US3171221A - Calenders for pressing laundry - Google Patents

Description

March 2, 1965 H. c. A. ZWAARD CALENDERS FOR PRESSING LAUNDRY Filed Jan. 17, 1963 INVENI OR 6'. A. ZWAARD BY KM HENDRICUS ATTORNEY:

United States Patent 3,171,221 CALENDERS FOR PRESSING LAUNDRY Hendricus C. A. Zwkaard, Prineesselaan 12, Rijswijk, South Holland, Netherlands Filed Jan. 17, 1963, Ser. No. 252,197 Claims priority, application Netherlands, Jan. 23, 1962, 273,838 3 Claims. (Cl. 38-55) The invention relates to a calender for pressing laundry with one or more rollers rotatably arranged in heated troughs, said rollers being supported in arms attached to the frame of the calender and adapted to execute a swinging movement, means being provided for swinging said arms to lift the rollers out of the troughs. During the working of the calender the rollers are to be held in the troughs with a certain pressure in order to obtain the required treatment of the laundry. In the case that no laundry is treated in the calender the rollers are to be lifted out of the troughs because otherwise the lining of the rollers would be scorched. Hitherto the lifting of the rollers was obtained in a mechanical way whereas also hydraulically operated means were used. These embodiments have the disadvantage that in a mechanical operating device the pressure of the rollers in the troughs cannot be controlled easily and in applying hydraulically operated means double-acting cylinders are used so that both the pressing and lifting is obtained hydraulically, and if there is some trouble in the hydraulic installation the rollers cannot be lifted out of the troughs and if they are already in their lifted position they fall back in the troughs. One has the same disadvantage when instead of a liquid an other fluid, for example air, is used.

The invention has for its object to provide a very simple lifting device in which it is easy to control the pressure of the rollers in the troughs and in which the above mentioned disadvantage has been eliminated. According to the invention said means for swinging said arms consist of at least one hinged cylinder and of at least one hinged pretensioned spring, both mounted between one of said arms and a fixed part of the calender, such that the cylinder is working in the direction for pressing the rollers in the troughs and the spring is biasing the arm in opposite direction. The advantage is here that a very simple cylinder can be used and that when the supply of electricity or of pressure air is interrupted the rollers are automatically lifted out of the troughs by said spring,

In a very effective embodiment of the calender according to the invention the center lines of said spring encloses such an angle with the corresponding arm that the distance between the hinge of said arm and the center line of said spring increases when said arm swings in the direction of the easing of said spring, such that the moment exerted by the force of said spring in relation to said hinge has a substantially constant value.

In such a device the said spring in the uppermost position of the roller has toexert such a force that the weight of the roller can be supported.

The tension in the spring will increase during the lowering of the roller and will be in fact inversely proportional to the length of said spring.

In the case that the spring would be arranged in such a way that said spring was directed perpendicularly to the arm being in its lowermost position, at a certain fixed value of the lifting height the increase in the spring pressure at the lowering of the roller would be so large that a cylinder with an extremely large diameter would be required to produce the necessary force with a certain pressure of the fluid.

It is possible to prevent the application of such a large cylinder by reducing the increase of the spring tension ice by means of an extremely long pressure. spring. Such a long pressure spring however is: very diflicult to accommodate. Owing to the described oblique position of said spring it is possible to have. such an arrangement that the moment exerted by the force of said spring has a substantially constant value so that the desired a ge lifting height in order to have a good accessability of the trough can be obtained, whereas a spring of normal length and a. cylinder with a small diameter can be used.

According to the invention the distance between the point of connection of said cylinder to said arm and the hinge of said arm can be adjusted. So it is possible. when applying a series of rollers to press, if required, one of the rollers with a greater pressure in the trough.

The invention will 'be elucidated in the following description of an embodiment of a calender in accordance with the invention.

In the single figure of the drawing is shown a diagrammatic elevation of a calender according to the invention with a number of rollers rotatably arranged in corresponding troughs, parts being shown in section. Only one trough with the corresponding roller is completely drawn and the invention will be descrribed in connection with this part of the calender. In a trough 2 mounted on a frame 1 a roller 3 is adapted to rotate. The roller 3 is supported in bearings 4 which are mounted in arms 5. The arms 5 are hinged on a shaft 6 mounted in the frame 1. A pneumatic cylinder 7 is hinged to the frame 1 at 8 whereas the free end of the piston rod 9 of the cylinder is hinged to the free end of the arm 5 at opening 10. The cylinder hinge point to the arm 5 may be adjusted by pivot ing the piston rod 9 in any one of the series of openings 10, 10a, 10b. In telescopically cooperating sleeves 11 and 12 a spring 13 is mounted, sleeve 11 being hinged to the frame 1 at 14, the sleeve 12 at the other end of the spring being hinged to the arm 5 at 15. If pressure air is supplied to the cylinder 7 through upper duct 16 the roller 3 is pressed in the trough 2 against the action of spring 13.

