GB1582070A

GB1582070A - Securing needles to needle plates

Info

Publication number: GB1582070A
Application number: GB51402/77A
Authority: GB
Original assignee: DREI S PRAEZIS
Current assignee: DREI S PRAEZIS
Priority date: 1976-12-11
Filing date: 1977-12-09
Publication date: 1980-12-31
Also published as: DE2656246C2; DE2656246B1; CH625278A5; FR2373619A1; FR2373619B1

Abstract

In order to fix a flexible needle strip (1) in the groove (12) of a needle bar (7) by means of a hardening adhesive, there is provided a holding batten (13) which can be connected releaseably to the needle bar and which keeps the flexible needle strip aligned in a desired position during the hardening of the adhesive. Retention is obtained by means of a magnetic strip (25) which is provided on the holding batten (13) and which forms one side face of the holding batten. As a result of the magnetic design of this side face, the needles of the needle strip are held, at least over part of their shank length, without the risk of damage to the especially sensitive needle tips. <IMAGE>

Description

(54) SECURING NEEDLES TO NEEDLE PLATES (71) We, DREI-S-WERK PRAZISION SWERKZEUGE GmbH a German Body Corporate, of Nordliche Ringstrasse 14, D-8540 Schwabach, West Germany, 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:- The invention relates to a retaining plate for use in securing needles in needle plates, the combination of such a plate with a needle plate, and a method of securing needles in a needle plate.

Needles for insertion in needle plates are supplied in the form of strips of needles wherein the needles are arranged in rows parallel to each other with a belt-like con necting strip between them made of a plastics material.

As the connecting strip, it is known to make use of a plastics material in which the needles are embedded with their ends completely surrounded by the plastics mater ial. However, connecting strips of this kind suffer from the disadvantage that they are considerably wider than the greatest diameter of the needles, which is in the zone of the ends or feet of the needles remote from their tips. Thus, the channels in needle plates for accommodating such needle strips must be quite wide, and this leads to a reduction in the strength or to a necessarily greater width of the needle plates. Furthermore, only relatively thin needles can be used.

It is also known to interconnect the feet of individual needles by means of a plastics material, in particular a polymer, These needle connections do not project laterally beyond the needles in the strip so the strips are more flexible, with the advantage that the channels on the needle plates need not be so wide and that thicker needles can be used.

The plastics material can be compatible with an adhesive for bonding the strip into the channel. However, there arises the problem that because the adhesive, particularly when it is a two-component adhesive, requires a certain time to set, the needles of the strip have to be held in the channel precisely in their required position for that time.

Maintenance of this precise position is made more difficult by the fact that the depths of the channels in needle plates often vary, either because of large manufacturing tolerances, or as a result of repeated milling to remove the remains of used needles to enable the plate to be refitted with new needles.

According to one aspect of the present invention there is provided a retaining plate when used for temporarily supporting the needles of a strip of needles while their ends are secured in a channel of a needle plate with settable adhesive, such retaining plate including a magnetic face having supporting means whereby the plate may be temporarily located on the needle plate with the magnetic face above and parallel to the channel and with an upper edge parallel to the top of the channel and at a distance therefrom corresponding to the desired height of projection of the needles from the needle plate.

The invention also provides the combination of a needle plate having a channel in which the ends of a flexible strip of needles may be inserted, and a retaining plate for temporarily supporting the strip of needles while their ends are secured in the needle plate channel with settable adhesive, said retaining plate including a magnetic face and supporting means to releasably engage the needle plate whereby the retaining plate may be temporarily located on the needle plate with the magnetic face above and parallel to the needle plate channel, and with an upper edge of the retaining plate parallel to the top of the channel.

The invention further provides such a combination wherein said supporting means comprise clips which can be pushed onto and embrace the needle plate and have a stop which determines the required position of the upper edge of the retaining plate relative to the needle plate, such that when the retaining plate is pushed onto the needle plate, one of the limbs of each clip bears against a face of the needle plate which is perpendicular to the length of the channel.

Further the invention provides a method of securing a strip of needles in a channel in a needle plate by locating on the needle plate a retaining plate having a magnetic face so that the said face extends above and parallel to the channel, and such that an upper edge of the retaining plate is disposed parallel to the top of the channel and at a distance from the needle plate corresponding to the desired height of projection of the needles from the plate, inserting the ends of the needles in the channel, aligning the points of he needles with said upper edge, filling the channel with settable adhesive and and removing the retaining plate when the adhesive has set.

