TWI766180B - Compound needle for a warp knitting machine - Google Patents

Abstract

A compound needle (1) for a warp knitting machine is specified with a needle head (2), which has a hook (3), with a transition region (4) which adjoins the hook (3) and the cross section of which increases in a direction away from the needle head (2), and with a stem (5).

It is possible to be able to reliably operate a warp knitting machine even with threads which are difficult to process.

For this purpose, it is provided that the transition region (4) has an edge profiling (14, 15) which changes continuously between the hook (3) and the stem (5).

Description

Duplex needles for warp knitting machines Field of Invention

The present invention relates to a compound needle for warp knitting machines having a needle with a hook with a transition area adjoining the hook, the cross-section of the transition area increasing in a direction away from the needle , accompanied by a stroke.

Background of the Invention

Such a double needle for warp knitting machines is known, for example, from DE 25 37 502 A1.

During operation of the warp knitting machine, the compound needles must absorb forces during loop formation. For example, the compound needle is loaded to bend sideways due to thread transfer, due to thread tension and fabric detachment in the machine and transverse directions, and due to the rise of the compound needle, during which the compound needle undergoes a loop loop, which must slide out of the area of the hook to the rod, to a compressive load in one of the longitudinal axes.

Duplex needles are produced, for example, by stamping from sheet metal or by hammering from wire. After punching, burrs must be removed, which can occur, for example, due to vibratory grinding. Again, in the process remove all sharp edges The edges are slightly rounded.

The above-mentioned loads to which the compound needles are subjected also depend inter alia on the thread used to produce the knitted article. The less compliant the wires are, the greater the loads are generally. For example, if it is intended to produce mosquito nets, relatively stiff monofilaments are used for the threads. Even though the goodness is relatively low, the loads experienced by the compound needles during operation of the warp knitting machine are so great that failures that can even extend to the destruction of the compound needles are increasingly occurring.

Summary of Invention

The present invention is based on the goal of being able to operate the warp knitting machine reliably even with difficult threads.

This object is achieved in the case of a double needle for warp knitting machines of the type mentioned at the outset, in which the transition region has an edge profile that changes continuously between hook and bar.

The design of the compound needle can thus be substantially unchanged. The multiple needles may in particular have a reinforced design up to a certain limit in order to be able to absorb the loads caused by the thread to be treated. However, to provide the double needle in a targeted manner with a predetermined edge profile, the predetermined edge profile can be produced, for example, by means of a machining step. As an alternative to this, edge profiles can also be produced by pressing. The effect that can be achieved by the edge profile is that the loop formed at the hook can easily slide onto the rod when the compound needle is raised.

The edge profile is preferably in the form of a rounded corner. The movement of the loop from the hook onto the rod is thus further facilitated.

The fillet preferably has a curve that increases away from the hook Rate. The transition region has a cross-section that increases from the hook to the rod. Parallel to the increase in the cross-section, the curvature of the edge profile also increases in a direction away from the hook, and thus the transition region becomes increasingly "angled". However, sharp corners are not actually formed.

Alternatively or additionally, the edge profile may be in the form of a bevel. A mix of rounded and beveled corners is possible. An increased curvature corresponds to a decreased bevel width.

In a preferred refinement, a ratio between an area determined by a width and a depth of the transition region and a cross-sectional area of the transition region increases from the hook to the rod. This condition applies at any distance from the hook. In other words, the closer to the hook, the larger one of the areas, as determined by the width and the depth of the transition area, is left open by the edge profile. The width here is the direction in which the double needles are arranged next to each other in the beams of the warp knitting machine. The depth is perpendicular to it and perpendicular to the direction of the longitudinal extension of the compound needle.

The ratio at the transition region adjacent to a first end of the hook is preferably a maximum of 0.8. In other words, the actual cross-sectional area of the transition region occupies only 80% of the area that would actually be available due to the product of the width and depth of the transition region.

There is also the advantage that the ratio at a second end of the rod adjacent to the transition region is at least 0.85. The edge profile here has the effect that a maximum of 15% of the area, determined by the width and the depth of the transition region, is not covered by the cross-section of the transition region.

Preferably, a front side of the compound needle has a first edge profile, and a rear side of the compound needle has a second edge profile, wherein the The first edge profile is different in design from the second edge profile. Consider therefore the fact that the front side of the compound needle forms a groove in which the slider moves during operation of the warp knitting machine.

The first edge profile preferably has a maximum first radius of curvature that is less than a thickness of a wall enclosing a slide bar groove. The edge profile thus ends before it reaches the slider groove. The geometry of the slider groove can thus remain unchanged.

