JP2000140470A - Sewing machine and manufacture of sewing machine component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the wear and burning of a sliding component and to cope with the acceleration of an operation speed by forming a coating layer with diamond-like carbon put on a sliding surface through an intermediate layer. SOLUTION: A sewing machine component 1 is a bar-shaped member composed of a metal such as chrome molybdenum steel and a heat treatment layer 10 is formed so as to increase the hardness on the surface. Also, on the surface of the heat treatment layer 10, the coating layer 12 made of the diamond-like carbon is attached through the intermediate layer 11. The intermediate layer 11 improves the attaching strength of the coating layer 12 to the heat treatment layer 10. Thus, the generation of burning in a sliding part is evaded, the durability of the sewing machine component is improved and the stable high-speed operation is made possible over the long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine provided with a sliding part having a coating layer for preventing abrasion and seizure formed on a sliding surface with another part, and a sliding surface of the sliding part. And a method for forming the coating layer.

[0002]

2. Description of the Related Art In recent industrial sewing machines, the operating speed has been increased in order to improve the efficiency of sewing work. In realizing such a high speed, it is important to reduce wear of sliding parts existing in each part of the sewing machine and prevent occurrence of seizure.

In order to prevent the occurrence of wear and seizure, it is effective to increase the hardness of the sliding surface. Conventionally, a high-hardness metal material such as chrome molybdenum steel (JIS SCM415) is used as a material of a sliding component that slides at a high speed with respect to other components such as a needle bar and a looper bar.
Further, measures are taken to increase the hardness by performing a heat treatment such as carburizing, quenching and tempering on these sliding surfaces.

[0004] However, even when subjected to such heat treatment, actually obtained hardness is at most H _v (Vickers ^{hardness) = 750~800 (kgf / mm 2} ) about, sewing speed in recent years of the sewing machine However, there is a problem that it is not possible to sufficiently cope with the demand for higher speed, and further higher hardness is strongly desired.

To meet such a demand, Japanese Patent Laid-Open Publication No.
No. 1076 discloses a technique for further increasing the hardness by coating the surface of a heat-treated sliding part with a high-hardness ceramic layer such as titanium nitride (TiN) or titanium carbide (TiC). It has been disclosed. The hardness of such ceramic _{layer, H v = 2000 (kgf /} mm 2) reaches to the front and rear, which is assumed capable of meeting a certain extent on the sewing machine speed requirements in recent years.

[0006]

However, the ceramic layer as described above is formed by a PVD (physical vapor deposition) method.
Desirably, a processing temperature of about 400 to 450 ° C. is required, and since this processing temperature is higher than the tempering temperature (200 ° C. to 250 ° C.) in the heat treatment described above, sliding as a base material in the process of forming the ceramic layer is performed. The surface hardness of the part is
_Hv = 500 (kgf / mm ² ), and there is a problem that the sewing precision is deteriorated due to the deformation of the sewing machine part due to the effect of the processing temperature.

When such a decrease in hardness occurs, the surface of the sewing machine component is easily locally deformed by a load applied via the ceramic layer during operation of the sewing machine, and the ceramic layer covering the deformed portion is peeled off. In addition, there is a high possibility that abrasion and seizure occur in the peeled portion. In order to solve this problem, JP-A-6-71076 discloses that a plating layer of NiP, NiB or the like having a higher hardness is formed on the surface of a sewing machine component, and the above-described ceramic is formed on the surface of the plating layer. It has been proposed to adopt a two-layer structure in which layers are formed to reduce the difference in hardness between the layers. In this case, a plating process for forming a plating layer and a film forming process for forming a ceramic layer are performed. Also required.

On the other hand, in the formation of the ceramic layer, a processing temperature of about 400 to 450 ° C. is still required, so that the problem that the shape accuracy of the sewing machine component is deteriorated is not solved. When shape inspection is performed on all products and a shape defect occurs, it is necessary to perform additional processing for shape correction on the surface of the high-hardness ceramic layer, and a large number of man-hours are required for these inspections and processing. There was a problem of cost.

Further, since it is inevitable that the surface roughness of the ceramic layer is lower than the surface roughness of the sewing machine component as a base material, when the ceramic layer is incorporated in a sewing machine,
Local sliding resistance is added to the surface of the ceramic layer, and H
Despite having a surface hardness of about _v = 2000 (kgf / mm ² ), there is a problem that a satisfactory effect of reducing wear cannot be obtained.