The invention allows the needles to be better aligned and brought into the required position in the channel of the needle plate, and permits the needles to be safely held in this required position until the adhesive has set.

Because of the magnetic nature of the side face of the retaining plate, the needles are held over at least part of the length of their stems without danger of damage to their tips. The use of magnetism as the means for retaining the needles means that the needles can be displaced relative to the retaining plate only when a certain force is applied.

Thus, after the retaining plate has been connected to the needle plate and the needles have been placed precisely in their required position on the magnetic side face of the retaining plate, they can be brought into the channel in which they are then retained substantially permanently by the magnetic force. In the position wherein they are held on the magnetic side of the retaining plate, the needle strips can be introduced into the channel of the needle plate without any difficulty at all. The operation of bringing the needle strip, i.e. the needles, into the required position within the channel is considerably facilitated in that the upper edge of the retaining plate extends parallel to the upper surface of the needle plate and at a distance therefrom that corresponds to the required upward projection of the needles when the retaining plate is connected to the needle plate.This greater ease in the positioning of the needles follows from the preferred procedure that the needle strip is first placed, with the needle tips projecting above the upper edge of the retaining plate, on the magnetic side of the retaining plate which has already been brought into its required position relative to the needle plate. For this purpose no special care has to be taken to ensure that the needle strip is of precisely rectilinear form. The needle strip is then automatically located in the overlapping zone of the channel, i.e. it is already partly introduced into the channel.Finally, the tips of the needles projecting beyond the upper edge of the retaining plate are pressed against a flat surface, so that the needles are displaced on the retaining plate in their longitudinal directions until the flat surface encounters the upper edge of the retaining plate, and the tips of the needles are thus aligned with the upper edge of the retaining plate. A substantially parallel equidistant position of the needles in relation to each other is achieved sub stantially automatically also due to the fact that the needles are connected to each other at their feet. The needles of the needle strip then occupy the required position in the channel and are thereafter retained therein.

In this position, the adhesive can be intro duced into the channel or can be topped up without the needle strip moving from the required position, which is retained because of the magnetic force. After the adhesive has set, the retaining plate can be removed from the needle plate, and the needles then become detached from the retaining plate.

Preferably the supporting means are such that a lower edge of the plate is spaced from the needle plate with the retaining plate is located thereon. This enables the channel to be readily reached from both sides, e.g.

for the purpose of topping up the adhesive in the channel.

Preferably also the magnetic face may be formed by a strip of permanently magnetic material secured to the remainder of the retaining plate, and the remainder of the retaining plate is of U-shaped cross-section which imparts a high degree of stability to the retaining plate over its length.

This strip can be secured between the limbs of the U-shape to prevent the means for holding the magnetic strip on the retaining plate from being pulled sideways. An increase in strength can result if the base portion of the U-section is outwardly curved. This assists in providing for the plate to retain its required shape even when acted upon by fairly large forces. Preferably also, the magnetic strip is made of flexible material and is slightly concave on the face defining said magnetic face, the longitudinal axis of the concavity extending in the longitudinal direc tion of the retaining plate. This means that the retaining surface of the magnetic strip has a shape that substantially complements the shape of the stems of the needles which are slightly barrelled or convex on the side where by the needles are attached. This ensures that, as far as possible, the needles lie flush against the retaining strip over the entire length of the overlapping zone with the result that the retaining force of the magnetic strip is optimised.

If, as is preferred, the length of the strip is the same as that of the needle strip, the needle strip can be precisely located in its required position in the longitudinal direc tion of the retaining plate before it is brought into the required position with respect to the needle plate. Alternatively, if the retaining plate is longer than the needle strip, it can have markings to assist in locating the strip.

Preferably, the fixing projections are clips which can be pushed on to and embrace the needle plate and have a stop which determines the required position of the upper edge of the retaining plate relative to the needle plate. This constitutes a particularly simple method of connecting the retaining plate to the needle plate. There may be distance pieces, for instance set screws, between the limbs of the clips which means that the retaining plate has only to be pushed on to the needle plate as far as its stop so as to be automatically located in its required position in relation to the needle plate. The required position of the retaining plate in relation to the needle plate can also be ensured in the longitudinal direction of the needle plate if the clips engage in grooves in the needle plate, and such grooves are usually provided on needle plates near its two ends.When the needle plate is in use, these grooves serve to guide the plate in relation to the frame of the needle machine.

