US3777339A

US3777339A - Apparatus for individually separating heddles and like objects from a row preparatory to a drawing-in operation

Info

Publication number: US3777339A
Application number: US00263573A
Authority: US
Inventors: S Fleischer; K Jeppsson
Original assignee: TITAN TEXTILE MACHINES
Current assignee: TITAN TEXTILE MACHINES
Priority date: 1971-06-17
Filing date: 1972-06-16
Publication date: 1973-12-11
Anticipated expiration: 1990-12-11
Also published as: CH550880A; DK127013B; DE2228690B2; DE2228690A1; JPS5122982B1

Abstract

Apparatus for individually and successively separating heddles from a row of heddles by means of an electromagnet which is moved towards the first heddle in a row to remove that heddle to a position in which a thread may be pulled through the heddle eyelet. During the first part of the movement of the magnet away from the heddle row, the magnet receives a relatively weak current ensuring that only one heddle is taken along, and when the heddle has been sufficiently detached from the remaining heddles in the row, the current is increased to increase the holding force of the magnet. Two or more heddles may be separated from different rows in one operation, preferably with a short time interval so that they will be moved to spaced drawing-in positions. The apparatus may also be used for separating drop blades and similar object preparatory to a drawing-in operation.

Description

United States Patent 1 Fleischer et a1.

[ APPARATUS FOR INDIVIDUALLY SEPARATING HEDDLES AND LIKE OBJECTS FROM A ROW PREPARATORY TO A DRAWING-IN OPERATION [75] Inventors: Svend Sigurd Christie Fleischer,

Klampenborg; Knud Helge Jeppsson, Copenhagen, both of Denmark [73] Assignee: Titan Textile Machines A/S,

Metalbuen, Ballerup, Denmark 22] Filed: June16, 1972 21 Appl, No.: 263,573

[30] Foreign Application Priority Data Dec. 11, 1973 Primary Examiner-James Kee Chi AttarneyFrancis C. Browne et a1.

[57] ABSTRACT Apparatus for individually and successively separating heddles from a row of heddles by means of an electromagnet which is moved towards the first heddle in a row to remove that heddle to a position in which a thread may be pulled through the heddle eyelet. During the first part of the movement of the magnet away from the heddle row, the magnet receives a relatively weak current ensuring that only one heddle is taken along, and when the heddle has been sufficiently detached from the remaining heddles in the row, the current is increased to increase the holding force of the magnet. Two or more heddles may be separated from different rows in one operation, preferably with a short time interval so that they will be moved to spaced drawing-in positions. The apparatus may also be used for separating drop blades and similar object preparatory to a drawing-in operation.

10 Claims, 5 Drawing Figures APPARATUS FOR INDIVIDUALLY SEPARATING IIEDDLES AND LIKE OBJECTS FROM A ROW PREPARATORY TO A DRAWING-IN OPERATION BACKGROUND OF THE INVENTION The present invention relates to an apparatus for individually separating heddles (or drop blades) from a row of heddles positioning a heddle for subsequent drawing-in of a warp thread from a warp through an eyelet of each heddle, which apparatus is provided with a gripper magnet that is movable towards and away from the row of heddles.

In a loom, the heddles are mounted in two or more weaving shafts and they serve to raise and/or lower the warp threads in accordance with the weave desired in the fabric whereby they form the so-called shed through which the weft thread is introduced. When reference is made in this specification .and the appended claims to heddles this word is to be construed as covering also the so-called stop motion or drop blades or warp detectors which, in a corresponding manner, are individually disposed the warp threads so as to render possible the stopping of the loom in the event of a warp thread. break.

It is known to utilize a permar'nent magnet mounted on a movable arm for separating a heddle (or drop blade) from a row of heddles and for advancing the heddle to a position spaced from the other heddles of th row for drawing-in a warp thread either'manually or mechanically. It has to be ensured that the retaining force of the magnet is no greater than is necessary for removing a'single heddle only from the row at a time, but this'entails a certain risk that during the movement of the magnet towards the drawing-in or heddling position the heddle is dropped for instance if the frictional or other resistance against the movement of the heddle along the supporting rails of the weaving shaft varies. The difficulties are increased further 'by the circumstance that heddles may have varying thickness and varying material properties or they may be more orless deformed in the area in which the magnet is to grip them. A magnet having a holding force suitable for separating relatively thick heddles may, for example, often be inclined to take two heddles at a time, when it is employed with thinner heddles. Consequently, it has in such cases been necessary to replace the magnets or, if possible, to change their holding force by adjusting the distance between their poles. Both these solutions are,

however, complicated and time-consuming.

