GB2144778A - Tufting machine - Google Patents

Abstract

A needle bar 10 is reciprocated vertically (arrows 22) to produce tufts in a backing fabric 24. Each time the needle bar 10 is raised from the fabric 24, a controller 42 energises a reversible motor 30 to bring about longitudinal displacement of the needle bar 10 in accordance with a predetermined programme. The displacement mechanism includes a screw member 26 and a nut member 34, one of which is on the shaft 28 of the motor 30, the other non-rotatably connected to the needle bar 10. The speed of actuation of the motor 30 is synchronised with the speed of vertical reciprocation of the needle bar 10 since the interval of time for movement of a flag 46 attached to the reciprocating shaft 14 between proximity switches 47, 48 is computed for each vertical movement of the needle bar 10. If the needle bar is not going to complete its longitudinal movement in the available time the controller 42 stops the machine. <IMAGE>

Description

SPECIFICATION Tufting machine This invention concerns a tufting machine that is to say a machine of a kind comprising a plurality of needles, to which lifting yarn is fed, carried by a needle bar which is adapted to be reciprocated parallel to the axes of the needles for the latter to penetrate a backing fabric to introduce tufts into the latter.

The invention is more particularly concerned with a tufting machine as aforesaid in which the needle bar itself is controlledly displaceable in its longitudinal direction, that is to say transversely of the fabric and transversely to the direction of movement of the fabric past the needle bar, in order to produce a pattern, e.g. of zig zag, indented or like configuration.

Various proposals have already been made for effecting and controlling the patterning displacement of the needle bar, but in general these proposals have been complicated, and therefore relatively expensive and susceptible to breakdown.

An object of the present invention is to provide, in a turting machine as above discussed, an improved needle bar patterning displacement mechanism which is particularly simple in its construction and operation and is, therefore, economical to manufacture and reliable in use.

With this object in view the present invention provides a tufting machine comprising an elongate needle bar, a first mechanism for vertically reciprocating the needle bar so that the needles penetrate a fabric being worked upon, and a second mechanism for displacing the needle bar in its longitudinal direction to bring about tuft patterning of the fabric, characterised in thatthe second mechanism includes a screw member and a nut member the one member being connected to the needle bar and the other member being provided on the shaft of a reversible motor which is controlled by an electronic pattern controller to produce a predetermined pattern, and in that the first mechanism includes a rotatable member which moves in turn past two proximity switches connected to the pattern controller so that actuation of the needle bar longitudinal displacement mechanism is synchornised with the speed of vertical reciprocation and the vertical position of the needle bar.

Preferably the screw member is provided as an axial extension of the shaft of the motor and the nut member is a sleeve nut provided at one end of a non-rotatable drive bar the other end of which is connected to the needle bar.

Preferably the rotatable member of the first mechanism consists of a metal flag attached to a rotatable shaft which is displayed parallel to the needle bar and connected thereto by an eccentric and a connecting rod so as to bring about vertical reciprocation of the needle bar.

Advantageously the pattern controller is operative to monitor displacement of the needle bar in its longitudinal direction and to apply emergency brakes in the event that the necessary displacement is not accomplished rapidly enough relative to the speed of vertical reciprocation of the needle bar.

The invention will be described further, by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic diagram illustrating the needle bar reciprocation and patterning displacement mechanisms of a preferred embodiment of the tufting machine of the invention; and Figure2 is a schematic diagram illustrating how a rotatable member of the reciprocation mechanism passes two proximity switches connected to the patterning displacement mechanism.

The illustrated embodiment of the tufting machine of the invention comprises a needle bar 10 carrying a multitude of downwardly-projecting needles 12 each of which is fed, in known manner with a respective tufting yarn (not shown). A needle-bar reciprocating shaft 14 extends parallel to the needle bar 10, above the latter, and has thereon a plurality of eccentrics 16, one only of which is visible, with respective connecting rods 18 extending between such eccentrics 16 and the needle bar 10, and connecting with the latter so that the needle bar 10 is able to move in its longitudinal direction as indicated by the arrow 20 in the drawing.Naturally, rotation of the needle-bar reciprocating shaft 14will cause the needle bar 10to be reciprocated vertically as indicated by the arrow 22 to cause the needles 12 to p g nitrate a backing fabric 24 and produce tufts (not shown) therein.