In order that the invention may be more clearly understood, the following description is given, merely by way of example, with reference to the accompanying drawings, in which :- Figure 1 is a side view of a needle strip, Figure 2 is a side view of a retaining plate of the invention, Figure 3 is a side view of a needle plate with a channel formed therein, Figure 4 is a side view of the needle plate with the retaining plate secured thereto in its required position and with a needle strip adhering to the magnetic side of the retaining plate but not yet moved into its required position in relation to the needle plate, i.e. with the tips of the needles still projecting beyond the upper edge of the retaining plate, Figure 5 is a section on line V-V of Figure 4 but showing the needle strip now moved into its required position, and Figure 6 is a section on line V-V of Figure 4 but only through the cross-head of the retaining plate.

The needle strip 1 consists of a plurality of needles 3 which are arranged parallel to each other at a distance 2 apart, and the tips 4 of which are disposed on one and the same line. In the region 5 of their feet, the needles 3 are interconnected by a plastics material consisting of a connector 6 which bridges the gap between each two adjacent needles, the plastics material being a flexible one, e.g. a polymer. The connectors 6 thus constitute belt-like needle strips. The major part of the length of the stem of each needle 3 projects upwards beyond the connectors 6.

The needle plate 7 can be clamped in a needle machine at its two ends 8 and 9. The ends 8 and 8 are interconnected by the crosshead 10 of the needle plate, which cross-head is provided at its upper side face 11 with a channel 12 which is parallel to said side face over the entire length of the cross-head 10 and is closed at its ends. The channel 12 serves to accommodate the feet 5 of the needle strip 1. The needle strip 1, when in the shape it assumes when fitted in the channel 12 is connected to the needle plate 7 by means of a liquid two-component adhesive which is introduced into the channel 12 before or after the needle strip 1 has been fitted and which, after it has set, secures the needle strip 1, i.e. the needles 3, firmly in that position relative to the needle plate 7 that the needles 3 occupy within the channel 12 at the moment when the adhesive sets.

The ends 14 and 15 of the retaining plate 13 serving to retain the needles 3, i.e. the needle strip 1, can be pushed onto and clamped to the ends 8 and 9 of the needle plate 7. For this purpose, the ends 14 and 15 are provided with fixing projections 16 and 17 which extend towards the needle plate 7. The fixing projections 16 and 17 are formed as clips which can embrace the ends 8 and 9 of the needle plate 7. The two limbs of each such clip are designated by the numerals 18 and 19. In particular, the limbs 18 are stamped from the fixing projections 16 and 17 and are bent out therefrom. Between the limbs 18 and 19 a cross-head 20 forms a stop for limiting the distance over which the retaining plate 13 can be pushed on to the needle plate 7.

On one side the ends 8 and 9 of the needle plate 7 have vertical guide grooves 21 and 22 which, when the needle plate is being used, serve to guide it in the needle machine. These guide grooves 21 and 22 can be used for longitudinally guiding the retaining plate 13 when pushed onto the needle plate 7, and for this purpose the limbs 18 of the clips of the retaining plate 13 are so dimensioned and at such distance apart that they can be pushed into the guide grooves 21 and 22 of the needle plate. The distance between the limbs 18 and 19 of the clip of the retaining plate 13 are at such distance apart that, after the retaining plate has been pushed on into the guide grooves 21 and 22, a positive mechanical connection is achieved such that the retaining plate 13 cannot be inadvertently displaced transversely of its longitudinal axis.

The cross-head 23 of the retaining plate 13 interconnects the two fixing projections 16 and 17. It is at least as long as but generally longer than the needle strip 1. The cross-head 23 forms the actual retaining plate 13. In the posilton in which it is pushed on to the needle plate 7, the retaining plate 13 extends above the channel 12 and to the side thereof and parallel to the needle plate 7.

