US3867966A

US3867966A - Electro-mechanical device for forming a shed in a weaving machine

Info

Publication number: US3867966A
Application number: US297697A
Authority: US
Inventors: Dietrich Wieland
Original assignee: Sulzer AG
Current assignee: Sulzer AG
Priority date: 1971-10-16
Filing date: 1972-10-16
Publication date: 1975-02-25
Anticipated expiration: 1992-02-25

Abstract

The heddles are displaced by means of an electro-static connection between a rotatable drum and electrically conductive cords or bands connected to the heddles and disposed about the drum. Electrical energization of the drum and selected cords causes an increase in frictional force between the drum and selected cords so as to cause movement of the cords with the drum and thus displacement of the heddles.

Description

es tat [191 ELECTRO-MECHANICAL DEVICE FOR FORMING A SHED IN A WEAVING MACHINE Inventor: Dietrich Wieland, Wendelstein,

Germany Assignee: Sulzer Brothers Ltd., Winterthur,

Switzerland Filed: Oct. 16, 1972 Appl. No.: 297,697

Foreign Application Priority Data Oct. 16, 1971 Germany 2151280 Nov. 13, 1971 Germany..... 2156534 Nov. 13, 1971 Germany..... 2156533 1.1.5. CI 139/55, 139/319 Int. Cl D03c 1.3/00, D03c 19/00 Field of Search 139/55, 57, 59, 78, 79,

References Cited UNITED STATES PATENTS 12/1854 Bonelli 1159/59 2/1911 Regal 139/319 Feb, 25, 1975 1,881,076 10/1932 Haebler 139/319 X 2,204,891 6/1940 Hamilton 139/55 3,499,473 3/1970 Pend et a1 3,817,292 6/1974 Doehler et a1. 139/55 FOREIGN PATENTS OR APPLICATIONS 523,037 4/1955 Italy 139/59 901,396 1/1954 Germany 139/319 1,122,745 8/1968 Great Britain 139/90 648,772 8/1928 France 139/319 364,239 5/1906 France 139/78 510,882 10/1930 Germany 139/319 Primary Examiner-James Kee Chi Attorney, Agent, or FirmKenyon & Kenyon Reilly Carr & Chapin 57 i ABSTRACT The heddles are displaced by means of an electrostatic connection between a rotatable drum and electrically conductive cords or bands connected to the heddles and disposed about the drum, Electrical energization of the drum and selected cords causes an increase in frictional force between the drum and selected cords so as to cause movement of the cords 'with the drum and thus displacement of the heddles.

7 Claims, 6 Drawing Figures 11 ELECTRU-MECHANICAL DEVICE FOR FORMING A SHED IN A WEAVING MACHINE This invention relates to an electro-mechanical device for forming a shed in a weaving plane.

In order to form a shed in a weaving machine, it is known to make use of wires or heddles having eyes through which warp threads are run. By raising or low ering certain heddles, some of the warp threads are separated from the others, so that a space is left between these two groups of threads, i.e., the shed. In simple weaving machines, these heddles are suspended in a certain sequence from shafts which raise or lower the corresponding warp threads, with all the heddles associated with one shaft raised or lowered by that shaft. In more complicated weaving machines, with which the number of warp threads to be moved independently of one another becomes very large, use is made of the so called Jacquard machine. In this case, instead of using shafts, hooked rods or lifting wires are used to which the associated warp threads are fastened by means of harness. The motion of these hooked rods is effected in accordance with whether or not they are, through the intermediary of a punched card and needle, pushed by means of a mechanically moved set of knives or blades.

With all the known devices (disregarding the Jacquard machine which for mechanical reasons nevertheless has a limited number of warp threads that can be moved independently of one another) it has been very difficult to reach high weaving speeds. This is because the masses to be moved at each change of shed, in acceleration or braking, are of considerable magnitude.

Accordingly, it is an object of the invention to reduce to a minimum the masses to be moved mechanically in a shed forming mechanism of a weaving machine.

It is another object of the invention to increase the number of warp threads to be moved independently of each other up to the total number of warp threads present.

Briefly, the invention provides an electro-mechanical device which connects to a plurality of heddles in a weaving machine so as to displace the heddles into predetermined positions for a shed. The device includes at least one rotatable drum, a plurality of electrically conductive harness cords which are disposed over the drum with each cord being connected to at least one heddle, and means for creating an electrically attractive force between selective cords and the drum for movement of the selected cords with the drum to displace the heddles connected thereto into the shed. In addition, each heddle is connected to a counteracting spring at an opposite end from a harness cord. The spring serves to maintain the heddle in a rest position and to return the heddle to this rest position after dis placement. Each heddle is also connected to a prestressing spring at the harness cord end. The prestressing spring serves to initially balance the heddle in the rest position by cooperating with the counteracting spring while also serving to reverse functions with the counteracting spring when the direction of drum rotation is reversed.