BRIEF SUMMARY OF THE INVENTION According to the invention there is provided an apparatus for individually separating heddles and like objects, such as drop blades, from a row of heddles and positioning a heddle for subsequent drawing-in of a warp thread from a warp through an eyelet of each heddle, said apparatus comprising a gripper electromagnet, means for moving said gripper magnet towards and away from the row of heddles, and means for supplying said electromagnet with a relatively weak magnetizing current during the initial phase of its movement'away from the row of heddles, and with a relatively strong magnetizing current during the subsequent phase of said movement.

The invention has the advantage that the reliability of the apparatus is increased quite substantially by virtue of the fact that the separating operation is effected with It is'then possible to let the movement occur at a greater speed than according to the prior art since the retaining force can be increased to such a value that net can be safely transmitted to the heddle without any danger of the heddle being dropped from the magnet. The rate of operation of the apparatus can be stepped up in this way also because the strong magnetizing current can be switched on already after a very short travel of the heddle away from the row of heddles, in practice a few millimetres, as an air gap of this size effectively prevents magnetic attraction of the next heddle in the row.

The apparatus may comprise control means adapted to completely or substantially demagnetize the gripper magnet before it starts to move back towards the remaining heddles in the row. The heddle, through which a warp thread has been drawn, can then be readily pushed away from the heddling point because the magnet no longer exerts a holding force upon it. When the magnet is supplied with DC current, it is possible to I bring about the demagnetization by reversing the direction of the current through the magnet coil whereby any remanence in the gripper magnet and in the heddle is eliminated.

The control means may comprise a variable resistor for manual adjustment of at least the relatively weak magnetizing current. While it will be normally possible to operate with a fixed or constant high value of the strong magnetizing current, it is advantageous to be able, while the apparatus is in operation, to adjust the weak initial current, the optimum value of which depends to a larger extent upon the heddles employed.

The gripper magnet may be mounted on an arm supported in a reciprocating frame which is displaceable parallel to the row of heddles and which is provided with actuating means for a stationary change-over switch adapted to alternately couple the magnet coil to one or the other of two parallel feed or supply circuits for the electromagnet. It is achieved hereby that the change-over operation between the two different values of the magnetizing current always takes place at a specific point in the travel of the magnet.

The frame may be provided with a pawl means adapted to couple it to a reciprocating driving mechanism and to simultaneously close a switch forming part of both parallel supply circuits. The gripper magnet then receives current only during its movement so that, particularly in an apparatus having several magnets for separating heddles from a corresponding number of rows of heddles, the magnetization of the nonoperative, stationary magnets is avoided. Consequently, the non-operative magnets do not consume current'and' do not magnetize the associated heddles.

The driving mechanism of the frame may comprize an intermittently rotating drive shaft that carries a first cam adapted to close a switch common to both supply circuits, at least during the movement of the frame away from the row of heddles, and a second cam adapted to actuate a switch of a supply circuit for a magnet coil mounted in the frame and adapted to effect engagement of the pawl means with the driving mechanism. Hereby an exact synchronization between the movement of the gripper magnet and the switching on an off of the magnetizing current is achieved.

In an embodiment of the apparatus which has a plurality of frames and associated arms and gripper magnets for individually separating heddles from a corresponding number of parallel rows of heddles, the apparatus may be provided with a common driving mechanism for all the frames, the pawl means of each frame may be locked to the driving mechanism during the reciprocating movement of the mechanism, the second cam may be provided with two angularly spaced areas for successively actuating its associated switch, and the apparatus may be equipped with a programming device which connects the switch with the magnet coil of a selected frame and which, during the period between the two actuation operations of the switch, is advanced one step. It is then possible during each full revolution of the drive shaft which simultaneously acts as a control shaft to separate two heddles from their respective row of heddles and to move them unequally away from the respective row, following which two warp threads may be drawn in through their respective heddle eyelet either simultaneously by means of a double heddling hook, or successively with a single heddling hook. This possibility contributes further towards increasing the rate of operation that is attainable by the apparatus.