On that of its side faces presented to the the longitudinal plane of symmetry 24 of the channel 12, the retaining plate 13 has a bonded magnetic strip 25 in the zone of its cross-head 23. The part which is here called a "magnetic strip" is a flexible strip of a permanently magnetic material. The crosshead 23 of the retaining plate is of U-shaped cross-section which is open at the end facing the magnetic strip 25. The magnetic strip 25 is placed between and substantially mates with the U-shaped limbs 26 and 27 of the cross-head 23, and is firmly bonded to the base portion between the limbs 26 and 27. The exterior retaining surface of the magnetic strip 25 extends slightly beyond the ends of the limbs 26 and 27 of the U. The base portion 28 of the U is preferably downwardly curved and in particular is provided with an additional corrugation 29.In this way a slightly concave form is imparted to the connecting base portion 28, the axis of bend of the curvature extending parallel to the cross-head 23 of the retaining plate 13. Thus, and because of the flexible form of the magnetic strip 25, the retaining surface 30 of the magnetic strip 25 is likewise slightly concave so that it matches the slightly barrelled or convex form of the needles 3 in the zone thereof presented to the retaining surface 30.

In the fixing position in which it is pushed on to the needle plate 10, the upperedge31 of the retaining plate 13 extends parallel to the upper side face 11 of the needle plate 10 in which the channel 12 is formed, and said upper edge 31 is at a distance from the needle plate that corresponds to the required projection height 32. When the retaining plate 13 is in the pushed-on position, there is also a gap 37 between the lower edge 33 of the retaining plate and the upper side face 11 of the needle plate.

The magnetic strip 25 may be exactly as long as the needle strip 1. However it may be longer and may carry marks for indicating the position of each of the outer needles 3 of the needle strip 1.

The needle strip 1 is secured in the channel 12 in the needle plate 7 in the following manner: The retaining plate 13, without a needle strip attached, is pushed on to the needle plate 7 and is thus brought into its required position. In this required position the retaining plate 13 is secured by the limbs 18 and 19 of the clip inserted in the guide grooves 21 and 22. The needle strip 1 is then placed on the retaining surface 30 of the magnetic strip 25 with the tips 4 projecting above the upper edge 31 of the retaining plate 13.

To facilitate the positioning of the needle strip 1 in relation to the longitudinal direction of the cross-head 23 of the retaining plate 13, use is made of the ends 34 and 35 of the magnetic strip 25 or of markings carried on this strip 25, the needle strip 1 with each of its outwardly projecting needles 3 being aligned with these markings. In this position the needle strip 1 lies in the overlapping zone of the channel 12. It may also project in part into the channel 12 by its foot zone 5.

At this time the channel 12 may already be filled to a sufficient extent with adhesive that has not yet set.

The needle plate 1 i.e. the needles 3 are then moved into their required position in the following simple manner; the unit which is formed by the needle plate 7, with the retaining plate 13 pushed on to it, and by the needle strip 1 adhering to the retaining plate 13 and in which the tips 4 of the needles 3 project above the upper edge 31 of the retaining plate 13, is pushed, by means of the needle tips 4, in the direction of the axes of the needles and towards a plane, e.g.

a bench undersurface, extending perpendicularly to the axes of the needles. In the same way it is possible, using say a flat object e.g.

a steel straight-edge, to push the tips 4 of the needles 3 in the longitudinal direction of the needles and on to the needle plate 10. As this is happening, the needles 3 are displaced on the retaining surface 30 of the magnetic strip 25 without the attraction thereto being broken. This movement of all the needles 3 in unison terminates at the moment when the plane 36 encounters the upper edge 31 of the retaining plate 13. In this position the tips 4 of the needles 3 are precisely aligned with the upper edge 31 of the retaining plate 13. Thus, after the needle tips 4 have been fully acted upon by the plane 36, the distance 32 determines the height of projection of the needles 3 relative to the upper side face 11 of the needle plate 10, In the end position following displacement, the needles 3 continue to adhere to the retaining surface 30 of the magnetic strip 25. In this position, because of the distance 37, further adhesive can be poured in if it is required to fill the channel 12 completely therewith. The adhesive can set over a longer period without any interference with the safe retention of the needles 3 in their required position relative to the needle plate 10.

After the adhesive has completely set, the retaining plate 13 is simply removed from the needle plate 10, and the connection between the needles 3 and the magnetic strip 25 is broken. The needle plate 10 is then in the form in which it is fitted with needles in the prescribed manner.

WHAT WE CLAIM IS: 1. A retaining plate when used for temporarily supporting the needles of a strip of needles while their ends are secured in a

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

Claims

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

plate 7, the retaining plate 13 extends above the channel 12 and to the side thereof and parallel to the needle plate 7.

