GB2055913A - Improvements in tufting machines - Google Patents

Abstract

A tufting machine includes a needle bar which can be moved endwise with respect to the fabric to be tufted by a pattern control mechanism and bar 27. The movements are imparted to the needle bar from slides 23, 24 which are reciprocated in opposite directions in a direction transverse to the fabric by cams 21, 22 and can be selectively coupled by latches 35, 36 to bar 27 connected to the needle bar under control of the pattern control mechanism to move the bar towards or away from the fabric while the needles are raised clear of the fabric. <IMAGE>

Description

SPECIFICATION Improvements in tufting machines In operation of a tufting machine the needle bar is reciprocated vertically, generally by means of push rods actuated by an overhead main drive shaft. It is known to produce a patterning effect in the tufted fabric by imparting endwise sliding movement to the needle bar with respect to the push rods by means of a cam, which operates to shift the needle bar while the needles are clear of the fabric. Each increment of sliding movement imparted to the needle bar is equal to, or a multiple of, the pitch of the needles to ensure that the needles will always be in register with the loopers which retain the loops of yarn projected through the fabric by the needles.

A similar effect can be achieved by a camoperated mechanism which periodically shifts the fabric laterally with respect to the needle bar, which in this case has no sliding movement with respect to the push rods.

The patterning which can be produced in this way is very limited, being determined by the shape of the cam, and to vary the pattern it is necessary to substitute another cam of different shape.

The object of the invention is to provide an improved cam-operated mechanism for shifting the needle bar or the fabric which will enable a wide variety of patterns to be produced in the tufted fabric under control of a pattern control mechanism.

The invention accordingly provides a tufting machine, comprising a main drive shaft, a needle bar, means for imparting vertical reciprocation to the needle bar from the main drive shaft to cause needles carried by the needle bar to project loops of yarn through the fabric to be tufted, a pair of slides which are constrained to move horizontally in a direction transverse to the fabric, a pair of cams which are driven from the main shaft and operate on the slides to reciprocate them in opposite directions, a bar extending parallel to the slides and movable to effect relative transverse movement between the needle bar and the fabric, latches which are selectively operable to connect the bar to one or other of the slides to impart incremental sliding movements to the bar in opposite directions while the needles are clear of the fabric, a further latch for restraining the bar from movement and a pattern control mechanism for selectively engaging the latches with one only of the latches engaged at any time in accordance with a predetermined programme, and said further latch engaged when neither of the other latches is engaged.

The bar may be connected to the needle bar, in which case the increments of movement imparted to the needle bar must of course be equal to or a multiple of the pitch of the needles, or to mechanism for imparting lateral movement to the fabric with respect to the needle bar, in which case the increments of movement need not be related to the pitch of the needles.

One embodiment of the invention is illustrated in the accompanying schematic drawings, in which: Fig. 1 is a sectional plan view, Fig. 2 is a section along the line Il-Il in Fig. 1, and Fig. 3 is a diagram showing a pneumatic system for controlling the machine.

The tufting machine illustrated includes a main drive shaft 10 carrying a number of eccentrics 11, one only of which is shown, which impart vertical reciprocating movement to a needle bar 12 in the conventional manner through the agency of push rods 13. The needle bar 12 extends transversely to the fabric 14 to be tufted, which is advanced continuously through the machine, and carries a multiplicity of equally spaced needles 15 which operate to project tufts of yarn through the fabric and cooperate in the conventional manner with loopers (not shown). The shaft 10 also drives a gear box 16, through chain and sprocket gearing constituted by sprockets 1 7, 18 and a chain 1 9.

The output shaft 20 of the gear box carries a pair of one step lift cams 21, 22 which are disposed at 1 800 to one another on the shaft 20 and impart reciprocation in opposite directions to slides 23 and 24, which are constrained to move horizontally in a direction transverse to the fabric to be tufted by guides 25 and carry followers 26 engaging the cams.

A pusher bar 27 is disposed between the slides 23, 24 and is supported by a cylindrical bearing 28 and a bearing 29 which engages a rectangular portion 30 of the bar and prevents it from rotating.

The bar 27 carries a block 31, opposite faces of which are engaged by rollers 32 on the needle bar 12, so that the needle bar can reciprocate vertically with respect to the bar 27 and endwise movement of the bar will impart sliding movement to the needle bar in a direction transverse to the fabric 14. A slot 33 in the needle bar enables it to slide with respect to the push rods 1 3.

Racks 34 are mounted on opposite faces of the rectangular portion 30 of the bar 27 having teeth at the same pitch as the lift of the cams 21, 22 and at the same pitch as the needles 1 5.

The slides 23 and 24 carry respective latches 35, 36 which are selectively engageable with the teeth of the racks 34 under control of solenoidcontrolled air cylinders 37 and 38.

The latch 35 is engaged to impart to the bar 27 incremental movements of one rack tooth pitch in the direction towards the fabric 14 from the slide 23 and the latch 36 is engaged to impart to the bar 27 similar incremental movements in the direction away from the fabric from the slide 24.

The latches 35, 36 are disengaged during the return movements of their respective slides.

A further latch 39 controlled by a solenoidcontrolled air cylinder 40 is engageable with one of the racks 34 to restrain the bar 27 against sliding movement.