This problem can be alleviated by increasing the amount of lubricating oil supplied to the sliding portion. For example, when the amount of lubricating oil of the needle bar that slides up and down at the end of the sewing machine arm is increased. In addition, the lubricating oil may be scattered to the outside as the needle bar moves up and down, thereby contaminating sewing products sewn below the sewing machine arm. Therefore, increasing the supply amount of the lubricating oil is not a desirable measure.

The present invention has been made in view of such circumstances, and effectively prevents the wear and seizure of sliding parts such as a needle bar, a looper bar and the like, and responds to an increase in operating speed. An object of the present invention is to provide a sewing machine to be obtained and to provide a method of manufacturing a sewing machine component used for the sewing machine.

[0012]

According to a first aspect of the present invention, there is provided a sewing machine provided with a sliding part having a coating layer formed on a sliding surface with another part, wherein the coating layer is formed of the sliding part. It is characterized by being formed of diamond-like carbon applied to the surface via an intermediate layer.

In the present invention, a coating layer made of diamond-like carbon (DLC) having a higher hardness than ceramics such as TiN or TiC is formed on the sliding surface of another sliding component via an intermediate layer, Effectively prevent seizure. The coating layer made of diamond-like carbon is formed by a plasma CVD method in a reaction gas atmosphere containing carbon.
It can be formed at a low temperature of about 150 ° C to 200 ° C,
A decrease in hardness and a deterioration in shape accuracy of the target component due to the influence of the processing temperature are suppressed, and additional processing for shape correction is not required. The coating layer made of diamond-like carbon is
Due to the action of the intermediate layer, it is possible to adhere the sliding surface of the sliding component with high strength. Diamond-like carbon constituting the coating layer is a carbon of amorphous having a similar structure and properties to the _{diamond, H v = 2000 (kgf /} mm
² ) It has the above hardness and excellent abrasion resistance.
Has a very small coefficient of friction and self-lubricating properties,
Wear can be reduced without requiring a large amount of lubricating oil.

[0014] In the sewing machine according to the second invention, the intermediate layer may include:
It is characterized by comprising a single layer of silicon, titanium, tungsten, titanium carbide, silicon carbide or chromium carbide.

In the present invention, a material having excellent adhesion between the sliding surface of the sliding component and the coating layer made of diamond-like carbon, that is, silicon, titanium, tungsten, titanium carbide A single intermediate layer made of silicon carbide or chromium carbide is interposed, and a coating layer made of diamond-like carbon is simply formed with high adhesion strength.

Further, in the sewing machine according to a third aspect of the present invention, in the sewing machine, the intermediate layer is formed of a material mainly composed of chromium or titanium and the first layer on the sliding surface side, and the coating is composed mainly of silicon or germanium. And a second layer on the layer side.

In the present invention, a first material mainly composed of chromium or titanium and made of a material having excellent adhesion to the sliding surface is provided between the sliding surface of the sliding component and the coating layer made of diamond-like carbon. An intermediate layer having a two-layer structure including a first layer and a second layer mainly composed of silicon or germanium and made of a material having excellent adhesion to the first layer and the coating layer. Is further enhanced.

Further, a sewing machine according to a fourth aspect of the present invention is characterized in that the coating layer is formed on outer surfaces of a needle bar and a looper bar.

According to the present invention, diamond-like carbon is applied to the outer surface of a needle bar that slides at a high speed and the outer surface of a looper bar that performs a complex operation combining sliding and rocking under a high load. To prevent wear and seizure.

A first method for manufacturing a sewing machine component according to the present invention is a method for manufacturing a sliding component of a sewing machine having a diamond-like carbon coating layer formed on a sliding surface with another component, Arranging the sliding component having the cleaned sliding surface in a vacuum chamber, evacuating the vacuum chamber, introducing argon gas into the evacuated vacuum chamber to ionize the silicon, silicon, A step of forming an intermediate layer on the sliding surface by a sputtering process using titanium, tungsten, titanium carbide, silicon carbide or chromium carbide as a target, and discharging the argon gas inside the vacuum chamber, into the vacuum chamber. A step of introducing a reaction gas containing carbon, and a step of converting the reaction gas introduced into the vacuum chamber into plasma, and forming a diamond-like carbon on the surface of the intermediate layer by a plasma CVD process. Characterized in that it comprises a step of forming a coating layer.