On that of its side faces presented to the the longitudinal plane of symmetry 24 of the channel 12, the retaining plate 13 has a bonded magnetic strip 25 in the zone of its cross-head 23. The part which is here called a "magnetic strip" is a flexible strip of a permanently magnetic material. The crosshead 23 of the retaining plate is of U-shaped cross-section which is open at the end facing the magnetic strip 25. The magnetic strip 25 is placed between and substantially mates with the U-shaped limbs 26 and 27 of the cross-head 23, and is firmly bonded to the base portion between the limbs 26 and 27. The exterior retaining surface of the magnetic strip 25 extends slightly beyond the ends of the limbs 26 and 27 of the U. The base portion 28 of the U is preferably downwardly curved and in particular is provided with an additional corrugation 29.In this way a slightly concave form is imparted to the connecting base portion 28, the axis of bend of the curvature extending parallel to the cross-head 23 of the retaining plate 13. Thus, and because of the flexible form of the magnetic strip 25, the retaining surface 30 of the magnetic strip 25 is likewise slightly concave so that it matches the slightly barrelled or convex form of the needles 3 in the zone thereof presented to the retaining surface 30.

In the fixing position in which it is pushed on to the needle plate 10, the upperedge31 of the retaining plate 13 extends parallel to the upper side face 11 of the needle plate 10 in which the channel 12 is formed, and said upper edge 31 is at a distance from the needle plate that corresponds to the required projection height 32. When the retaining plate 13 is in the pushed-on position, there is also a gap 37 between the lower edge 33 of the retaining plate and the upper side face

11 of the needle plate.

The magnetic strip 25 may be exactly as long as the needle strip 1. However it may be longer and may carry marks for indicating the position of each of the outer needles 3 of the needle strip 1.

The needle strip 1 is secured in the channel 12 in the needle plate 7 in the following manner: The retaining plate 13, without a needle strip attached, is pushed on to the needle plate 7 and is thus brought into its required position. In this required position the retaining plate 13 is secured by the limbs 18 and 19 of the clip inserted in the guide grooves 21 and 22. The needle strip 1 is then placed on the retaining surface 30 of the magnetic strip 25 with the tips 4 projecting above the upper edge 31 of the retaining plate 13.

To facilitate the positioning of the needle strip 1 in relation to the longitudinal direction of the cross-head 23 of the retaining plate 13, use is made of the ends 34 and 35 of the magnetic strip 25 or of markings carried on this strip 25, the needle strip 1 with each of its outwardly projecting needles 3 being aligned with these markings. In this position the needle strip 1 lies in the overlapping zone of the channel 12. It may also project in part into the channel 12 by its foot zone 5.

At this time the channel 12 may already be filled to a sufficient extent with adhesive that has not yet set.

The needle plate 1 i.e. the needles 3 are then moved into their required position in the following simple manner; the unit which is formed by the needle plate 7, with the retaining plate 13 pushed on to it, and by the needle strip 1 adhering to the retaining plate 13 and in which the tips 4 of the needles 3 project above the upper edge 31 of the retaining plate 13, is pushed, by means of the needle tips 4, in the direction of the axes of the needles and towards a plane, e.g.

a bench undersurface, extending perpendicularly to the axes of the needles. In the same way it is possible, using say a flat object e.g.

a steel straight-edge, to push the tips 4 of the needles 3 in the longitudinal direction of the needles and on to the needle plate 10. As this is happening, the needles 3 are displaced on the retaining surface 30 of the magnetic strip 25 without the attraction thereto being broken. This movement of all the needles 3 in unison terminates at the moment when the plane 36 encounters the upper edge 31 of the retaining plate 13. In this position the tips 4 of the needles 3 are precisely aligned with the upper edge 31 of the retaining plate 13. Thus, after the needle tips 4 have been fully acted upon by the plane 36, the distance 32 determines the height of projection of the needles 3 relative to the upper side face 11 of the needle plate 10, In the end position following displacement, the needles 3 continue to adhere to the retaining surface 30 of the magnetic strip 25.In this position, because of the distance 37, further adhesive can be poured in if it is required to fill the channel 12 completely therewith. The adhesive can set over a longer period without any interference with the safe retention of the needles 3 in their required position relative to the needle plate 10.

After the adhesive has completely set, the retaining plate 13 is simply removed from the needle plate 10, and the connection between the needles 3 and the magnetic strip 25 is broken. The needle plate 10 is then in the form in which it is fitted with needles in the prescribed manner.

