JP2004121882A - Needle bar driving device of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a needle bar driving device of a sewing machine capable of being positively driven even under no supply of oil and contributing to a stable sewing operation. <P>SOLUTION: A needle bar driving device of a sewing machine has a needle bar 11 which is supported in such a way that it can be moved up and down by bearing members 13, 14. The needle bar 11 is made of a metallic material as its base material and formed such that a film coating of thickness 12 of about 0.1 to 5μm by DLC is applied on a substrate material of the sliding surfaces with the bearing members 13, 14. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a needle bar driving device for a sewing machine, and more particularly, to a needle bar driving device for a sewing machine which enables so-called oilless operation.

The needle bar driving device is for converting the rotational motion of the upper shaft into the translational motion of the needle bar. A conventional needle bar driving device will be described with reference to FIG.

In FIG. 2, a needle 2 is projected from a lower end of a needle bar 1 serving as a shaft member extending vertically, and the needle bar 1 is made of a steel member, a copper alloy, a sintered alloy or the like serving as a bearing member. The needle bar upper metal 3 and the needle bar lower metal 4 are supported movably in the axial direction. At an intermediate position in the axial direction of the needle bar 1, a needle bar holder 5 is fixed so as to be able to move integrally with the needle bar 1. The needle bar holder 5 rotates the upper shaft (not shown) by a crank mechanism. The angular motion is transmitted after being converted into a vertical motion through the needle bar 1 and moves up and down together with the needle bar 1 along a guide groove (not shown).

In such a conventional needle bar driving device, lubricating oil is supplied to the inside of the needle bar upper metal 3 and the needle bar lower metal 4 via a center hole formed in the upper shaft. ing.

In the conventional needle bar driving device described above, lubricating oil was indispensable as described above. However, since lubricating oil cannot be supplied indefinitely, the amount of lubricating oil has been conventionally adjusted.

(5) If the adjusted amount of refueling is too small, seizure may occur, and if the amount of refueling is too large, the problem of oil leakage always accompanies the needle bar driving device.

As described above, various problems have occurred when lubrication is required. Therefore, it has been desired that the needle bar driving device of the sewing machine be lubricated without lubrication.

Further, the needle bar driving device of another sewing machine has a needle bar made of an aluminum alloy as a base member as a shaft member, and a hard alumite coating is generated on a surface of the needle bar made of the aluminum alloy. In addition, a needle bar is formed by impregnating with tetrafluoride resin or molybdenum disulfide (for example, see Patent Document 1). The sliding bearing as the bearing member in Patent Document 1 is made of a polyimide-based or polyimide-amide-based synthetic resin.

When such a needle bar driving device described in Patent Document 1 is driven without lubrication, especially at high speeds, the layer of the tetrafluoride resin or molybdenum disulfide of the needle bar immediately peels off due to abrasion, resulting in abrasion. In addition to the generation of a large amount of powder, the clearance between the needle bar and the sliding bearing becomes large, making it impossible to perform stable sewing.The sliding bearing made of synthetic resin has poor mechanical strength and thermal expansion There was also a problem that it was easy to do.

JP-A-2-109592

 In view of the foregoing, an object of the present invention is to provide a needle bar drive device of a sewing machine that can be driven reliably without oiling and contribute to stable sewing.

In order to achieve the above-described object, a needle bar driving device for a sewing machine according to the present invention has a needle bar driving device having a needle bar supported by a bearing member so as to be vertically movable. Is that a coating having a thickness of 0.1 to 5 μm is formed by DLC on the base material on the sliding surface with the bearing member.

As described above, according to the present invention, it is possible to reliably drive even without lubrication and to contribute to stable sewing. Further, since there is no lubrication, there is no danger of the cloth being stained by oil.

FIG. 1 shows an embodiment of a needle bar driving device of the present invention. In the needle bar driving device of the present embodiment, a needle bar 11 serving as a shaft member has a base material made of steel, A DLC coating 12 as an example of a ceramic material coating having a thickness of 0.1 to 5 μm is formed on the needle bar 11 by an ion plating method.

セ ラ ミ ッ ク In addition, the ceramic material film is desirably CrN, TiN, TiC, TiAlN, BN, or the like in addition to the DLC described above. Among them, CrN, TiN, TiC, and TiAlN preferably have a thickness of 0.2 to 50 μm, and BN preferably has a thickness of 0.1 to 5 μm.

On the other hand, the needle bar upper metal 13 and the needle bar lower metal 14, which support the needle bar 11 so as to be slidable, have their base materials formed of steel, respectively. A bush 15 made of a polyimide-based synthetic resin alone or a synthetic resin material obtained by adding a solid lubricant to this polyimide-based synthetic resin is fitted to the inner peripheral surface of the lower metal 14 that slides with the needle bar 11. ing. Examples of the compounding of the solid lubricant in the bush 15 include a polyimide synthetic resin to which 5 to 60% by weight of graphite is added, and a polyimide synthetic resin to which 5 to 40% by weight of graphite and 5 to 30% by weight of fluorine are added. It is desirable to add a resin or a polyimide synthetic resin to which 5 to 30% by weight of a fluororesin is added.

According to the needle bar upper metal 13 and the needle bar lower metal 14 having the bush 15 made of such a polyimide synthetic resin alone or a synthetic resin material obtained by adding a solid lubricant to the polyimide synthetic resin, the needle bar 11 as the shaft The maximum PV value in sliding with the needle bar is 40 kgf / cm ² · m / s. In particular, the coefficient of friction with the needle bar 11 having the CrN coating as an example of the ceramic material coating is 0.2 or less, and the heat generation is small. In addition, the amount of wear can be reduced.

In general, an average P value of a bearing member in a needle bar driving device of an industrial sewing machine is about 0.4 kgf / cm ² at a rotational speed of 4000 spm, and a peripheral speed is about 4.8 m / s. Therefore, the PV value in this case is about 1.92 kgf / cm ² · m / s, and even if the factors of safety and wear are taken into consideration, the operation without lubrication is sufficiently possible up to a rotation speed of about 4000 spm.

The present invention is not limited to the above-described embodiment, and various changes can be made as needed.

1 is a sectional view showing an embodiment of a needle bar driving device of a sewing machine according to the present invention. A perspective view showing a conventional needle bar driving device of a sewing machine.

Explanation of reference numerals

11 Needle bar 12 DLC coating 13 Needle bar upper metal 14 Needle bar lower metal 15 Synthetic resin bush

Claims (1)

In a needle bar driving device of a sewing machine having a needle bar supported by a bearing member so as to be vertically movable, the needle bar is formed of a metal material as a base material on a base material on a sliding surface with the bearing member by DLC. A needle bar driving device for a sewing machine, wherein a film having a thickness of 1 to 5 μm is formed.