In operation, each heddle is fastened to a harness cord that is run, independently of all the others, over the rotating drum while the direction in which the drum rotates is preferably such that the heddle becomes lifted when there is sufficient friction between the drum and cord. The arrangement is such that the normal frictional force at the drum is unable to overcome the force of the counteracting spring at the other side of the heddle. When the heddle is to be lifted, the frictional force is increased by means of electro-static attracting forces, for example by means of the known Johnsen-Rahbek effect. The basis of this effect is that the friction between a bad conductor and a conductive element sliding thereon increases greatly as a result of electrostatic attraction, when an electric voltage is applied between the bad conductor and the conductive element. When an electric voltage is applied between the drum and the part of the: harness cord lying thereon, and made conductive, the friction between the drum and cord increases. This effects a lifting of the heddle against the force of the counteracting spring. When the electric voltage is switched off, the force of the counteracting spring again dominates, so that the heddle falls back to the rest or bottom position. With the direction of rotation reversed, a suitable alteration of the forces of the counteracting spring and the prestressing spring is made.

Of course, thearrangement may be suchthat the harness cords do not all run over the same drum, but are distributed among a number of similar drums. These drums advantageously have machined grooves to guide the harness cords.

The control of the individual harness cords is advantageously carried out by means of a suitable electronic device, which, depending on the degree of complexity of the fabric weave to be produced, has a plurality of outputs, whose number can be increased up to the number of warp threads present, e.g., as described in German patent application No. IP 21 52 434.5, filed Oct. 2, 1971.

It is also possible to control the individual'harness cords in chronological sequence, so that a so-called undulated shed is produced.

For simple weaves, it is indeed sufficient to work with relatively simple electric or electronic switches, whereby the harness cords are connected in parallel in suitable groups. For example, for the production of linen weave a simple switch, or an astable multivibrator, which switches over at each change of shed is sufficient. When only a simple weave is to be produced, it is also possible to groupthe harness cords of all heddles having the same lift together and to have the drum lift them in common. Instead of cords, it may also be advantageous to use bands which slide over the drum.

The drum can naturally be disposed above and/or below the weaving machine, whereby it is possible to arrange for high shed, low shed and upright shed.

In order to obtain sufficient attractive forces with relatively low voltages, use can also be made of electromagnetic attractive forces. To this end, the drum, for example, consists of ferromagnetic material, and the bands or harness cords are made of a flexible ferromagnetic material, for example of rubber filled with weak ly-magnetic ferrite, or of a similarly filled synthetic substance, and provided with a suitably disposed winding to produce the magnetic field.

A suitable means for retaining the displaced heddles in position in the shed can also be incorporated in the device so as to allow the electrostatic force creating means to be deactivated. For example, once displaced, each heddle can be retained by an electromagnet. This electromagnet would, in turn, be actuated in synchronism with the electrostatic force generating means and weaving machine so as to release the heddles when the shed is no longer required, e.g., upon completion of a weft insertion operation.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. ll schematically illustrates a device according to the invention;

FIG. 2 illustrates a device according to the invention with a number a rollers;

FIG. 3 illustrates a partial view of a drum having grooves according to the invention;

FIG. 4 illustrates a cross-sectional view through a band for lifting the heddles according to the invention;

FIG. 5 illustrates a plan view of the band of FIG. 4; and

FIG. 6 illustrates a modified construction according to the invention.

Referring to FIG. 1, the heddles l are suspended via insulators 2 at one end on conductive harness cords 3, and on the other end, on counteracting springs 4. The harness cords 3 run over a drum 5, made of a bad (i.e. poor) conductor type material, or coated with such a bad conductor type material, and are at their other ends, again through the intermediary of insulators 2, fastened to prestressing springs 6. An electric connection is made through a slide-contact 7 on the drum 5 and through connection wires 8 for the individual harness cords 3 in a suitable manner.

Referring to FIG. 2, instead of using a single drum, a plurality of drums 5 can be used with separate groups of harness cords 3 distributed among the drums 5.

Further, referring to FIG. 3, each drum 5 can be provided with annular grooves 9 each of which serves to guide a harness cord (not shown).

Referring to FIGS. 4 and 5, each harness cord 3 is made as a band of rectangular cross-section and of weakly magnetic rubber. The cord 3 is provided with a groove on one side together with an upraised portion so as to form pole surfaces 12 while allowing a winding I3 to be wound about the upraised portion within the groove. The winding 13 has a suitable current lead-in I4 and lead-out 14 at one end of the band 3 for connection to a suitable power source for generating a magnetic field via the winding 13.

Referring to FIG. 1, in operation, while the drum 5 is rotating, current is supplied to the drum 5 via the contact 7 while selected cords 3 are switched-in via the wires 8 to complete corresponding selected circuits. The selection of the wires 8 to be switched-in can be accomplished via a suitable electronic control such as that mentioned above. Thereafter, because of the creation of an electrostatic force between the selected cords 3 and the drum 5, these cords 3 are carried by the drum 5 in the direction of drum rotation against the force of the springs 4 until reaching a position, e.g., where the springs 4 balance the friction forces on the cords 3. The heddles I on these selected cords 3 are thus raised to the required points in the shed.

Upon switching-out of the wires 8 from the electrical circuit, as determined by the electronic control, the springs 4 bias the displaced cords 3 and heddles 1 back to the initial rest position as shown in FIG. II.