For effecting the demagnetization of the gripper magnet, as mentioned above, by altering the direction of the magnetizing current, the drive shaft may carry a third cam adapted to reverse the polarity of the supply circuit of the gripper magnet.

The drive shaft may carry a fourth cam designed in such a way as to, twice during a revolution of the shaft, actuate a change-over switch between two parallel supply circuits of an electromagnetic clutch which forms part of the shaft drive, of which circuits one connects the magnet coil of the clutch directly to a voltage source while the other comprises a manually actuable switch. Hereby an automatic control of the functions of the apparatus by a pulse switch' is made possible, which switch may, for example, be incorporated into the heddling hook.

Additional characteristic features and advantages of the invention will become apparent from the following description and the accompanying drawings which, in a rather diagrammatical form, illustrate the details of an embodiment of the apparatus which are deemed sufficient and necessary for understanding the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an end view of the apparatus mounted in connection with a plurality of weaving shafts and a warp beam, from which warp threads are to be drawn through the heddle eyelets of the shafts and provided with warp detectors or stop blades by means of the apparatus.

FIG. 2 shows an elevation of the heddles of a single weaving shaft with the associated gripping magnet and a part of its driving mechanism,

FIGS. 3 shows a view corresponding to FIG. 2, in which the driving mechanism has been omitted and where the gripper magnet has removed a heddle from the other heddles in the weaving shaft,

FIG. 4 shows a top plan view illustrating a part of the driving mechanism for the gripper magnets of the apparatus, and

FIG. 5 shows a wiring diagram for illustrating the function of the apparatus.

DETAILED DESCRIPTION The apparatus illustrated in the drawings has a carriage I which is supported by means of wheels 2 so as to be movable on rails 3 above and parallel to (i.e., at right angles to the plane of the drawing of FIG. 1) a plurality of weaving shafts 4 which, in a manner not shown in detail, aresupported in a frame of which the rails 3 form part.

Each weaving shaft is constructed as a frame, of which FIG. 1 shows the topmost and the

bottommost frame beam

5 and 6, respectively, and is provided with two horizontal supporting

rails

7 and 8 for the heddles 9.

The separating apparatus has, for each weaving shaft 4, a vertically downwardly projecting arm 10 that carries a gripper magnet 11 which is able to take a heddle 9 from the row of heddles supported by'the associated weaving shaft and to convey it forward to the heddling position, cf. FIGS. 2-3. The apparatus has, moreover, a plurality of arms 12, of which FIG. 1 shows only one, and each arm carries a gripper magnet 11 which, in a corresponding manner, is able to pull warp detectors or drop blades 13 forward from a series of drop blades and position a blade 13 in alignment with a heddle 9 which is separated with the aid of a magnet 11 on one of the arms 10. 7

Behind the frame (not shown) which carries the weaving shafts, the drop blades and the separating apparatus, a warp beam 14 with a warp 15 is supported in an appropriate manner. The threads of warp 15 are passed, from warp beam 14, across a guiding roll 16 and, in a known manner, held in a vertical position by means of a diagrammatically indicated thread clamp 17. An operator standing in front of the apparatus, that is to say to the right-hand side of FIG. 1, can, with the aid of a heddling hook, take the warp thread 18 of the warp, which at any time is located at the edge of the warp and pass it through the eyelet 19 of drop blade 13 and furtherthrough eyelet 20 of heddle 9 which assumes the heddling position. I

In timed relationship with the successive drawing-in of the individual warp threads the carriage l is moved by means of a drive motor (not shown) along rails 3, whereby it is ensured, inter alia, that the respective gripper magnets 11 are always in contact with the foremost heddle or drop blade of the associated row through which a warp thread has not yet been drawn in. Since the separation of heddles and drop blades takes place in principally the same, only the separation of heddles 9 is described in the following.