A second method for producing a sewing machine component according to the present invention is a method for producing a sliding component of a sewing machine having a diamond-like carbon coating layer formed on a sliding surface with another component, Arranging the sliding component having the cleaned sliding surface in a vacuum chamber, evacuating the inside of the vacuum chamber, introducing argon gas into the evacuated vacuum chamber to ionize the chromium or Forming a first layer on the sliding surface by a sputtering process using titanium as a target, and subsequently performing the first process by using a sputtering process using silicon or germanium as a target.
A step of forming a second layer on the surface of the layer, a step of discharging argon gas inside the vacuum chamber and introducing a reaction gas containing carbon into the vacuum chamber, and a step of introducing a reaction gas containing carbon into the vacuum chamber. Forming a coating layer made of diamond-like carbon on the surface of the second layer by plasma CVD treatment of the reaction gas.

In these methods, a series of a diamond-like carbon coating layer on the sliding surface of the sliding part of the sewing machine is formed together with one or two intermediate layers interposed between the sliding surface and the diamond-like carbon. It is formed collectively by a process.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is an enlarged sectional view of a main part of a sewing machine component used in the sewing machine according to the present invention. The illustrated sewing machine component 1 is made of chromium molybdenum steel (JIS S
A rod-shaped member made of a metal such as CM415) has a surface on which a heat treatment layer 10 is formed by tempering after carburizing and quenching, for example, in order to increase its hardness.

On the surface of the heat treatment layer 10, a coating layer 12 made of diamond-like carbon is applied via an intermediate layer 11. The intermediate layer 11 is provided in order to increase the adhesion strength of the coating layer 12 to the heat treatment layer 10. The intermediate layer 11 shown in FIG. 1 forms the chromium molybdenum steel and the coating layer 12 that constitute the sewing machine component 1. Materials having excellent adhesion to both diamond-like carbons, specifically, silicon (Si), titanium (Ti), tungsten (W), titanium carbide (TiC), silicon carbide (SiC), and chromium carbide ( As a single layer made of any one of CrC), it has a thickness of about 1 μm.

FIG. 2 is an enlarged sectional view of a main part showing another embodiment of a sewing machine component used for the sewing machine according to the present invention. In this figure, a heat treatment layer 10 similar to that in FIG. 1 is formed on the surface of a sewing machine component 1 made of a metal such as chromium molybdenum steel, and a coating layer 12 made of diamond-like carbon is formed on the surface of the heat treatment layer 10. Are applied via an intermediate layer 13 for increasing the adhesion strength between the two.

The intermediate layer 13 shown in FIG. 2 is the same as the intermediate layer shown in FIG.
Unlike the first layer 11, the first layer 1 on the side of the heat treatment layer 10 made of a material mainly composed of chromium (Cr) or titanium (Ti) and having excellent adhesion to chromium molybdenum steel constituting the heat treatment layer 10
3a and a second layer mainly composed of silicon (Si) or germanium (Ge) and made of a material having excellent adhesion to both the constituent material of the first layer 13a and the diamond-like carbon constituting the coating layer 12 13b, the two layers 13a and 13b are each formed to have a thickness of about 0.5 μm.

The coating layer 12 is formed on the surface of the intermediate layer 11 or the intermediate layer 13 with a thickness of about 1 μm. Diamond-like carbon forming such cover layer 12 is a diamond-like thin film, a hard carbon coating, a carbon thin film referred amorphous with hydrogen amorphous carbon film or the _{like, H v = 2000 (kgf /} mm 2) The sewing machine component 1 having the above hardness, excellent wear resistance, extremely low friction coefficient, and self-lubricating property, and having the coating layer 12, is advantageously used on its surface as a sliding surface. be able to.

