GB1591613A

GB1591613A - Latch needles

Info

Publication number: GB1591613A
Application number: GB4454976A
Authority: GB
Original assignee: Grieve & Co Ltd T
Current assignee: Grieve & Co Ltd T
Priority date: 1977-10-20
Filing date: 1977-10-20
Publication date: 1981-06-24

Description

(54) LATCH NEEDLES (71) We, T. GRIEVE & COMPANY LIMI TED, à British Company, of Wolsey Road, Coalville, Leicester, LE6 4ES, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement According to the invention there is provided a latch needle having: (I) an elongate part with a hook, a stem and a slot in the stem, which slot is defined by flat sides extending from a front face to a rear face of the stem and being limited at the top end close to the hook and at a bottom end remote from the hook; and (II) a latch with a fin and a spoon, which latch is pivotably mounted in the slot for moving between a closed position with the spoon on the hook and an open position with the spoon on the front face of the stem, in which the slot extends at a right angle to the longitudinal stem direction directly from the front face to the rear face at the position where the spoon lies against the stem with the latch in the open position.

The slot may be arcuate at the top and bottom end and be formed by cutting with a circular saw. Conveniently the slot is limited at the bottom end by a pair of surfaces converging towards one another and towards the hook from the rear face and the front face of the stem. Thus the bottom end is formed by a substantially V-shaped overall surface which lies between the front face and the rear face.

Conveniently a latch pivot axis is located to extend through the slot in front of a stem portion defining the top end of the slot.

Suitably the slot converges at the top end towards the rear face of the stem in a direction away from the hook. Conveniently the slot converges substantially with the rear face.

Preferably the spoon includes a latch taper having surfaces diverging sideways from the fin and the slot extends directly from the front face to the rear face at a level where the latch taper lies with the latch in the open position. Advantageously the slot extends directly from the rear face to the front face at a level below the latch taper with the latch in the open position. The spoon accordingly may contact the stem at à position or area between the beginning and end of the latch taper. The actual position may vary from needle to needle provided a required latch stand results when the latch is in the open position. The range of possible contact positions for needles of a particular manufacture is referred to herein as an impact zone.Preferably the slot ceases to extend directly from the front face to the rear face at à level just below where the spoon lies against the stem in the open latch position.

Preferably an elongate aperture formed by the slot in the front face of the stem extends beyond the spoon when the latch is in the open position. The aperture conveniently ceases slightly beyond the latch e.g. by less than the length of the spoon. Suitably an elongate aperture, formed by the slot in the rear face of the stem has a length greater than the length of the fin and more than half of the length of the front face aperture. Preferably the lower limits formed by the apertures and the bottom slot wall are equidistant from the latch pivot axis whereas the upper limits of the apertures, formed at the junction of the top one wall and the front and rear face, are longitudirially off-set by a distance similar to or greater than the length of the fin.

Preferably the front facè has a chamfer for meeting the spoon. Suitably the chamfer is located to engage the spoon close to its widest cross-section. Alternatively the front face may have a struck notch for meeting the spoon. The notch may consist of a depressed part at the front face and parts; bulging into the through slots which comprise material which has been displaced in forming the depressed part.

The invention is particularly applicable to fine gauge needles of at least 18 gauge or finer. Conveniently sucho needles have watches with spoon widening out from- the fin at a latch taper by edged bevels. Suitably the stem portions on either side of the slot are raised to form a bulge of a lateral extent similar to that of the hook but greater than that of the stem below the slot. Advantageously the needles are adapted for high speed operation, for example by suitable curvature of the stem and shape of butts on the stem.

Preferably the fin is fitted without play in the slot.

The invention is more particularly described with reference to the drawings accompanying the Provisional Specification in which: Figure 1 shows a side view, partly in section, of a needle according to the invention in a closed position; Figure 2 shows a front view of the needle of Figure 1; Figure 3 shows a side view, from the opposite side as in Figure 1, of the needle of Figure 1 in the open position; and Figures 4, 5 and 6 show sections along lines X-X, Y-Y and Z-Z in Figure 3 respectively; and the drawings accompanying the Complete Specification in which: Figure 7 shows a partial side view partly in section of another needle according to the invention with the latch in a semi-open and open position: Figure 8 shows a front view of part of the needle of Figure 7; and Figure 9 shows a section along line A-A of Figure 8.

