HEALD CONTROL APPARATUS

Abstract: A retention device for a heald rod which is reciprocated in a linear path, the retention device including an arm having at one end a latch formation for co-operating with said rod and being hinged to a support so that the latch formation is movable between a latch position and a non-latch position, an electromagnet having at least one pole positioned adjacent to the arm to be co-operable with a pole piece mounted on the arm and biasing means for biasing the arm so as to be normally spaced from said pole.

Description: HEALD CONTROL APPARATUS The present invention relates to a heald control apparatus which is particularly, but not exclusively, suitable for the heald control on a narrow fabric weaving loom. In our published U.K. patent application Mo. 2047755 we disclose heald control means and the present invention is particularly concerned with an improved construction of con trol means whereby higher speeds of operation may be attained. According to the present invention there is provided a retention device for a heald rod which is reciprocated in a linear path, the retention device including an arm having at one end a latch formation for co-operating with said rod and being hinged to a support so that the latch formation is movable between a latch position and a non-latch position, an electromagnet having at least one pole positioned adjacent to the arm to be co-operable with a pole piece mounted on the arm and biasing means for biasing the arm so as to be normally spaced from said pole. Various aspects of the present invention are here in after described with reference to the accompanying drawings, in which: Figure 1 is a side view showing several side by side heald rod retention devices; Figure 2 is a perspective view of one of the retention devices shown in Figure 1; and Figure 3 is a schematic illustration of the mechanism for operating the heald operating knives. The operation of the loom of the type to which the present invention particularly relates is described in our published U.K. patent application No. 2047755 and reference should be made thereto. Each weald eye (not shown) is controlled by a pair of heald rods 14 in a similar manner to that shown in Figure 1 of U.K. patent application No. 2047755 and each rod 14 is provided near its terminal end with an aperture 38 for selective engagement with a retention device 20. h plurality of retention devices 20 are provided arranged in closely spaced rows, there being one retention device 20 for each pair of heald rods 14. The retention devices 20 are conveniently mounted on a common board (not shown) extending across the loom. Each retention device 40 includes an electromagnet 22 which is removably mounted on a support block 23 which is secured to the board. At the upper end of the electromagnet 22 as shown in Figures 1 and 2 an angled bracket 25 is provided, one arm 25a of which is secured to the electromagnet and the other arm 25b of which seats upon the block 23 and is located on a projection 26. A similar projection 27 is provided on the support block 23 and a retaining plate (not shown) is located on projections 26 and 27 and retained in position by the bolt (not shown) passing through bore 24 in the support 23. Accordingly in the event of the electromagnet 22 failing it is a simple matter to replace it without disturbing the location of the remainder of the retention device. Conveniently the bracket 25 and support block 23 are plastics moulding. Secured on eitner side of the support block 23 and extending downwardly therefrom is a pair of retention arms 40 which co-operate with the heald rods 14 to selectively retain then in their raised position. Each retention arm 40 includes two components, namely a resilient member 41 and a rigid member 42 which are secured to one another for instance by riveting or welding. The arms 40 may be considered to comprise three distinct portions, viz, an upper portion 43, an intermediate portion 44 and a lower portion 45. The upper portion 43 is composed entirely of the resilient component and provides a hinge connection between the arm and the support block and provides the arm 40 with a resilient bias so that the arm 40 is normally spaced from the lower pole 46 of the electromagnet. Varying the length of portion 43 varies the amount of bias. Conveniently component 41 is a ribbon of spring steel. The intermediate portion 44 comprises both components 41 and 42 which are rigidly connected to one another. Component 42 is preferably composed of a material which can be easily magnetised, such as soft iron, and basically acts as a pole piece for co-operation with the lower pole 46, preferably the portion 44 is arranged so that its upper end is in contact with the upper pole 47 of the electromagnet. Accordingly the intermediate portion serves to rigidify the arm below the upper portion and also provides a magnetic path so that the portion of component 42 adjacent the lower pole will be a magnetic pole thereby creating a strong attractive force due to polar attraction. Accordingly, the response time for deflection of arms 40 on energisation of the electromagnet 22 is very quick. It is envisaged however that the portion 44 may be located in the region of the lower pole 46 alone. The lower portion 45 of each arm 40 serves to cooperate with the heald rods 14 for selective retention thereof. The lower portion 45 includes a window 50 formed in component 41 and through which projects a hook formation 51 formed at the terminal end of component 42. The hook formation 51 on penetrating the aperture 38 formed in the c6-operating rod 14 engages the upper edge of aperture 38 and thereby supports the rod 14. It is desirable that the hook formation 51 is resistive to impacts caused by rapid downward movement of the rods 14 and so the hook formation is constructed so as to be resistive to such impacts. In the preferred embodiment illustrated the terminal end of each component 42 is case hardened so as to provide a hook formation 51 which is resistive to such impacts. The component 41 projects downwardly beyond the hook formation 51 and defines a guide surface 53 for guiding the terminal end of rod 14 over the hook formation 51 during upward movement of the rod 14. In Figure 3 the mechanism for lifting the heald knives 60 is illustrated generally at 61 and includes a pair of arms 62 pivotally connected at 63 and whlch are caused to rise and fall relative to one another by a drive mecnanism 64. Two pairs of arms 62 are provided with the knives 60 extending therebetween. The drive mechanism 64 for each arm 62 includes a pair of cams 66 mounted on a drive shaft, one cam serving to positively raise the arm and the other cam serving to positively lower the arm. Each arm is therefore provided with a pair of cam followers 67, cam follower 67a serving to positively raise the arm and cam follower 67b serving to positively lower the arm. The shape of cams 66 are chosen so that when each arm 62 is in its raised position (which means that the rods 14 operated thereby have been lifted so that their terminal end is above the co-operating arm 40 of the retention device) there is an extended dwell time before lowering of the arm. This dwell time is advantageous in that it extends the period in which the retention device needs to -operate to deflect its associated arms 40. Accordingly, since the response time for deflecting the arms 40 is quick due to the construction of the retention device and since there is a dwell time for enabling such response to take place it is possible for the loom to operate at high speeds whilst ensuring positive and reliable operation of retaining selected heald rods 14.

Claims: CLAIMS 1. A retention device for a heald rod which is reciprocated in a linear path, the retention device including an arm having at one end a latch formation for co-operating with said rod and being hinged to a support so that the latch formation is movable between a latch position and a non-latch position, an electromagnet having at least one pole positioned adjacent to the arm to be co-operable with a pole piece mounted on the arm and biasing means for biasing the arm so as to be normally spaced from said pole. 2. A retention device according to Claim 1 wherein the electromagnet has a first pole located near to the said latch formation and a second pole located adjacent the arm but further from said latch formation, the pole piece extending along the arm so as to be magnetically co-operable with both poles. 3. A retention device according to Claim 1 or 2 wherein the pole piece has an extended portion which forms a hook so as to define said latch formation. 4. A retention device according to Claim 1, 2 or 3 wherein the arm is attached to the support by a resilient portion which defines the hinge connection and said biasing means. 5. A retention device according to any preceding claim wherein the arm comprises a resilient member connected to the support and a rigid elongate member fixedly secured to the resilient member, the rigid elongate member defining said pole piece and latch formation. 6. A retention device according to any preceding claim wherein a pair of arms are provided connected to a common support, the electromagent being positioned between the arms and being detachably mounted on said common support.

Inventors: GRIFFITH, JOHN DALTON BONAS MACHINE COMPANY LTD.
Applicants: TEXTILMA AG
Application year: 1983
Main classification: D03C3
IPC codes: D03C3