Each of the vertical arms 10 is supported in a separate frame 21 of carriage l. A driving rod 22 extends lengthwise through each frame 21-, the two end walls of which are provided with hearing bores (not shown) for the rod. All driving rods 22 are, at their left-hand end, as seen in FIGS. 2 and 4, coupled to a common cross bar 23 which, via two connecting rods 24, of which FIG. 4 only shows one, is coupled to cranks 25 provided on the extremities of a drive shaft 26 extending across and through carriage 1. Shaft 26 is supported in two bearings 27 rigidly connected with carriage l, and

cross bar 23 is guided in two guides 28 which may be shaped in such a way that at the beginning of its movement towards the left from the position shown in FIGS. 2 and 4, cross bar 23 is raised slightly, whereby frames 21 and carrying arms 20 are pivoted slightly in a clockwise direction (FIG. 2) which has the effect that a heddle 9 held by a retaining magnet 11 is raised slightly from its supporting

rails

7 and 8. Driving rods 22 which, behind frames 21, are supported in bearing bores of a cross bar 29 of carriage 1, must in that case have substantial play in the bearing bores.

Drive shaft 26 is driven by a motor 30 via an electromagnetic clutch 31 and a gear 32 which, in the embodiment shown, is made up of two gear wheels. For each revolution of shaft 26, cross bar 23 and frames 21 move once backwards and forwards in the longitudinal direction of the weaving shafts and, by means of the control circuit described below, one (or possibly two) of the arms is mechanically coupled to the associated driving rod 22 while the associated gripper magnet 11 is energized and, thereby, separates and removes a heddle 9 from the associated weaving shaft as shown in FIGS. 2 and 3.

Each driving rod 22 which, as mentioned, is ableto pass freely through the associated frame 21, is provided with two

recesses

33 and 34, and the frame has a pawl 35 secured to a spring arm 36 that is pivotable in the frame. Upon energization of a magnet 37, the spring arm 36 will be pulled downwards whereby pawl 35 is brought into engagement with one or the other of

recesses

33 and 34 dependent upon the moment of actuation of the magnet so that frame 21 with arm 10 and magnet 11 moves together with its driving rod 22. A mechanical locking mechanism (not shown) is provided which, subsequent to the arrangementof the pawl, maintains it in engagement with the driving rod until the rod has returned to approximately its startng position even if the current to electromagnet 37 is switched off.

The magnetizing coil (not shown) of the gripper magnet 11 is connnected between the frame of the apparatus and a wire 38'that extendsupwardlythrough the hollow arm 10 and is connected to a switch 39 mounted in frame 21, which switch is mechanically connected. to spring arm 36 so that the switch connects wire 38 to a wire 40 when pawl 35 is in engagement with one of the recesses of driving rod 22. Wire 40 is connected to a changeover switch 41 secured to carriage 1 so as to move therewith and which during movement of frame 21 relative to the carriage may be actuated by a roller 42 in engagement with an inclined surface 43 on the top side of the frame 21. Change-over switch 41 is in the position shown in FIG. 5 when frame 21 is in its rest position, but is changed over into its other positon when frame 21, by means of pawl 35, has been coupled to driving rod 22 and thus moves towards the left of FIG. 5. In the first-mentioned position, switch 41 connects wire 40 to wire 44, the other end of which is connected to the adjustable tapping or contact arm of a potentiometer 45, from which a line 46 establishes connection with a wire 47 which connects the second contact of change-over switch 41 to two interconnected contacts 48 and 49 of a gang or double changeover switch 50. From wire 47 a branch line 51 is connected to the above-mentioned magnet 37, the other power supply line 52 of which is connected to a movablecontact pin 53 which interacts with a punched tape 54. It will be seen from FIG. 5 that tape 54 has a longitudinal row of perforations 55 and an associated contact pin 53 for each gripper magnet 11 of the apparatus.

The change-over switch 50 mentioned above has

input terminals

56 and 57 connected to the plus and minus pole, respectively, of a voltage source for supplying DC current to the above-mentioned

magnets

11 and 37. Besides the two output terminals or contacts 48 and 49 referred to above, the change-over switch is fitted with a third contact 58 which, via a wire 59, is connected to a switch 60 that is actuated by a cam 61 mounted on drive shaft 26, as well as with a fourth contact 62 which, via a wire 63, is connected to a potentiometer 64 whose adjustable contact arm, via a wire 65, is connected to one of the two contacts of switch 60. Said contact is, via a wire 66, connected to the frame of the apparatus and to a switch 67 that is actuated by a cam 68 mounted on shaft 26. A line 69 leads from switch 67 to an electrically conductive drum 70, over which punched tape 54 is tracked in such a way that a contact pin'53, which extends through a perforation 55 in the tape, comes into conducting connection with drum 70.