In order to form a low shed, the drum 5 is rotated in the opposite direction so as to carry the selected cords 3 and heddles I downwardly. The springs 4, 6 in this case reverse their respective functions.

Referring to FIG. 6, instead of maintaining the electrical connections through the shedding cycle of a weaving machine, a suitable restraining means can be used to hold the displaced heddles in place while elec trical contact is released. To this end, each band or harness cord 3 is run over a drum 5, rotating in the direction of the arrow, and is fastened at one side through the intermediary of an insulator 2 to a heddle l and at the other side to a counteracting spring or spring element 25. This spring 25 also serves to supply current from a connecting wire 26. The counteracting spring 25 is made as leaf-spring or wire-spring, and consists of ferromagnetic material, e.g., steel. The counteracting spring 25 is mounted so that during a heddle-lifting operation the spring 25 moves against an electromagnet 27 common to a number, or many, counteracting springs 25. This position is shown by the dotted line. The counteracting spring 25 of the raised heddles 1 re mains against the electromagnet 27 for as long as the electromagnet 27 is excited; while the counteracting springs 25 of the not-raised heddles do not become influenced by the electromagnet 27.

With electrostatic excitation(for example, as described above with respect to FIGS. 1 to 3), during a connection of the electromagnet 27 with the potential (i.e. pole) of the drum 5, vanishing(i.e. short circuiting) of the electrostatic attraction force, between the drum 5 and a cord 3 can be insured at the instant of application of the counteracting springs 25 against the electromagnet 27.

What is claimed is:

1. In combination with a plurality of heddles for forming a shed in a weaving machine; at least one rotatable drum, a plurality of electrically conductive harness cords disposed over said drum, each respective cord being connected to at least one respective heddle, [and] means for creating an electrically attractive force between selected cords of said harness cords and said drum for movement of said selected cords with said drum to displace said heddles connected thereto into a predetermined position, and means for retaining the displaced heddles in said predetermined position during deactivation of said means for creating an electrically attractive force.

2. The combination as set forth in claim I wherein each drum includes a plurality of annular grooves for guiding said respective harness cords therein.

3. The combination as set forth in claim 1 wherein at least some of said cords are in the form of bands and are connected to a plurality of heddles.

4. The combination as set forth in claim I wherein at least one cord is constructed of a weakly magnetic material having a winding therein for producing an electro-magnetic field.

5. The combination as set forth in claim 1, wherein said means for retaining the displaced heddles includes at least one electromagnet.

6. The combination of claim 1, wherein said means for retaining the displaced heddles includes a counteracting spring secured to a respective cord at one end and electrically connected at an opposite end to said means for creating an electrically attractive force to move into a preset position upon activation of said latter means; and an electromagnet electrically connected to said drum for retaining said spring in said preset position after deactivation of said latter means.

6 7. In combination with a plurality of heddles for drum for movement of said selected cords with said forming a shed in a weaving machine; drum during rotation of said drum to displace said at least one rotatable drum connected to one pole of heddles and Spring elements connected thereto a voltage source;

a plurality of electrically conductive harness cords 5 disposed over said drum, each respective cord being connected to at least one respective heddle;

a plurality of spring elements, each respective spring into predetermined positions; and

means for retaining the displaced heddles and spring elements in said respective positions, said means including an electrical connection with said one element being Connected to a respective one of pole for short circuiting the electro-static attracsaid cords to move therewith and to a second pole 10 force between 531d m Selected (ford of the voltage Source; upon movement ofa respective sprmg element into means for creating an electrically attractive force bethe respective predeterminedl position.

tween selected cords of said harness cords and said

Claims

1. In combination with a plurality of heddles for forming a shed in a weaving machine; at least one rotatable drum, a plurality of electrically conductive harness cords disposed over said drum, each respective cord being connected to at least one respective heddle, (and) means for creating an electrically attractive force between selected cords of said harness cords and said drum for movement of said selected cords with said drum to displace said heddles connected thereto into a predetermined position, and means for retaining the displaced heddles in said predetermined position during deactivation of said means for creating an electrically attractive force.

2. The combination as set forth in claim 1 wherein each drum includes a plurality of annular grooves for guiding said respective harness cords therein.

4. The combination as set forth in claim 1 wherein at least one cord is constructed of a weakly magnetic material having a winding therein for producing an electro-magnetic field.

7. In combination with a plurality of heddles for forming a shed in a weaving machine; at least one rotatable drum connected to one pole of a voltage source; a plurality of electrically conductive harness cords disposed over said drum, each respective cord being connected to at least one respective heddle; a plurality of spring elements, each respective spring element being connected to a respective one of said cords to move therewith and to a second pole of the voltage source; means for creating an electrically attractive force between selected cords of said harness cords and said drum for movement of said selected cords with said drum during rotation of said drum to displace said heddles and spring elements connected thereto into predetermined positions; and means for retaining the displaced heddles and spring elements in said respective positions, said means including an electrical connection with said one pole for short circuiting the electro-static attraction force between said drum and a selected cord upon movement of a respective spring element into the rEspective predetermined position.