In a preferred refinement, the second edge profile is provided to have a maximum second radius of curvature that falls within the range of 10% to 30% of a width of the double needle. The maximum second radius of curvature is therefore relatively large.

There is also an advantage if the edge profile continues in the rod. It can thus gradually disappear in the rod, ie it does not have to stop directly at the end of the transition area.

It is also advantageous that the edge profile is limited to a loop-forming area of the compound needle. The loop forming area corresponds substantially to the lift or lift height of the compound needle during operation of the warp knitting machine. Stretching beyond one of its edge profiles is not required.

1: double needle

2: Needle

3: hook

4: Transition area

5: Rod

6: Needle butt

7: Crossbar resting surface

8: The back side of the needle

9: The front side of the needle

10: Slider groove

12: Ring forming area

13: Location

14: The first edge profile, edge profile

15: Second edge profile, edge profile

16: Left wing

17: Right wing

18, 19: Wall

A, B: area

CC, DD: Profile line

The invention will be described below with reference to preferred exemplary embodiments in conjunction with the drawings, in which: Figures 1a and 1b show a perspective illustration of a compound needle for a warp knitting machine from two viewing directions, and Figures 2a and 2b show Enlarged representation of the compound needle in areas A and B according to Fig. 1 between the needle and the stem, Figures 3a-3c show a side view and two cross-sectional views of a compound needle.

In all figures, the same elements are provided with the same reference numerals. Figures 1a and 2a here show the compound needle from the left rear, while Figures 1b and 2b show the compound needle from the right front.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The compound needle 1 for a warp knitting machine has a needle 2 with a hook 3 .

The hook 3 is adjoined by a transition region 4 whose cross-section increases in a direction away from the needle 2 . The transition area 4 is adjoined by a rod 5 of which a butt 6 is arranged at its end facing away from the needle 2 . The rod 5 has a bar rest surface 7 adjacent to one of the butts 6 .

Figure 1a shows the needle rear side 8, while Figure 1b shows the needle front side 9. A slider groove 10 is formed in the front side 9 . During operation of the warp knitting machine, the slider groove serves to receive a slider by which the needle pulls the thread through the loops previously formed on the loop-forming area 12 during the loop-forming operation. The slider closes the capture space 11 .

As can be seen, the cross section of the transition region 4 increases from the needle 2 towards the stem 5 . Therefore, when the compound needle 1 is raised for the next loop forming operation, the loops already formed in the area of the needle 2 must widen in order to pull the warp thread again through the loops previously formed on the compound needle. This is generally known.

In the case of difficult threads (because they are relatively stiff), large forces act on the compound needle 1 during this loop-forming operation. of the line The transfer causes the compound needle 1 to be loaded to be bent sideways, that is, in the width direction. The compound needle 1 is loaded in the longitudinal and depth directions by thread tension and fabric removal. The shape of the compound needle 1 is such that the compound needle 1 is subjected to a compressive stress on the longitudinal axis as it rises due to the sliding of the loop from the needle 2 onto the rod 5 . The process material (ie the wire or the loop formed) is also subjected to dangerous stresses during the ascent, since the loop has to slide from the needle 2 onto the rod 5 and widen greatly in the process. This widening can occupy three times the size of the loop.

This stress can be absorbed only to a limited extent by the reinforcement of the compound needle 1 . Reinforcement of the width of the compound needle 1 (that is, reinforcement parallel to the crossbar rest surface 7) is only possible to a limited extent, since the thickness of the compound needle 1 that can be affected by this reinforcement is usually determined by the fineness (also That is, the number of double needles per inch) to determine. Reinforcement in the depth direction (ie in the direction between the rear side 8 and the front side 9 ) is likewise only possible to a limited extent. Furthermore, the transition between needle 2 and stem 5 cannot be made over a very short distance, since the loop would then have to widen too quickly.

Another way is now chosen for keeping the load of the compound needle 1 low during the widening of the loop. The compound needle 1 is provided with an edge profile which changes continuously between the hook 3 (ie the needle 2 ) and the stem 5 . This continuous change does not have to take place here over the full distance between the needle 2 and the rod 5 . However, it should occur in the loop forming region 12 where the loop has widened during operation. This portion extends from needle 2 approximately as far as position 13 . However, the positions 13 can also be located at different points for different types of compound needles 1 . The loop forming portion 12 conventionally has a length of 7 mm to 17 mm.

The edge profile consists of a first on the front side 9 of the compound needle 1 The edge profile 14 is formed by a second edge profile 15 on the rear side 8 of the compound needle 1 . The first edge profile 14 differs from the second edge profile 15 in design.