A further cam 71 mounted on shaft 26 actuates the aforesaid double switch 50, and a cam 72 which also is secured to shaft 26, actuates a change-over switch 73 in the supply circuit for the coil of magnetic clutch 31. The coil is connected directly to one of the poles 74 of a voltage source, the other pole 75 of which is connected directly to one of the contacts of change-over switch 73 via a wire 76 and to the other contact of the change-over switch via a wire 77 that contains a manually actuated pulse switch 78. This switch may, for instance, be incorporated into the above-mentioned heddling hook or be a foot contact actuated by the operator.

The apparatus functions as detailed below.

In the rest position, FIGS. 2 and 3, in which cross bar 23 and all the frames 21 are in their right hand extreme position, shaft 26 and

cams

61, 68, 71 and 72 mounted thereupon assume the positions shown'in FIG. 5. The coil of magnetic clutch 31 is de-energized. one" of the contact'pins 53 associated with a retaining magnet 11 for one of the rows of heddles is, via aperfor'ation 55 in punched tape 54, in conducting contact with drum and the current circuit of the associated magnet 37 is therefore closed via contact 58, wire 59, switch 60, wire 66, switch 67,

lines

69, 52, 51 and 47 and contact 49. Thus, the associated pawl 35 is engaged in recess 33 of the associated driving rod 22 and switch 39 is closed. The coil of magnet 1 1 receives current via a circuit from contact 49 through wire 46, potentiometer 45,

lines

44, 40 and 38 to the frame which, via wire 66, switch 60 and wire 59 is connected with contact 58. In this case, the magnetizing current is relatively weak and its magnitude is dependent upon the position of the contact arm of potentiometer 45.

When the operator closes pulse contact 78, clutch 31 is energized and shaft 26 begins to rotate. After the shaft has turned a little, changeover switch 73 actuated by cam 72 switches in such a way that the clutch continues-to receive current via line 76 even if contact 78 is released. In response to the rotation of shaft 26, cross bar 23 and driving rods 22 are pushed forward, that is to say towards the left in FIGJ4, and that frame 21, selected by punched tape 54, whose gripper magnet 11 is energized, is moved forward along with the cross bar while the other frames 21 with associated arms 10 remain stationary in the position shown in FIG. 2. As briefly touched upon above, one of arms 12 is likewise moved forward so that its magnet 11 carries a drop blade 13 with it.

After an initial angular displacement of shaft 26 cam 68 breaks switch 67 whereby magnet 37 is deenergized, but since pawl 35, as mentioned above, is mechanically held in engagement with recess 33, the frame and gripping arm 10 continue their forward movment until clutch 31 is again disengaged when shaft 26 has rotated approximately 180, when change-over switch 73 changes to the position shown in FIG. 5. During this part of the revolution, switch 67 is closed once more by the second projection on cam 68 and if punched tape 54 has in the meantime been advanced one step, a magnetizing circuit for a magnet 37 associated with another frame 21 is established hereby so that pawl 35 of said other frame engages with the second recess 34 of the associated driving rod 22. The magnetizing circuit to the gripper magnet 11 of this other frame is also closed so that a heddle 9 of another weaving shaft isseparated and moved some distance forward away from the remaining heddles on that weaving shaft. This possibility appears from FIG. 3, in which there are shown in fully drawn and dotted lines, respectively, two

heddles

9 and 9 which have been moved unequal distances away from their respective rows of heddles, the first heddle being separated when a pawl 35 engages with a recess 34 while the heddle 9', shown with a dotted line, was separated when the associated pawl engaged with a recess 33.

After a very short travel of frame 21 and, hence, gripper magnet 11, roller 42 moves down the inclined surface 43 whereby change-over switch 41 connects the coil of the gripper magnet directly via wire 47 to contact 49 of change-over switch 50. Then the gripper magnet receives the fully magnetizing current and hence exerts an increased holding force as has been described in the foregoing.