The sleeves 11 and 12 with the spring 13 are positioned obliquely in relation to the arm 5 so that the distance between the center of the shaft 6 and the center line 14-15 of the spring 13 increases when the arm 5 moves in the position 5a. The increase of the distance p to the distance pa is defined in such a way that the product of the force exercised by the spring 13 and the arm p of the couple remains substantially constant. So it is possible to allow with a rather small spring a rather large spring travel, so that in the position 3a the roller 3 is lifted sufficiently far out of the trough without the necessity that the pneumatic cylinder 7 has to exercise a too large force when pressing downwardly the roller 3.

What I claim is:

1. In a calender the combination of a frame, a fixed member on said frame, at least one arm pivoted to said frame about a hinge axis, a roller journaled in said arm for rolling against said fixed member, fluid pressure jack means pivotally connected to each of and between said arm and said frame, said fluid pressure jack means being so arranged that application of fluid pressure will move the :arm and roller toward said fixed member, a spring mounted in compression, means pivotally connecting one end of said spring to said arm and the other end to said frame, said spring urging the arm to lift the roller from said fixed member, and said spring having a center line disposed at such an angle with the arm that the distance between said hinge axis of the arm and the center line of said spring increases when said arm swings in the direction of the easing of said spring to maintain a substantially constant moment of force exerted by the spring as the arm moves said roller upwardly away from the fixed member.

2. In a calender the combination of a frame, a fixed member on said frame, at least one arm pivoted to said frame about a hinge axis, a rotatable roller journaled in said arm for rolling against said fixed member, a fluid pressure cylinder pivoted to said frame and including a piston and piston rod, said piston rod being pivotally connected to said arm, said fluid pressure cylinder being so arranged that application of fluid pressure to the cylinder will move the arm and roller toward said fixed member, a spring mounted between a pair of telescoping elements one pivoted to said arm and the other to said frame, said spring urging the arm to lift the roller from said fixed member, and said spring having a center line disposed at such an angle with the arm that the distance between said hinge axis of the arm and the center line of said spring increases when said arm swings in the direction of the easing of said spring, to maintain a substantially constant 4, moment of force exerted by the spring as the arm moves said roller upwardly away from the fixed member.

3. In a calender the combination according to claim 2 wherein means is provided for pivotally connecting said piston rod to said arm at different distances from said hinge axis.

References Cited by the Examiner UNITED STATES PATENTS 1,637,282 7/27 Schlatter 3852 1,936,027 11/33 Pointon 3857 X 2,138,397 11/38 Cannity 3852X 2,729,003 1/56 Cohu et al 3852 JORDAN FRANKLIN, Primary Examiner.

DAVID J. WILLIAMOWSKY, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,171,221 March 2, 1965 Hendricus C. A. Zwaard It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the grant, lines 1 and 12, and in the heading to the printed specification, line 3, name of inventor, for "Hendricus C. A. Zwkaard", each occurrence, read Hendricus C. A. Zwaard Signed and sealed this 27th day of July 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Altesting Officer Commissioner of Patents

Claims (1)

1. IN A CALENDER THE COMBINATION OF A FRAME, A FIXED MEMBER ON SAID FRAME, AT LEAST ONE ARM PIVOTED TO SAID FRAME ABOUT A HINGE AXIS, A ROLLER JOURNALED IN SAID ARM FOR ROLLING AGAINST SAID FIXED MEMBER, FLUID PRESSURE JACK MEANS PIVOTALLY CONNECTED TO EACH OF AND BETWEEN SAID ARM AND SAID FRAME, SAID FLUID PRESSURE JACK MEANS BEING SO ARRANGED THAT APPLICATION OF FLUID PRESSURE WILL MOVE THE ARM AND ROLLER TOWARD SAID FIXED MEMBER, A SPRING MOUNTED IN COMPRESSION, MEANS PIVOTALLY CONNECTING ONE END OF SAID SPRING TO SAID ARM AND THE OTHER END TO SAID FRAME, SAID SPRING URGING THE ARM TO LIFT THE ROLLER FROM SAID FIXED MEMBER, AND SAID SPRING HAVING A CENTER LINE DISPOSED AT SUCH AN ANGLE WITH THE ARM THAT THE DISTANCE BETWEEN SAID HINGE AXIS OF THE ARM AND THE CENTER LINE OF SAID SPRING INCREASES WHEN SAID ARM SWINGS IN THE DIRECTION OF THE EASING OF SAID SPRING TO MAINTAIN A SUBSTANTIALLY CONSTANT MOMENT OF FORCE EXERTED BY THE SPRING AS THE ARM MOVES SAID ROLLER UPWARDLY AWAY FROM THE FIXED MEMBER.

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