As will be appreciated the bar 27 operates to impart sliding movement to the needle bar 12 while the needles 1 5 are raised clear of the fabric 14. The cams 21,22 make one revolution at each revolution of the shaft 1 0 and the timing of the lift of the cams in relation to the top dead centre position of the needle bar can be varied by adjusting the angular position of the sprocket 1 8 in relation to the shaft supporting it.

As shown in Fig. 3, the air cylinder 37 is controlled by a pair of solenoid-controlled valves V1, V2; the air cylinder 38 by a pair of solenoidcontrolled valves V3, V4 and the air cylinder 40 by a pair of solenoid-controlled valves V5, V6. All the valves are connected to an air line 41, connected to a source 42 of pressurized air and containing a filter 43 and a pressure regulating valve 44. The valves V1-V6 have associated solenoids S,S6.

The solenoids are selectively energized by electrical signals from a patterning mechanism 45 which are transmitted along lines L1, L2 and L3 in such manner that one only of the latches 35,36 and 39 is in operation at any time, the latch 35 is engaged only when the slide 23 is moving towards the fabric, the latch 36 is engaged only when the slide 24 is moving away from the fabric and the latch 39 is engaged whenever the other two latches are disengaged.

Fig. 3 shows the slide 23 moved by its cam 21 to its extreme right-hand position and the slide 24 moved by its cam 24 to its extreme left-hand position, the followers 26 being in contact with the high portions of their respective cams 21, 22 as shown in Fig. 2. The valve V5 is positioned to supply compressed air to the upper end of the cylinder 40 and the lower end of this cylinder is connected to exhaust by the valve V6 so that the latch 39 is engaged with the opposed rack 34. The valves V1, V2 and V3, V4 are positioned so that the cylinders 37 and 38 are caused to withdraw their latches 35, 36 from the opposed racks 34. The latch 39 remains engaged until the cams 21 and 22 have moved the slides 23, 24 to their alternative end positions and during this interval the needles 15 are moved down to make tufts and are raised clear of the fabric 14.If, during the return movement of the slides 23, 24 to the ppsition of Fig. 3, the pattern demands no change in the position in which the needles 1 5 engage the fabric 14, no signals are emitted by the mechanism 45 and the latch 39 remains engaged and the latches 35, 36 remain disengaged.

If, however, a shift of the needle bar 12 to the right is required by the pattern the mechanism 45 sends signals along the lines L1, L3to the solenoids 5i, S2 and S5, S5 to reverse the positions of the valves Vr, V2 and V5, V6 and so engage the latch 35 and disengage the latch 39. If a shift of the needle bar 12 to the left is required the mechanism sends signals along the lines L2, L3 to engage the latch 36 and disengage the latch 39.

The latch 39 is thus engaged when the slides 23 and 24 are stationary, during movement of the slides away from the position of Fig. 3 and also during return of the slides to the position of Fig. 3, when no sliding movement of the needle bar 12 is required. When, however, the pattern requires a shift in the position of the needle bar the mechanism 45 causes the latch 39 to be disengaged during the movement of the slides to the position of Fig. 3 and the appropriate one of the latches 35 and 36 to become engaged.

The system thus provides for a wide variety of the extent of sliding movement of the needle bar 1 2 in both directions, this being limited only by the number of teeth on the racks 34.

The patterning mechanism 45 can take many forms, e.g. punched or magnetic tape, a patterning chain of varying link height, a printed circuit card insert or a photo cell or fibre optics unit operating from an inked design on film through which light is passed.

Claims (6)

1. A tufting machine comprising a main drive shaft, a needle bar, means for imparting vertical reciprocation to the needle bar from the main drive shaft to cause needles carried by the needle bar to project loops of yarn through the fabric to be tufted, a pair of slides which are constrained to move horizontally in a direction transverse to the fabric, a pair of cams which are driven from the main shaft and operate on the slides to reciprocate them in opposite directions, a bar extending parallel to the slides and movable to effect relative transverse movement between the needle bar and the fabric, latches which are selectively operable to connect the bar to one or other of the slides to impart incremental sliding movements to the bar in opposite directions while the needles are clear of the fabric, a further latch for restraining the bar from movement and a pattern control mechanism for selectively engaging the latches with one only of the latches engaged at any time in accordance with a predetermined programme and said further latch engaged when neither of the other latches is engaged.

2. A tufting machine according to claim 1, wherein the bar is connected to the needle bar to impart sliding movement to the needle bar in a direction transverse to the fabric and wherein said increments of movement are equal to or a multiple of the pitch of the needles on the needle bar.

3. A tufting machine according to claim 2, which includes rack teeth on the bar which are engageable by said latches, said rack teeth being at the same pitch as the needles.

4. A tufting machine according to claim 1, which includes solenoids operable by the patterning control mechanism to effect selective engagement of the latches.

5. A tufting machine according to claim 4, which includes air cylinders for moving the latches into and out of engagement with the bar and valves controlled by the cylinders for supplying pressurized air to the cylinders to engage and disengage the latches.

6. A tufting machine according to claim 1, substantially as described herein with reference to the accompanying drawings.