When the operator has drawn a warp thread through each heddle 9 held by a magnet 11 (and, if necessary, also through a drop blade 13), he again actuates switch 78 whereby clutch 31 is engaged once more so that shaft 26 continues its rotation back into the starting position shown in FIG. 5. During this rotation, frame 21 with arm 10 first moves a short distance further towards the left before it reverses and approximately at the same time cam 61 breaks switch 60, so that the magnetizing circuit of retaining magnet 11 is interrupted. Shortly after this, cam 71 actuates the double change-over switch 50, whereby the magnetizing circuit is switched on again, this time, however, via wire 63 and potentiometer 64. As the direction of the current is reversed now, it is ensured that any remanence in magnet 11 will be eliminated. At the same time the operator may twist arm 10 (in a manner not shown in detail) slightly about its vertical axis, as has been indicated in FIG. 1 for one of arms 10, so that during the return movement, the arm and gripper magnet 11 are clear of heddle 9 which may be manually pushed further to the side towards the previously drawn-in heddles of the same wearing shaft. Before shaft 26 stops again in the position shown in FIG. 5, change-over switch 50 is again returned to its starting position so that the operating sequence can be repeated with the next heddle selected by the p'unched tape 54 which, in the intervening period, is moved one more step forward.

It will be understood from the above description that drive motor 30 may rotate constantly since an electromagnetic clutch has been inserted between the motor and shaft 26. It would be possible, however, to dispense with the clutch if a so-called stepping motor is used as drive motor. The two

potentiometers

45 and 64 are adjustable from the outside of the apparatus and can thus be adjusted during operation. In certain circumstances it will be possible to dispense with potentiometer 64 which regulates the value of the demagnetizing current. A similar potentiometer might be inserted into the common power supply line from the input terminals which supply the relatively strong magnetizing current to the magnets 11. If no need exists of separating two heddles (and drop blades) in the same operation, then cam 68 is replaced by a cam which is provided with one projection only for actuating switch 67. The stepwise movement of carriage 1 parallel to the weaving shafts referred to previously can be controlled by a sensor which bears against the edge of warp l5 and which provides a signal for starting the motor each time a certain number of warp threads have been drawn through heddles and/or drop blades. However, the carriage may also be moved by a pawl mechanism which advances it one step each time a warp thread is drawn in. Before the operation is initiated, the carriage is positioned so that each magnet 11 is in contact with the foremost heddle in the respective row of heddles. It is also possible to employ the apparatus when drawing in warp threads from more than one warp layer and in such a case punched tape 54 may be expediently provided with a corresponding number of perforation series with associated contact pins that provide current for lamps fitted at the respective warp layers so as to mark from which layer the'thread has to be taken.

The invention has been described in the foregoing in connection with an apparatus for separating heddles from several rows of heddles and with a gripper magnet and associated separate driving means for each row of heddles so tht only that gripper magnet, which simultaneously receives magnetizing current, moves away from the row of heddles. However, it will also be possible to couple all gripper magnets together mechanically in such a way that all move away from the respective row of heddles during each drawing-in operation since the selective energizing of the gripper magnets ensures that only heddles from the selected row or plurality of rows are transferred. The invention may also be utilized in connection with an apparatus that has only a single gripper magnet for operating upon several rows of heddles in which case the magnet will be moved transversally in through the apertures of the weaving shafts and, controlled by a programming device or by a patterning device, be caused to stop in register with the selected weaving shaft before it is supplied with magnetizing current to separate a heddle from the shaft in question. Subsequent to the termination of the separating operation, the magnet or magnets are again moved clear of the weaving shafts.

Instead of, as shown, being mounted on the ends of their respective arms 10, the gripper magnets could be fitted in another position along the arm which position may be adjustable. It would also be possible to have two spaced gripper magnets mounted on each arm, for example one at the top and one at the bottom of the associated row of heddles. The magnets may be detachably secured to their arms by means of a mechanical quick connector which at the same time provides the electrical connection between the magnet coil and the power supply line. Even if the apparatus is described and shown as being mounted above the weaving shafts, it could also be mounted below these, or there might be provided one apparatus above and one below the weaving shafts. That part of the frame in which the weaving shafts are supported which has not been described can, broadly speaking, be constructed as described in US. Pat. No. 3,653,106 which is herewith incorporated by reference.

The term weaving members as used in the following claims is to be construed as covering both the heddles and drop blades mentioned above.