The first edge profile 14 and the second edge profile 15 may be in the form of rounded corners, for example. The fillet may follow a circular line in cross section, even if this is not absolutely necessary. Circle lines are used for the purpose of simplifying explanation. That is, a radius of curvature can be defined here. More generally, the edge profiles 14 , 15 each have rounded corners, wherein the special feature here is that each rounded corner in each case has a curvature that increases away from the hook 3 . This means, with reference to the curvature in the form of a circular line, which decreases in the direction away from the needle 2 .

Instead of rounded corners, the first edge profile 14 and the second edge profile 15 can also be in the form of beveled corners. One of the edge profiles 14, 15 may be in the form of rounded corners and the other edge profile 14, 15 may be in the form of a bevel, or in one or both of the edge profiles 14, 15, rounded corners are allowed Merge into bevels, or vice versa. This increased radius of curvature then corresponds to the decreased width of the bevel, ie the edge profile then becomes "sharper".

It is now possible to define an area formed from the product of a width (ie the distance between the left 16 and right side wings 17 ) and a depth (ie the distance between the front side 7 and the rear side 8 ). This area can be set as a ratio to the cross-sectional area of the transition region 4 at the same location. The ratio now increases from hook 3 to rod 5 .

The ratio at the transition zone 4 adjacent to the first end of the hook 3 may thus be at most 0.8, ie the cross-sectional area is 80% of the area defined by the product of width and depth. At the other end of the transition zone 4, the ratio may be at least 0.85, ie the cross-sectional area here is the product of the width and the depth at least 85% of the area formed by the product.

As can be seen in the figures, the second edge profile 15 has a smaller curvature on the rear side 8 , ie a larger radius of curvature than the first edge profile 14 on the front side 9 of the compound needle 1 .

The radius of curvature of the first edge profile is limited in particular by the slider groove 10 . A slider groove 10 is formed between the two walls 18 , 19 . The first edge profile 14 in each case has a maximum first radius of curvature which is less than a thickness of the walls 18 , 19 enclosing the slide bar groove 10 .

In contrast, the second edge profile has a maximum second radius of curvature that falls within the range of 10% to 30% of the width of the compound needle 1 (ie, the distance between the left and right wings 16 and 17 ) Inside.

In a manner not specified, the edge profiles 14 , 15 may continue in the rod 5 . However, as explained above, the edge profiles 14 , 15 are sufficiently limited to the loop forming area 12 of the compound needle 1 .

The hook 3 generally has a circular cross section. At least the hook 3 likewise has an edge profile with a corresponding curvature. It can now be ensured that the first edge profile 14 , and in particular also the second edge profile 15 , merge continuously into the hook 3 .

Figure 3 shows a side view of the compound needle 1, in which two cross-sectional views CC and DD can be seen. Figure 3b shows a cross-sectional view of the compound needle 1 along the line CC. Figure 3c shows a cross-sectional view of the compound needle 1 along line DD. By comparing Fig. 3b with Fig. 3c, the change of the edge profile can be clearly seen.

1: double needle

2: Needle

3: hook

4: Transition area

5: Rod

6: Needle butt

7: Crossbar resting surface

8: The back side of the needle

12: Ring forming area

13: Location

15: Second edge profile, edge profile

16: Left wing

A: area

Claims (9)

A compound needle for a warp knitting machine, the compound needle having a needle head having a hook with a transition area adjoining the hook, the cross section of the transition area increasing in a direction away from the needle head, and is accompanied by a lever, wherein the transition region has an edge profile that varies continuously between the hook and the lever, wherein the edge profile is in the form of a rounded corner, and wherein the rounded corner has a distance away from the The hook increases one of the curvatures. 2. The compound needle of claim 1, wherein a ratio between a cross-sectional area of the transition region and an area determined by a width and a depth of the transition region increases from the hook to the stem. The double needle of claim 2, wherein the ratio at a first end of the transition region adjacent to the hook is at most 0.8. The compound needle of claim 2 or 3, wherein the ratio at a second end of the stem adjacent the transition region is at least 0.85. The compound needle of claim 1 or 2, wherein a front side of the compound needle has a first edge profile, and a rear side of the compound needle has a second edge profile, wherein the first edge profile and the The second edge profile is different in design. The compound needle of claim 5, wherein the first edge profile has a maximum first radius of curvature that is less than a thickness of a wall surrounding a slide bar groove. The double needle of claim 5, wherein the second edge profile has a width within a range of 10% to 30% of a width of the double needle A maximum second radius of curvature. The compound needle of claim 1 or 2, wherein the edge profile continues in the stem. The compound needle of claim 1 or 2, wherein the edge profile is limited to a loop-forming area of the compound needle.

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