clamp bar and said presser feet. adapted to be engaged in respective upper and lower positions of said clamp bar with any of said feet, and fluid control means connected'to said manifoid and actuated in response to engagement of one of said sensing elements and operative to respectively admit or exhaust pressure from said manifold to maintain said feet between said limiting positions.

3. Inga device as set forth in claim 2, said sensing elements comprising two series of electrical switches and means whereby a switch of one series is actuated by av respective presser foot when said clamp bar and presser foot are in a predetermined maximum spacing condition when said foot is applying pressure to a pile, a switch of the other series being actuated when a respective presser foot approaches a predetermined minimum spacing when applying pressure to a pile.

4. In a device as set forth in claim 2, said fluid control means comprising a normally open bleed valve responsive to a disengaged condition of one of said sensing elements, to exhaust fluid from said manifold and operative to be closed when said sensing element is in engaged condition to determine the maximum spacing ofsaid clamp bar and said presser feet;v saidfluid control means also comprising a normally closed valve operative to open in response to engagement of the other of said sensing:

elements.

S. In. a device asset forth in claim 2, said sensing elements comprising first and second pluralities of electrical switches and means whereby a switch of first plurality is actuated by a respective presser foot WhBII SZld. clamp bar and presser foot are in a predetermined maximum spacing condition when saidfoot is applying'pressure to a pile, a switch of the second plurality being actuated" when a respective presser foot approaches a predetermined minimum spacing when applying pressure to said pile,

said fiuid'control means comprising a normally'open.

solenoid operated bleed valve responsive to disengaged condition of all of said first plurality of electrical switches to exhaust fluid from said manifold and operative to be closed when said any of said switches is in an engaged condition; said fluid control means further comprising a normally closed solenoid operative valve openable in response to engagement of any of the switches of said second plurality, and circuitry means connecting said pluralities of switches with said valves for effecting energi zation of the solenoids thereof.

6. In a device as set forthin claim 5, said fluid control means further including a switch in relatively fixed position and adapted to be engaged bysaid clamp bar when said clamp bar is in maximum raised position, said normally open valve beingoperative to be energized to closed position responsive to said engagement.

7'. in a device as set forth in claim 6, said latter switch having means to prevent deenergization of said normally closed valve when said switch is engaged by said clamp bar.

8. In a paper cutting machine, a clamp bar and a plurality of individually movable presser feet carried thereby for maintaining respective presser feet between two limitin positions with respect tosaid clamp bar so as to ensure freedom of vertical movement with respect thereto between said two positions, including hydraulic power means for actuating said clamp bar, said means for applying fluid pressure to said presser feet comprising a source of air pressure.

References Cited in the file of this patent UNITED STATES PATENTS 7 3,025,049 Thumin Mar. 13, 196;

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Claims (1)

1. 8. IN A PAPER CUTTING MACHINE, A CLAMP BAR AND A PLURALITY OF INDIVIDUALLY MOVABLE PRESSER FEET CARRIED THEREBY AND MEANS FOR APPLYING FLUID PRESSURE TO INDIVIDUAL FEET FROM A COMMON MANIFOLD TO EFFECT UNIFORM PRESSURE ON A PAPER PILE OF VARYING CONTOUR, AND POSITION CONTROL MEANS FOR MAINTAINING RESPECTIVE PRESSER FEET BETWEEN TWO LIMITING POSITIONS WITH RESPECT TO SAID CLAMP BAR SO AS TO ENSURE FREEDOM OF VERTICAL MOVEMENT WITH RESPECT THERETO BETWEEN SAID TWO POSITIONS, INCLUDING HYDRAULIC POWER MEANS FOR ACTUATING SAID CLAMP BAR, SAID MEANS FOR APPLYING FLUID PRESSURE TO SAID PRESSER FEET COMPRISING A SOURCE OF AIR PRESSURE.

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