We claim:

1. An apparatus for individually separating a weaving member having a passage for the drawing in of a warp thread from a row of such weaving members and for positioning the weaving member for said drawing-in of a warp thread from a warp through said passage of the weaving member, said apparatus comprising a gripper electromagnet means for moving said gripper electromagnet towards and away from said row of weaving members and means for supplying said electromagnet with a first current during an initial phase of the movement of the electromagnet away from said row of weaving members, and with a second magnetizing current during a subsequent phase of said movement, said first current being weaker than said second current.

2. An apparatus as claimed in claim 1, comprising separate control means for effecting at least substantial de-magnetization of said gripper electromagnet before its return movement towards the row of weaving members commences.

3. An apparatus as claimed in claim 2, in which said first and second magnetizing currents are DC currents, and said control means is adapted to reverse the direction of the current through the magnet coil to effect demagnetization.

4. An apparatus as claimed in claim 1, wherein said current supply means comprises a variable resistor for manually adjusting the value of at least said first magnetizing current.

5. An apparatus as claimed in claim 1, comprising a frame and drive means for reciprocating said frame parallel to the row of weaving members, means in said frame for supporting an arm on which said gripper electromagnet is mounted, said current supply means comprising two parallel feed lines and a stationary changeover switch adapted to selectively connect the coil of said gripper electromagnet to either of said feed lines and an actuating member mounted in said frame for actuating said change-over switch.

6. An apparatus as claimed in claim 5, comprising a pawl member mounted in said frame for releasably connecting said frame to its drive means and a switch connected in each of said parallel feed lines and adapted to be closed by said pawl member when the frame is being connected to its drive means.

7. An apparatus as claimed in claim 6, wherein said drive means for said frame comprises a drive shaft, drive means for intermittently rotating said drive shaft, first and second cams secured to said drive shaft, and said current supply means comprises a switch connected in each of said parallel feed lines and adapted to be closed by said first cam at least during the movement of said frame away from the row of weaving members, a magnet coil mounted in said frame for effecting engagement of said pawl member and a current feed line for said magnet coil including a switch actuated by said second cam.

8. An apparatus as claimed in claim 7, comprising a plurality of frames with associated arms and gripper magnets for separating weaving members from a corresponding number of parallel rows of weaving members, a common drive mechanism for the reciprocating movement of all the frames, means for locking said pawl member of each frame to said drive mechanism during reciprocation of that frame, said second cam having two angularly spaced regions for successively actuating the associated switch, the apparatus further comprising a programming device connecting said lastmentioned switch to the magnet coil of a frame selected by said programming device, and means for advancing said device one step during the period between two successive actuations of the switch.

9. An apparatus as claimed in claim 7, comprising a third cam secured to said drive shaft for reversing the polarity of the current through said gripper electromagnet.

10. An apparatus as claimed in claim 7, comprising a a fourth cam secured to said drive shaft, an electromagof said drive shaft.

Claims

5. An apparatus as claimed in claim 1, comprising a frame and drive means for reciprocating said frame parallel to the row of weaving members, means in said frame for supporting an arm on which said gripper electromagnet is mounted, said current supply means comprising two parallel feed lines and a stationary change-over switch adapted to selectively connect the coil of said gripper electromagnet to either of said feed lines and an actuating member mounted in said frame for actuating said change-over switch.

8. An apparatus as claimed in claim 7, comprising a plurality of frames with associated arms and gripper magnets for separating weaving members from a corresponding number of parallel rows of weaving members, a common drive mechanism for the reciprocating movement of all the frames, means for locking said pawl member of each frame to said drive mechanism during reciprocation of that frame, said second cam having two angularly spaced regions for successively actuating the associated switch, the apparatus further comprising a programming device connecting said last-mentioned switch to the magnet coil of a frame selected by said programming device, and means for advancing said device one step during the period between two successive actuations of the switch.

10. An apparatus as claimed in claim 7, comprising a fourth cam secured to said drive shaft, an electromagnet clutch in the drive means for said shaft, first and second parallel feed lines for said clutch, said first feed line connecting the magnet coil of the clutch directly to a voltage source said second feed line including a manually operable switch, a change-over switch for selectively connecting the coil of the clutch to either of said parallel feed lines, said fourth cam being shaped so as to actuate said switch twice during each revolution of said drive shaft.