HEALD CONTROL SYSTEM

Abstract: A heald control system including a statically mounted heald hook retention device and a reciprocating heald hook, the retention device being located adjacent to the reciprocatory path of travel of the heald hook, the device and heald hook having co-operating latch means which are relatively movable in a lateral direction relative to said path of travel of the heald hook for controlling engagement of the co-operating latch means to cause selective retention of the heald hook at a predetermined position along said path of travel, and selectively actuatable motive means for causing said relative movement between the co-operating latch means, said motive means including an elongate piezo-electric strip arranged to drivingly move one of said co-operating latch means, the piezo-electric strip being laterally deflectable relative to its length by application of an electric voltage to cause said relative movement between the co-operating latch means.

Description: HEALD CONTROL SYSTEM The present invention relates to a heald control system and to a loom pattern control apparatus including such a system. According to one aspect of the present invention there is provided a heald control system including a statically mounted heald hook retention device and a reciprocating heald hook, the retention device being located adjacent to the reciprocatory path of travel of the heald hook, the device and heald hook having co-operating latch means which are relatively movable in a lateral direction relative to said path of travel of the heald hook for controlling engagement of the co-operating latch means to cause selective retention of the heald hook at a predetermined position along said path of travel, and selectively actuaτable motive means for causing said relative movement between the co-operating latch means , said motive means including an elongate piezo-electric strip arranged to drivingly move one of said co-operating latch means, the piezo-electric strip being laterally deflectable relative to its length by application of an electric voltage to cause said relative movement between the co-operating latch means . According to one embodiment of the present invention a heald hook engagement member is provided which is movable along a path of travel between extended and retracted positions to cause retention of the heald hook, the path of travel of the hook engagement member intersecting the path of travel of the heald hook such that the heald hook engagement member moves across the path of travel cf the heald hook during its movement toward its extended position. The piezc electric strip is preferably arranged to have two positive positions of deflection, one for each Ξ polarity of applied voltage and these correspond to the extended and retracted positions cf the hook engagement membe . Alternatively one of these positions of deflection may correspond to an applied voltage whilst the other C corresponds to no applied voltage. The piezo electric strip may be directly connected to the heald hook engagement member so that displacement of the heald hook engagement member is the same as that undergone by the strip . Alternatively the strip may be indirectly connected to the heald hook engagement member so that displacement of the heald hock engagement member is the same as or different to that undergone by the strip. In one embodiment the latch means associated with the neald hook comprises a shoulder, for example defined by the wall of an opening, and the hook engagement member defines the co-operating latch means associated with the retention device. The heald hook may have a resiliently deflectable portion on which the latch means associated with the heald nook are located for co-operation with static latch means mounted to one side of the reciprocatory path of travel of the hook. With such an arrangement the heald hook engagement member is adapted to engage the heald hook in order to cause its deflection and thereby cause engagement between the co-operating latch means. Alternatively, the piezo-electric strip may be secured in face to face contact with the deflectable portion such that on activation of the piezo-electric strip lateral deflection of the strip causes a similar deflection of the deflectable portion. Alternatively, latch means may be movably mounted on the heald hook and the hook engagement member operates to cause deflection of the latch means on the hook -in order to -cause engagement with the static latch means. In one embodiment, two heald hook engagement members are provided, a first of said heald hook engagement members being operative to cause retention of the heald hook at one end of its path of reciprocal travel and a second of said heald hook engagement members being operative to cause retention of the heald hook at its opposite end of its path of reciprocal travel. Preferably the heald hook is biased in one direction of travel and is moved by a lifting knife in the opposite direction of travel, one of said heald hook engagement members being operative to cause engagement between the knife and the heald hook whilst the heald hook is located at one end of its path of travel. Each heald hook engagement member may be moved by a respective piezo electric strip or alternatively a single piezo electric strip may be provided for moving both heald hook engagement members . According to another aspect of the present invention there is provided a pattern control apparatus for a weaving loom including a heald control system as defined above. Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which:- Figure I is a schematic diagram of a piezo electric strip; Figure 2 is a schematic diagram of a heald retention device according to a first embodiment of the present invention within a pattern control apparatus; Figures 3 and 4 are diagrammatic representations of the embodiment cf Figure 2 illustrating operational modes of selection; Figures 5 and 6 are diagrammatic representations of a second embodiment illustrating operational modes of selection; Figure 7 is a schematic illustration of a third embodiment according to the present invention; Figure 8 is a schematic illustration of a fourth embodiment according to the present invention; Figures 9 and 10 are diagrammatic representations of a fifth embodiment illustrating operational modes of selection. Referring initially to Figure 1, there is shown a piezo electric strip 10 which comprises two layers of piezo electric material 10a_,lOJb. Electrical connections 11,12 and 13 are provided at one end of the strip 10 for the application of an electric voltage. The central connection 12 is common to both layers 10 _, 10b_. Application of a positive voltage to connections 11,13 and a negative voltage to connection 12 causes the strip to deflect laterally in one direction from a central non-deflected position _0 to a deflected position _l_ and application of a reverse voltage to connections 11,13 and 12 cause the strip to deflect laterally from position _0_ to a deflected position D2. A suitable piezo electric strip is manufactured by Morgan atroc and is referred to as a bi-morph strip. For such a strip, having a length of 100mm, a width of 8mm and thickness of 0.5mm, a deflection d of about 1.2mm (between position 0 . and Ol_ or D_2 . ) is achieved thereby providing a maximum displacement between positions JD1_ and D2 of 2.4mm. The applied voltage to achieve this deflection is 55 volts. The strip 10 remains in its deflected position Dl ,D2 as long as the appropriate voltage is applied to " connections 11,12 and 13. During application of the voltage, the strip acts as capacitor and becomes fully charged. Movement of the strip 10 to its non-deflected position _β_ is achieved by controlling the discharge of the strip. This may -be done relatively rapidly or slowly. In Figures- 2 to 4 the first embodiment of the present invention is illustrated in which healds (not shown) of a loom are raised and lowered. The method by which the healds are lifted is similar to that described in UK Patent No. 2047755. For example, as shown in Figure 2, healds (not shown) are attached to a lifting cord 1 which passes over a pulley wheel 2 to a fixing on the jacquard frame 3. Pulley 2 is attached to a second pulley wheel 3 via a housing 4 such that both wheels can rotate but are in fixed relationship to each other. A second cord 5 which passes round wheel 3 connects two heald hooks in the form of rods 6. These heald rods are raised and lowered alternately by knives 8 and S which press against knife hooks or abutments 100. The sequence of operation of the hooks is described in Patent cs UK 2047755 and European Patent 0119787 as are the knife drive means and the method of mounting and arranging the heald control devices . As illustrated in Figure 2, the upper portion 25 of each heald hook is reciprocated between an upper limit position L and a lower limit position L and a heald hook retention device 20 is located between each pair of connected heald hooks 5 in the region between positions U and L . The upper heald hook portions 25 are guided in a channel 26 formed by a spacer element 27 adjacent to each side of the retention device 20. In use, a plurality cf side by side retention devices 20 spaced apart by spacer elements 27 are provided across the width of the loom. The retention device 20 illustrated in Figures 2 to 4 includes a body 31 in which is housed a pair of piezo electric strips 10. One end of each strip 10 is fixedly mounted in a connection block 32 to which appropriate connections 11,12 and 13 are made. Each piezo electric strip 10 independently operates in the same manner to cause retention of an ad acent heald hook 6. For simplification of description retention of single heald hook 6 only will hereinafter be described. The upper portion 25 of the heald hook 6 is provided with an elongate aperture 34 and the retention device 20 is provided with a hook engagement member 36 in the form of a sheer pin 37. The pin 37 is axially movably mounted in a bore 38 formed in the body 31 for movement between extended and retracted positions. One end of the pin 37 is directly connected to the free terminal end of the strip 10 so as to be axially moved thereby so that when strip 10 is at positions _l_, _2_ the pin 37 is located at its fully extended and retracted positions respectively. The spacer element 27 is provided with a bore 28 which is in axial alignment with bore 38 such that on movement of the pin 37 from its fully retracted position (as seen in Figure 3) to its fully extended position (as seen in Figure 4) it enters into the bore 28. The pin 37 is moved from its retracted position to its extended position during movement of the aperture 34 passed bore 28. The length of the aperture 34 and the position of pin 37 relative to the reciprocal path of the hook 6 between positions UL and LL is chosen to permit sufficient time for the pin to enter the aperture 34 and reside in its fully extended position prior to the upper edge of the aperture engaging the pin 37. In the extended position of pin 37 it is received in both bores 28 and 38 on either side of channel 26. The pin 37 is therefore self-supporting in this position and does not transmit loadings onto the strip 10 which are imparted onto the pin 37 when supporting the hook 6. The strip 10 is therefore isolated from loadings which might otherwise cause damage. Isolation from