JPH0424086A - Upper louver mechanism of sewing machine - Google Patents

Abstract

PURPOSE:To obtain good sliding characteristics by forming a porous hard film over a sliding area of an upper louver mount base to apply fluoroplastics thereto so that said film is impregnated with the fluoroplastics and forming a layer of iron-nitrogen-carbon compound and a nitrogen diffused layer over the sliding area of an upper louver guide. CONSTITUTION:The sliding area, which is to be slidably contacted with an upper louver guide 8, of an upper louver mount base 5 is composed of a mother material 11 made from chrome-molybdenum steel, on the surface of which a porous herd film 12 of nickel-phosphorus alloy with a thickness of 5-25mum is formed by electoless plating and further fluoroplastics 13 are applied into the surface pores in said porous film as deep as about one-third of their depth, in which the hardness of the surface of the film is Hmv 1000-1200. In the upper louver guide 8, a layer 15 of iron-nitrogen-carbon compound with a thickness of 5-10mum and a nitrogen diffused layer 16 with a thickness of 0.1-0.4mm are formed over a mother material 14 made from chrome-molybdenum steel and the hardness of its surface is Hmv 500. As a result, good sliding characteristics can be obtained, without causing seizing or abnormal wear.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an upper looper mechanism for a sewing machine.

[Prior art] Conventionally, the upper looper mechanism of industrial overlock sewing machines was
an upper looper arm that swings in synchronization with the vertical movement of the sewing needle; a substantially shaft-shaped upper looper mounting base having an upper looper fixed to its tip and rotatably connected to its lower end to the upper looper arm; an upper looper guide rotatably supported by the sewing machine housing and formed with a sliding hole through which the upper looper mounting base is slidably inserted in a direction perpendicular to the rotation axis of the upper looper guide;
The upper looper mounting base and upper looper guide were made of metal materials such as alloy steel and ordinary carbon mesh, and were treated as necessary by hardening or hard plating with chromium (Cr), nickel (N1), etc. .

When the upper looper is driven, the upper looper mount is subjected to axial movement and rotational movement. In the past, a large bending stress was applied to the upper looper mounting base, and the upper looper guide that guided it was subjected to tensile stress in the direction of pushing the sliding hole and expanding it in addition to the internal sliding resistance.
Severe wear will occur at very high loads. Therefore, at present, treatments such as hard chromium (Cr) plating are used.

[Problems to be Solved by the Invention] However, large bending stress is generated in the elongated rod-shaped upper looper mounting base, and large tensile stress is applied to the upper looper guide, so that the sliding surfaces of each other are Since a large pressure is applied to the extreme parts of the material, the combination of conventional material 9 surface treatments will result in many sliding marks on the sliding parts, and in some cases, the sliding materials may stick to each other, resulting in seizure or wear particles. Occurrence may result in decreased locking due to decreased clearance.

The present invention was made in order to solve the above-mentioned problems, and its purpose is to obtain good sliding characteristics without causing seizure or abnormal wear, and to prevent breakage even when high stress is applied. The purpose is to provide an upper looper mechanism.

[Means for Solving the Problems] In order to achieve this object, the present invention forms the upper looper mounting base from metal, forms a porous nickel-phosphorus alloy coating on the sliding part, and then coats the surface of the upper looper mount with a porous nickel-phosphorus alloy coating. In addition to impregnating and fusing a fluororesin, the upper looper guide is formed of metal, and an iron-nitrogen-carbon compound layer and a nitrogen diffusion layer are formed on its sliding portion.

[Function] In the present invention having the above configuration, the upper looper mounting base is made of a metal material with high toughness, and a porous hard coating is formed on its sliding portion, and a fluororesin is coated on the surface of the upper looper mounting base. Because it is impregnated and fused, it exhibits good sliding properties without breaking.

On the other hand, the upper looper guide is similarly made of a metal material with high toughness, and its sliding parts have an iron-nitrogen-carbon compound layer that is resistant to wear and corrosion, and a nitrogen diffusion layer that is resistant to fatigue. Because of this structure, it does not break even under high load stress and exhibits excellent sliding characteristics without wear.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of the upper looper mechanism of the industrial overlock sewing machine of this embodiment. The right end of the upper looper arm 2 is fitted onto an upper looper shaft 1 that rotates in synchronization with the vertical movement of a sewing needle (not shown), and is fixed by a bolt 3. Furthermore, the hill looper arm 2 is rotatably connected at its left end to the two lower end prongs of a hollow shaft-shaped upper looper mount 5 via an upper looper arm shaft 4. The upper looper guide 8 has a cylindrical shape and is rotatably supported by an upper looper guide metal 9 fixed to a sewing machine housing (not shown), and its movement in the axial direction is restricted. Further, the upper looper guide 8 has a sliding hole 10 in a direction perpendicular to its axial direction, and the upper looper mounting base 5 is inserted through the sliding hole 10 so as to be able to reciprocate in the axial direction. There is. Moreover, an upper looper 6 is fixed to the upper end of the looper mount 5 with screws 7.