With reference to Figures 1 to 6, a needle is shown 20 times enlarged, and represents a 28 gauge needle. The needle comprises an elongate part 2 with a hook 4, a stem 6 and a slot 8. A pivot shaft 10 extends through the slot 8 and retains a latch 12 which has a fin 14 in the slot 8 and a spoon 16. Instead of providing a pivot shaft, a pivot may be formed by pushing stem material into a pivot aperture in the latch. The latch 12 is pivotable between the closed position of Figure 1 and the open position of Figure 3. The stem 6 has a front surface 18 with milled, generally concave chamfers 20 and a flat rear surface 22. The chamfers may also be formed by impressing a suitably shaped die on the front face of the stem 6.Figure 4 shows a section just prior to the beginning of a latch taper 24 of the spoon 16 having flat outwardly inclined surfaces 26; Figure 5 shows a section through the latch taper and Figure 6 shows a section just beyond the latch taper through the spoon 16. The spoon 16 meets the chamfers 20 in this case just beyond the latch taper. The outwardly inclined diverging surfaces 26 do not wedge into the slot 8 as a result of the provision of the chamfers 20.

The spoon 16 meets the chamfer 20 beyond the latch taper without any wedging. The manner in which the spoon meets the stem may vary from needle to needle even where they are manufacture in a batch. The needles are very small the shapes of the spoon and the stem are complex. Manufacturing variations within the required tolerances may cause the impact point of the spoon and the stem to shift longitudinally of the needles. The same may happen as a result of wear. In practice needles of a particular manufacture thus have an impact zone and the spoons contact the stems somewhere within the impact zone.

The manufacture is merely controlled so as to give a required latch stand for each individual needle. The latch stand is the transverse distance between the tip of the spoon in the open position and the rear face of the stem.

The slot 8 extends laterally between a front aperture 28 and a rear aperture 30. The slot 8 has atop wall 32 extending between an upper limit 34 at the front surface 18 and an upper limit 36 at the rear surface 22. The slot 8 has a bottom wall 38 spaced longitudinally from the top wall 32 and extending between lower limit 40 at the front surface 18 and a lower limit 42 at the rear surface 22. The bottom wall 38 includes two converging wall portions. The slot 8 extends laterally to interrupt the rear surface 22 well beyond the extremity of the spoon 16 in the open position. The slot 8 extends at right angles directly through the stem over a longitudinal extent 29 which is substantially equal to the length of the fin 14. The part of the slot 8 having the longitudinal extent 29 is referred to herein as a throughway.The throughway is defined on either side by parts of the stem 6 which have no direct physical connection.

The throughway commences below the pivot shaft 10, extends laterally through the stem 6 to the position (substantially at the section Z-Z) where the spoon 16 meets the stem 6, and ends above the tip of the spoon 16 when the latch is in the open position. The slot 8 can be formed by pushing circular saws into the front and rear surface of the stem 6.

The needles can be used on high speed knitting machine to reduce the incidence of needle damage and the need for needle replacement. Particular forms of damage whose incidence may be reduced are: I Chipping. This is caused by the latch flying open as the needle rises and the old yarn engages the fin near the latch pivot. The spoon then meets the stem with great impact, which can lead to metal of the stem being chipped away by the latch.

2 Surface deformation. This is caused by the latch and stem meeting and cutting into each other after prolonged use. This can lead to snagging of the yarn. Surface deformation may take place on the latch. The needle has a latch which is held tightly in the slot against transverse movement, yet pivots freely. Fluff/ and lint may pass efficiently through the rear aperture.