loadings may be improved by adopting a loose connection between the strip 10 and pin 37. In order to release a hook 6 retained on a pin 37, the hook 5 is raised toward its UL position and in so doing lifts the upper edge of aperture 34 from the pin 37. The strip 10 is then deflected to position D_2_ by application of the appropriate voltage and thereby moves pin 37 to its fully retracted position. The hook 6 is then free to move to its lower position LL. Preferably the length of the aperture 34 is such that the lower edge of the aperture 34 is located below the pin 37 when the hook 6 is located at its upper position UL. In this way a maximum length of time can be provided for retracting the pin 37. Typically the width cf channel 26 is C .5mm and the thickness of the upper portions of hook 6 is 0.3mm. Since the maximum displacement between positions D_l_ and D_2 is utilised the stroke of movement of pin 37 is about 2.4mm. This enables a substantial length of pin 37 to be supported at either end in bores 28 and 38 to accommodate loadings applied by an engaged hook 6. In order to reduce inertia, the pin 37 is preferably made from a light weight material and is of small cross-sectional area, typically about 3mm diameter if circular. Preferably the upper edge of aperture 34 and the face of pin 37 which engages the upper edge are of complimentary profile so as to provide maximum contact surface. The material chosen for pin 37 is preferably a suitable hard wearing plastics or composite. A suitable plastics material is polyetheretherbetone. An alternative embodiment is illustrated in Figures 5 and 6 wherein the pin 37 is utilised as a means for deflecting the hook 6 rather than being used as a latch. In the embodiment of Figures 5 and 6 , instead of the < spacer element 27 being provided with a bore 28 it is provided with an inclined deflection surface 40 which is inclined at an acute angle 0 with the side wall 27a . of spacer element 27 defining channel 26. A static latch 42 formed on the spacer element 27 projects above surface 40 and is located at a position laterally offset from the path of travel of the hook 6 such that if undeflected the hook 6 does not engage latch 42. In this embodiment, since the static latch 42 is located on element 27, this element defines a retention device. To retain hook 6 on latch 42, the strip 10 is actuated, whilst the upper portion 25 of hook 6 is in its upper region of travel, to move pin 37 from its fully retracted position (as shown in Figure 5) to its fully extended position (as shown in Figure 6). In moving to its fully extended position, the pin 37 engages the upper portion 25 of hook 6 and causes it to bend about the transition edσe 44 between surface 40 and sidewall 27a. In deflecting upper portion 25 in this manner, the aperture 34 surrounds the latch 42 so that on downward movement of the hook 6 the upper edge cf aperture 34 engages latch 42 and thereby retains the hook 6 at an upper position. Preferably the upper portion of latch 42 which engages with the upper edge of aperture 34 is shaped to resist lateral separation between the hook and latch 42. This may be achieved as shown by the provision of an inclined support face 43. After retention of hook 6 on latch 42, the knife 8 descends and the hook 6 becomes suspended from the latch which thereby maintains engagement to restrain lateral separation. Thus after engagement of the upper edge of aperture 34 with latch 42 the pin 37 may be retracted to its fully retracted position. To release a retained hook 6, the pin 37 is retracted to its fully retracted position and the hook 6 is raised toward its upper position UL. Such movement raises the upper edge of aperture 34 away from latch 40 and enables the upper portion 25 to return under its inherent bias to an undeflected condition. The hook 6 is then free to move to its lower position LL without engaging latch 42. For the embodiment of Figures 5 and 6 at least the upper portion 25 of hook 6 is formed from a resilient material such as spring steel and is in the form of a thin strip. By changing the thickness of the strip and/or the position of the transition edge 44 below the pin 37 it is possible to change the force needed to be applied by pin 37 for bending the upper portion 25. In the embodiment of Figures 2 to 6 the pin 37 is directly connected to the piezo-electric strip 10 and as such the axial displacement of pin 37 is the same as that undergone by the strip 10. It is envisaged that the hook engagement member may be indirectly connected with the strip 10. This enables the strip to be isolated from loadings applied to the hook engagement member and also enables the displacement undergone by the hook engagement member to be different to that undergone by the strip. Thus for the embodiments of Figures 2 to 6 wherein the hook engagement member is pin 37, this enables the displacement stroke of the pin to be varied and also enables the applied force on pin 37 to be varied. An example of an indirect connection is illustrated in Figure 7 wherein the strip 10 is connected to the pin 37 via a lever 50 which is pivotally mounted on the body 31 via a pivotal connection " 52. Functioning of the pin 37 for ' causing retention of the hook 6 is the same as that described in the embodiment of Figures 2 to 4 , or Figures 5 and 6. The embodiment of Figure 7 further illustrates use of a single hook 6 for controlling movement of a heald (not shown) between its upper and lower shed positions. In the embodiment o.f Figure 7 the single hook 6 is connected to a heald to cause its movement between upper and lower shed positions in response to movement cf a single knife 55. In the embodiment illustrated the hook 6 is biased