The sliding portion of the upper looper mounting base 5 with the upper looper guide 8 is formed of a base material 11 made of chromium molybdenum steel, as shown in the partially enlarged sectional view of FIG. A hard coating 12 of nickel-phosphorus alloy with a thickness of 5 to 25 mm is formed by electroless plating, and the surface pores of the coating 12 are coated with fluororesin 13 to a depth of about 1/3 of the coating thickness. It is impregnated and fused, and the hardness of the film surface is Hmv 100CI-1200. As shown in the partially enlarged sectional view of FIG. 3, the upper looper guide 8 has a base material 14 made of chromium molybdenum steel, a 5-10 layer iron-nitrogen-carbon compound layer 15, and a 0.1-0.0 mm thick iron-nitrogen-carbon compound layer 15. A 4 mm thick nitrogen diffusion layer 16 is formed, and the hardness is Hmv500.

In the upper looper mechanism configured as described above, the upper looper shaft 1 rotates at a certain rotation angle in synchronization with the vertical movement of the sewing needle (not shown). Arm 2 swings at a certain angle. As a result, the upper looper mounting base 5 connected to the swinging end of the upper looper arm 2
While reciprocating in the sliding hole 10 of the upper looper guide 8, it rotates at a constant angle about the axis of the upper looper guide 8. Due to this operation, the upper looper 6 fixed to the upper end of the upper looper mount 5 reciprocates toward the upper left in the drawing.

Due to such movement, a large bending stress is applied to the upper looper mounting base 5, and in addition to the sliding resistance on the inner surface, the upper looper guide 8 that guides it is subjected to tensile stress in the direction of pushing and expanding the sliding hole 10. The base material 11 of the upper looper mounting base 5 is made of highly tough chromium molybdenum steel, on which a porous nickel-phosphorus alloy coating 12 is formed, and the surface thereof is impregnated with fluororesin 13. Since it is fused, it does not break and exhibits good sliding characteristics.

On the other hand, the upper looper guide 8 is made of chromium molybdenum steel with high toughness, and has an iron-nitrogen-carbon compound layer 15 and a nitrogen diffusion layer 16 formed on its sliding portion, so it is not subject to high load stress. It exhibits excellent sliding properties without breaking or wearing out.

In order to compare the wear resistance and seizing resistance between the upper looper guide 8 and the upper looper mounting base 5 which have been subjected to the above-mentioned treatment of this embodiment with those treated with other treatments, FIG. A sliding abrasion test was conducted.

In this test, a pin (targeted for the upper looper mounting base) and a block (corresponding to the upper looper guide) with a surface roughness of 1.6Rz are prepared, and a load (P) is applied by pressing the block against the pin.
Apply a load of IKgf to dry state, and in this state slide the pin against the block at a speed (V=) of 1 m/s e
Slide back and forth for 10 man strokes at c (average),
The sliding time was set to 2 minutes. Since the surface and speed change with Vosinωt, average values are shown.

The reciprocating speed is 3000 cycles/min. After performing the above-mentioned reciprocating sliding for 2 minutes, the friction force was measured and used as a criterion for determining seizure resistance, and the abrasion resistance of both the pin and block at that time was measured and used as a criterion for determining wear resistance. FIG. 5 shows the average value obtained when the above test was conducted twice. As is clear from FIG. 5, a porous nickel-phosphorus alloy coating 12 is formed on the upper looper mounting base, a fluororesin 13 is formed on its surface, and the upper looper guide is subjected to soft nitriding treatment. It can be seen that the combination in which the carbon compound layer 15 and the nitrogen diffusion layer are formed has the best wear resistance. It can also be seen that the seizure resistance at that time is also good.

[Effects of the Invention] As is clear from the detailed description above, according to the upper looper mechanism of the present invention, the upper looper mounting base is formed of metal,
After forming a porous hard coating on the sliding part, its surface is impregnated and fused with fluororesin, the upper looper guide is formed of metal, and an iron-nitrogen-carbon compound layer is formed on the sliding part. Since a nitrogen diffusion layer is formed, good sliding characteristics can be obtained without causing seizure or abnormal wear, and the excellent effect of not breaking even when high stress is applied can be achieved.

[Brief explanation of the drawing]

1 to 3 show an embodiment embodying the present invention. FIG. 1 is a sectional view of the upper looper mechanism of an industrial overlock sewing machine, and FIG. 2 is a surface of the upper looper mounting base. FIG. 3 is a partially enlarged sectional view of the surface of the upper looper guide, FIG. 4 is a schematic diagram showing the friction and wear tester, and FIG.
The figure is a table showing the results of friction and wear tests for wear resistance and seizure resistance for various materials and treatments. In the figure, 2 is an upper looper arm, 5 is an upper looper mounting base, 6 is an upper looper, 8 is an upper looper guide, 10 is a sliding hole, 12 is a hard coating, 13 is a fluororesin, 15 is a compound layer, ]6 is the diffusion layer.

Claims (1)

[Claims] 1. An upper looper arm 2 that swings in synchronization with the vertical movement of the sewing needle;
an upper looper mount 5 having a substantially shaft-like shape, with an upper looper 6 fixed to its tip and rotatably connected to the upper looper arm 2 at its lower end;
is rotatably supported by the sewing machine housing, and
In an upper looper mechanism of a sewing machine, the upper looper guide 8 is provided with an upper looper guide 8 formed with a sliding hole 10 through which the upper looper mount 5 is slidably inserted in a direction perpendicular to the rotation axis thereof. The table 5 is made of metal, a porous hard film 12 is formed on its sliding portion, and then a fluororesin 13 is impregnated and fused on the surface thereof, and the upper looper guide 8 is made of metal. An upper looper mechanism for a sewing machine, characterized in that an iron-nitrogen-carbon compound layer 15 and a nitrogen diffusion layer 16 are formed on a sliding part.