A needle-bar patterning displacement mechanism of the machine comprises a screw member in the form of a course-pitch screw 26 which is provided as an extension of a shaft 28 of a reversible electric motor 30 and projects into a sleeve 32 one end of which is formed as a nut, as at 34, with which the screw 26 engages. The sleeve nut 32 is provided at one end of a coupling rod 36 the other end of which carries a plat 38 which interengages with spacedapart pair of cam followers 40 projecting from the needle bar 10 adjacent the end thereof.

The motor 30 is connected with a programmable stitch pattern controller 42 which in turn is connected with a synchroniser 44. A metal flag 46 attached to the needle bar reciprocating shaft 14 rotates in front of a pair of proximity switches 47,48 connected to the synchroniser 44, as indicated most clearly in Figure 2.

The method of operation of the illustrated arrangement will now be described. The needle bar 10 is reciprocated vertically as indicated by the arrows 22 to produce tufts in the backing fabric 24 in conventional manner. Each time the needle bar 10 is raised to withdraw the needles 12 from the fabric 24 (i.e. to the position shown) the controller 42 energises the motor 30 in accordance with the predetermined pattern programme to rotate the screw 26 in the one direction or the otherto shift the needle bar 10 correspondingly to acieve the desired tuft pattern.

The controller 42 is, of course, triggered by actuation of the proximity switches 47, 48. When the flog 46 actuates the first proximity switch 47 in the direction of rotation, this arms the controller 42 by indicating the shaft 14 has rotated past the so-called "top dead centre" position where the needles 12 are raised as far as possible from the fabric 24. Actuation of the second proximity switch 48 triggers the controller 42 to effect any necessary patterning step as mentioned above.

The time taken for the flag 46 to move between the first and second proximity switches 47, 48 is computed in the synchroniser 44. If this decreases, indicative of an increase in the speed of vertical reciprocation of the needle bar 10, the speed with which the controller 42 energises the motor 30 is increased by a corresponding amount so that longitudinal displacement of the needle bar 10 always occurs at the same stage in the vertical reciprocation cycle and the machine speed is not limited by the electronic signalling delays.

The controller 42 also constantly monitors the longitudinal displacement of the needle bar 10. If the needle bar 10 is not going to be able to move the correct distance in the programmed time, the controller 42 actuates a relay and thereby applies emergency brakes to the machine. This prevents excessive damage to components such as needles 12 and loopers which would occur if the needle bar 10 descended at an inappropriate longitudinal position. Such monitoring also pre-empts failure of the motor 30 or of electronic amplifying equipment and possible mechanical seizure.

Naturally, the invention is not confined to the precise details of the foregoing example, and variations may be made thereto. Thus, for instance, the sleeve nut 32, 34 may be provided directly on the shaft 28 and the screw 26 will then be provided on the coupling rod 36. The manner of connecting the latter to the needle bar 10 may, of course, differ from what is shown.

Claims (5)

1. Atufting machine comprising an elongate needle bar, a first mechanism for vertically reciprocating the needle bar so that the needles penetrate a fabric being worked upon, and a second mechanism for displacing the needle bar in its longitudinal direction to bring about tuft patterning of the fabric, characterised in that the second mechanism includes a screw member and a nut member, the one member being connected to the needle bar and the other member being provided on the shaft of a reversible motor which is controlled by an electronic pattern controller to produces a predetermined pattern, and in that the first mechanism includes a rotatable member which moves in turn pas two proximity switches connected to the pattern controller so that actuation of the needle bar longitudinal displacement mechanism is synchronised with the speed of vertical reciprocation and the vertical position ofthe needle bar.

2. Atufting machine as claimed in claim 1 wherein the screw member is provided as an axial extension of shaft of the motor and the nut member is a sleeve nut provided at one end of a non-rotatable drive bar the other end of which is connected to the needle bar.

3. A tufting machine as claimed in claim 1 or 2 the rotatable member of the first mechanism consists of a metal flag attached to a rotatable shaft which is disposed parallel to the needle bar and connected thereto by an eccentric and a connecting rod so as to bring about vertical reciprocation of the needle bar.

4. A tufting machine as claimed in claim 1,2, or 3, wherein the pattern controller is operative to monitor displacement of the needle bar in its longitudinal direction and to apply emergency brakes in the event that the necessary displacement is not accomplished rapidly enough relative to the speed of vertical reciprocation of the needle bar.

5. A tufting machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.