to toward its lower position LL and is retained in this position by virtue of a stop 56 mounted on the hook Ξ 6 engaging with a shoulder 57 on body 31. The hook 6 is provided with a laterally deflectable knife hook 60 which is biased to a retracted position. In the retracted position, the knife hook 60 is off-set from the path of travel of the knife 55 and so is not engaged by the knife 55. Accordingly whilst knife hook 50 is retracted the hook 6 remains at its lower position LL. A hook engagement pin 70 is provided which is axially slidably located in a bore 72 of the body 31 at a position facing the knife hook 60 when the hook 6 is at its lower position LL. The pin 70 is connected to one end of the strip 10 so as to be moved thereby between extended ana retracted positions . In order to raise hook 6, the strip 10 is deflected to position D_l_ which causes the pin 70 to be extended to engage knife hook 60 to move it to an extended position. In its extended position, the knife hook 60 projects into the path of travel of the knife 55 and is accordingly engaged thereby. Since pin 37 is also connected to strip 1G, on movement of pin 70 to its extended position, pin 37 is simultaneously moved to its retracted position in readiness for causing retention of the hook 6 at its upper position. This is achieved at the appropriate time by deflecting strip 10 to its position _2_ to move pin 37 to its extended position and cause retention of the hook 6 as described in the previous embodiments. The knife hook 60 is preferably in the form of a swinging latch which is biased under its own weight to its retracted position. Preferably the swing latch is arranged to engage a side face of body 31 or an appropriately positioned cam face for maintaining the knife hook 60 at its extended position whilst the hook 6 is retained at its upper position and the knife 55 has been lowered. An alternative arrangement to embodiment of Figure 7 is illustrated in Figure 8 wherein instead of using a single strip 10 to move pins 37 and 70 simultaneously, two strips 10c_,10d_ are provided for independently moving pins 37,70 respectively. Operation of the device shown in Figure 8 is otherwise the same as that for the device shown in Figure 7. It is envisaged that in the embodiments- of Figures 2 to 6, if desired, the upper end of strip 10 may be anchored to the connection block and the lower end of the strip 10 be connected to the hook engagement member. The position of the hook engagement member relative to the path of reciprocatory travel of the hook 6 would remain the same. Such an arrangement further isolates transmission of loadings onto the strip 10 from the hook engagement member. Furthermore it is possible to arrange the strips 10 of within one bodv 31 in a "head to toe" manner ie one strip with its lower end in a connection block and the other strip with its upper end in a connection block. In the embodiments described above, the fully extended and retracted positions of the hook engaging pins correspond to the displacement positions D1_,D2_ respectively of the strip 10. This means that the pins are positively held at their extended/retracted positions and this ensures reliability of operation. If desired position 0 may be adopted as one of the extended or retracted positions of the hook engaging pin. A fifth embodiment is illustrated in Figures 9 and 1C which operates in a similar manner to the embodiment of Figures 5 and 6, i.e. the latch means 34 is located on a deflectable portion 25 of the heald hook 5 and the portion 25 is deflected to bring about engagement of the latch means 34 with latch means 42. In the embodiment of Figures 9 and 10, the piezo- electric strip 10 is secured, for example by bonding, in face to face contact with the upper portion 25. Voltage is applied to the piezo-electric strip 10 by for example an electrical contact 80 which is slidingly contacted by the piezo-electric strip 10 as the hook 5 approaches its upper position UL. Preferably the hook 6 is formed of an electrically conductive material and is conveniently earthed. Accordingly a positive voltage may be applied via contact 80 to initially cause deflection of the piezo-electric strip 10 and corresponding deflection of upper portion 25 from the position shown in Figure 9 to that shown in Figure 10. Once the co-operating latch means 34,42 have been engaged, the piezo-electric strip may be discharged via contact 80. Thus on subsequent raising of hook 6 the upper portion 25 of hook 6 will return to its undeflected state (as shown in Figure 9 ) under its own bias . Alternatively it is envisaged that two contacts 80 may be provided for applying voltage of opposite polarity to -the piezo-electric strip. In this manner the piezo-electric strip can function to positively deflect the upper portion 25 for engagement of the co-operating latch means 34,42 (as shown in Figure 10) and to positively return the upper portion 25 to its undeflected position (as shown in Figure 9) by appropriately changing the polarity of the voltage applied via the two contacts . Due to the use of piezo electric strips 10 the power consumption is extremely low and no heating or electrical interference problems arise. This means that the devices can be compact and closely spaced. It is envisaged that the applied voltage for deflecting the strip 10 may be applied in a constant manner or by pulse. It will be appreciated that the upper wall of aperture 34 which forms the latch means 34 associated with the heald hook acts as a stop shoulder for location on the latch means associated with the retention device. It is envisaged that other constructions of shoulder may be formed on the hook in order to achieve the same function.