The average useful life of the needles may thus be increased in spite of the increased longitudinal extent of the slot 8 and the removal of metal from the zone of the needle subjected to spoon impact. Care should be taken not to extend the throughway too far downwards especially with fine gauge needles since this may make the stems prone to bending.

With reference to Figures 7 to 9, another needle is similar in all respects as the needles previously described, except that a notch 50 is struck by impressing a die at a point just above, the top of the bottom wall 38. The latch spoon 16 seats on the notch 50 in the open needle position.

WHAT WE CLAIM IS 1. A latch needle having: (I) an elongate part with a hook, a stem and a slot in the stem, which slot is defined by flat sides extending from a front face to a rear face of the stem and being limited at the top end close to the hook and at the bottom end remote from the hook; and (II) a latch with a fin and a spoon, which latch is pivotably mounted in the slot for moving between a closed position with the spoon on the hook and an open position with the spoon on the front face of the stem, in which the slot extends at a right angle to the longitudinal stem direction directly from the front face to the rear face at the position where the spoon lies against the stem with the latch in the open position.

2. A needle according to Claim 1 in which the slot is arcuate at the top and bottom end and is formed by cutting with a circular saw.

3. A needle according to claim 1 or Claim 2 in which the slot is limited at the bottom end by a pair of surfaces converging towards one another and towards the hook from the rear face and the front face of the stem.

4. A needle according to any of the preceding Claims in which a latch pivot axis is located to extend through the slot in front of a stem portion defining the top end of the slot.

5. A needle according to any of the preceding Claims in which the slot converges at the top end towards the rear face of the stem in a direction away from the hook.

6. A needle according to Claim 5 in which the slot converges substantially with the rear face.

7. A needle according to any of the preceding Claims in which the spoon includes a latch taper having surfaces diverging sideways from the fin and the slot extends directly from the front face to the rear face at a level where the latch taper lies with the latch in the open position.

8. A needle according to Claim 7 in which the slot extends directly from the front face to the rear face at a level below the latch taper with the latch in the open position.

9. A needle according to claim 7 or 8 in which the the slot ceases to extend directly from the front face to the rear face at a level just below where the spoon lies against the stem in the open latch position.

10. A needle according to any of the preceding Claims in which an elongate aperture formed by the slot in the front face of the stem extends beyond the spoon when the latch is in the open position.

11. A needle according to any of the preceding Claims in which an elongate aperture, formed by the slot in the rear face of the stem has a length greater than the length of the fin and more than half of the length of the front face aperture.

12. A needle according to Claim 10 and Claim 11 in which the lower limits formed by the apertures and the bottom slot wall are equidistant from the latch pivot axis whereas the upper limits of the apertures, formed at the junction of the top one wall and the front and rear face, are longitudinally off-set by a distance similar to or greater to or greater than the length of the fin.

13. A needle according to any of the preceding Claims in which the front face has a chamfer for meeting the spoon.

14. A latch needle substantially as described with reference to and as shown in Figures 1 to 6.

15. A latch needle as described with reference and as shown in Figures 7 to 9.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. longitudinal extent of the slot 8 and the removal of metal from the zone of the needle subjected to spoon impact. Care should be taken not to extend the throughway too far downwards especially with fine gauge needles since this may make the stems prone to bending. With reference to Figures 7 to 9, another needle is similar in all respects as the needles previously described, except that a notch 50 is struck by impressing a die at a point just above, the top of the bottom wall 38. The latch spoon 16 seats on the notch 50 in the open needle position. WHAT WE CLAIM IS

1. A latch needle having: (I) an elongate part with a hook, a stem and a slot in the stem, which slot is defined by flat sides extending from a front face to a rear face of the stem and being limited at the top end close to the hook and at the bottom end remote from the hook; and (II) a latch with a fin and a spoon, which latch is pivotably mounted in the slot for moving between a closed position with the spoon on the hook and an open position with the spoon on the front face of the stem, in which the slot extends at a right angle to the longitudinal stem direction directly from the front face to the rear face at the position where the spoon lies against the stem with the latch in the open position.

15. A latch needle as described with reference and as shown in Figures 7 to 9.