WHAT WE CLAIM IS: 1. A retaining plate when used for temporarily supporting the needles of a strip of needles while their ends are secured in a

channel of a needle plate with settable adhesive, such retaining plate including a magnetic face and supporting means to engage the needle plate whereby the plate may be temporarily located on the needle plate with the magnetic face above and parallel to the channel and with an upper edge parallel to the top of the channel and at a distance therefrom corresponding to the desired height of projection of the needles from the needle plate.
2. A retaining plate according to claim 1, in which the supporting means are such that a lower edge of the plate is spaced from the needle plate when the retaining plate is located thereon.
3. A retaining plate according to claim 1 or 2, wherein the magnetic face is formed by a strip of permanently magnetic material secured to the remainder of the plate.
4. A retaining plate according to claim 3, wherein the strip is bonded to the remainder of the plate.
5. A retaining plate according to claim 3 or 4, wherein the magnetic strip is made of flexible material and is slightly concave on the face defining said magnetic face, the longitudinal axis of the concavity extending in the longitudinal direction of the retaining plate.
6. A retaining plate according to any preceding claim, wherein said remainder of the plate is of U-shaped cross-section.
7. A retaining plate according to claim 3, 4 or 5 and claim 6, wherein the U-shaped cross-section of said remainder is open at that side presented to the magnetic side of the retaining plate, and the magnetic strip is placed between and secured within the limbs of the U.
8. A retaining plate according to claim 7, wherein a surface of the magnetic strip, that is the said magnetic face, is located beyond the limbs of the U.
9. A retaining plate according to claim 6, 7, or 8, wherein the base portion of the U-section is outwardly curved.
10. A retaining plate according to claim 9, wherein the base portion of the U-section is provided with an outwardly projecting corrugation.
11. A retaining plate according to any preceding claim, wherein said supporting means comprise fixing projections disposed at the ends of the retaining plate to extend in use towards the needle plate.
12. A retaining plate according to claim 11, wherein the fixing projections are clips which can be pushed on to and embrace the needle plate and have a stop which determines the required position of the upper edge of the retaining plate relative to the needle plate.
13. A retaining plate according to claim 12, including distance pieces, for instance, set screws, between the limbs of the clip.
14. A retaining plate according to claim 12 or 13, wherein one of the limbs of each clip is formed by stamping it out of the other limb and bending it out.
15. A retaining plate according to claim 12, 13 or 14, wherein the fixing projections are integral with the rest of the plate except, where provided, the magnetic strip.
16. A retaining plate according to claim 15 which is made of metal which is stamped or punched.
17. A retaining plate according to any preceding claim wherein the magnetic face has markings whereat the end needles of a strip can be positioned.
18. A retaining plate constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
19. The combination of a needle plate having a channel in which the ends of a flexible strip of needles may be inserted, and a retaining plate for temporarily supporting the strip of needles while their ends are secured in the needle plate channel with settable adhesive, said retaining plate including a magnetic face and supporting means to releaseably engage the needle plate whereby the retaining plate may be temporarily located on the needle plate with the magnetic face above and parallel to the needle plate channel, and with an upper edge of the retaining plate parallel to the top of the channel.
20. A combination according to claim 19, wherein the retaining plate extends over at least the length of the channel.
21. A combination according to claim 19 or 20, wherein said supporting means comprises clips which can be pushed onto and embrace the needle plate and have a stop which determines the required position of the upper edge of the retaining plate relative to the needle plate such that when the retaining plate is pushed onto the needle plate, one of the limbs of each clip bears against a face of the needle plate which is perpendicular to the length of the channel.
22. A combination according to claim 21, wherein the needle plate has, at each end, a guide groove perpendicular to the length of the channel and said face of the needle plate is a face of said channel.
23. The combination of a retaining plate and a needle plate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
24. A method of securing a strip of needles in a channel in a needle plate by locating on the needle plate, a retaining plate having a magnetic face so that the said face extends above and parallel to the channel, and such that an upper edge of the retaining plate is disposed parallel to the top of the channel and at a distance from the needle plate corresponding to the desired height of projection of the needles from the needle plate, inserting the ends of the nedles in the channel, aligning the points of the needles with said upper edge, filling the channel with settable adhesive and removing the retaining plate when the adhesive has set.
25. A method of securing a flexible strip of needles in a channel in a needle plate substantially as hereinbefore described with reference to the accompanying drawings.