Claims: CLAIMS 1. A heald control system including a statically mounted heald hook retention device and a reciprocating heald hook, the retention device being located adjacent to the reciprocatory path of travel of the heald hook, the device and heald hook having co-operating latch means which are relatively movable in a lateral direction relative to said path of travel of the heald hook for controlling engagement of the co-operating latch means to cause selective retention of the heald hook at a predetermined position along said path of travel, and selectively actuatable motive means for causing said relative movement between the co-operating latch means, said motive means including an elongate piezo-electric strip arranged to drivingly move one of said co-operating latch means, the piezo-electric strip being laterally deflectable relative to its length by application of an electric voltage to cause said relative movement between the co-operating latch means . 2. A system according to claim 1, including a heald hook engagement member which ' is movable along a path of travel between extended and retracted positions to cause retention of the heald hook, the path of travel of the hook engagement member intersecting the path of travel of the heald hook such that the heald hook engagement member moves across the path of travel of the heald hook during its movement toward its extended position. 3. A system according to claim 2, wherein the piezo- electric strip has two positive positions of deflection corresponding to the extended and retracted positions of the hook engagement member. 4. A system according to claims 2 or 3, wherein the piezo-electric strip is directly connected to the heald hook engagement member so that displacement of the heald hook engagement member is the same as that undergone by the strip. 5. A system according to claims 2 or 3, wherein the piezo-electric strip is indirectly connected to the hook engagement member so that displacement of the hook engagement member is the same as or different to that undergone by the strip. 5. A system according to claims 4 or 5, including a body having a bore in which the hook engagement member is slidingly received, a spacer member being located adjacent to the body and spaced therefrom to define a channel in which the heald hook is reciprocally received, the spacer member having a recess opposed to the bore so that in its extended position the hook engagement member extends across the channel and is supported at opposite ends in said bore and said recess, said hook engagement member thereby defining the latch means associated with the retention device. 7. A system according to any of claims 2 to 5, wherein the heald hook has a resiliently deflectable portion having latch means for co-operation with static latch means mounted to one side of the reciprocatory path of travel of the hook, the heald hook engagement member being adapted to engage the heald hook in order to cause its deflection and thereby cause engagement between the co-operating latch means . 8. A system according to any of claims 2 to 5 wherein latch means are movably mounted on the heald hook and the heald hook engagement member operates to cause deflection of the latch means on the hook in order to cause engagement with static latch means mounted to one side of the reciprocatory path of travel of the hook. 9. A system according to claim 2, including two heald hook engagement members for each heald hook, a first of said heald hook engagement members being operative to control retention of the heald hook at one end of its path of reciprocal travel and a second of said heald hook engagement members being operative to control retention of the heald hook at its opposite end of its path of reciprocal travel . 10. A system according to claim 9, wherein the heald hook is biased in one direction of travel and is moved by a lifting knife in the opposite direction of travel, one of said heald hook engagement members being operative to cause engagement between the knife and the heald hook whilst the heald hook is located at one end of its path of travel . 11. A system according to claim 9 or 10, wherein the first and second hook engagement members are each connected to a respective piezo-electric strip. 12. A system according to claim 9 or 10, wherein a single piezo-electric strip is connected to both the first and second hook engagement members . 13. A system according to claim 1, wherein the heald hook includes a deflectable portion on which its associated latch means are located, the piezo-electric strip being 5 secured to the deflectable portion in face to face contact such that lateral deflection of the piezo-electric strip causes a corresponding lateral deflection of the deflectable portion of the heald hook. 14. A pattern control apparatus for a loom including a C heald control system according to any preceding claim.

Inventors: MAHBOUDIAN-JONES MALCOLM GAWAY, PARKES DAVID JOHN OWEN, MAHBOUDIAN-JONES, MALCOLM, GAWAYNE, BOUCHER, PARKES, DAVID, JOHN, OWEN
Applicants: BONAS MACHINE CO, BONAS MACHINE COMPANY LIMITED
Application year: 1992
Main classification: D03C3
IPC codes: D03C3, D03C13