As will be described in detail later, the coating layer 12 made of diamond-like carbon is provided with a gas containing carbon such as benzene (C ₆ H ₆ ) gas inside a vacuum chamber maintained in a high vacuum state. The reaction gas is turned into a plasma, and the temperature is lowered below the tempering temperature (200 ° C. to 250 ° C.) of the heat treatment layer 10 by a plasma CVD method in which the reaction gas is turned into plasma and adhered to the surface of the target article arranged inside the vacuum chamber. 150 ℃ ~ 200 ℃
The heat treatment layer 10 on the surface of the sewing machine component 1 which can be formed at a low temperature of the order, and can maintain the original surface hardness realized by carburizing, quenching and tempering,
Deterioration of the shape accuracy of the sewing machine component 1 due to the formation of the coating tank 12 can be slightly suppressed, and processing for correcting the shape becomes unnecessary.

The surface roughness of the coating layer 12 formed as described above is lower than the surface roughness of the heat treatment layer 10 on the surface of the sewing machine component 1 serving as a base material, and the surface is used as a sliding surface. In use, local sliding resistance is inevitably added to the surface of the coating layer 12, but diamond-like carbon, which is a constituent material of the coating layer 12, is a hard thin film having self-lubricating properties as described above. Therefore, abrasion generated in the use state of the sewing machine component 1 having the surface as a sliding surface can be slightly suppressed without forcing excessive use of the lubricating oil, and high durability can be obtained.

Further, the coating layer 12 is applied to the heat treatment layer 10 with high adhesion strength by the action of the intermediate layers 11 and 13 interposed between the coating layer 12 and the heat treatment layer 10. Therefore, local deformation of the heat treatment layer 10 due to a load applied to the sliding portion, and peeling of the coating layer 12 due to this deformation can be suppressed slightly.
In the use state of the sewing machine component 1 having the surface of the coating layer 12 as a sliding surface, the occurrence of seizure in the sliding portion can be effectively avoided, and the durability of the sewing machine component 1 is dramatically improved, And stable high-speed operation can be performed.

It should be noted that the configuration of FIG. 1 in which the intermediate layer 11 having a single-layer structure is provided is compared with the configuration of FIG. 2 in which an intermediate layer 13 having a two-layer structure including a first layer 13a and a second layer 13b is provided. Then, the configuration of FIG. 1 has an advantage that the process of forming the covering layer 12 including the intermediate layer 11 is simplified as compared with the configuration of FIG. 2, and the configuration of FIG. As compared with the configuration, there is an advantage that the coating strength of the coating layer 12 can be further increased. That is, in the configuration of FIG. 2, silicon (Si) or germanium (Ge) forming the second layer 13b, together with carbon forming the diamond-like carbon, belongs to Group IVb on the periodic table. Has a coating layer 12 made of diamond-like carbon.
Can be formed with high adhesion strength.

Next, the results of a scratch test performed on a sample formed with a coating layer made of diamond-like carbon to evaluate the mechanical properties (mainly wear resistance) of the coating layer will be described. This test uses a HEIDON-14 type surface physical property tester configured to evaluate the surface physical properties of the coating layer by measuring the resistance generated when the surface is scratched. The test was performed on seed samples, and the respective results were compared.

In each of the samples used for the test, the surface of a chromium molybdenum steel base material used as a sliding part of a sewing machine was polished, and the polished surface was polished with diamond under the following conditions. It is constructed by applying like carbon.

A: A sample in which a coating layer made of diamond-like carbon was directly formed on the surface of a substrate. B: A sample made of diamond-like carbon was formed on the surface of a substrate via a single intermediate layer made of titanium carbide (TiC). Sample having a coating layer formed thereon C: Sample having a coating layer made of diamond-like carbon formed on a surface of a substrate via a single intermediate layer made of silicon carbide (SiC) D: Titanium ( Sample in which a coating layer made of diamond-like carbon was formed via a first layer made of Ti) and a second layer made of silicon (Si) E: A first layer made of titanium (Ti) was formed on the surface of the base material Sample in which a coating layer made of diamond-like carbon is formed via a second layer made of silicon carbide (SiC)

The thickness of the coating layer made of diamond-like carbon in each sample was 1.0 μm.
Each intermediate layer has a thickness of 0.5 μm. The scratch test on these samples was performed using a diamond indenter having a tip angle of 90 ° and a tip radius of curvature of 30 μm, and applying a scratch load in a range of 10 to 500 g under a condition of a scratching speed of 30 mm / min. The test was carried out by changing every 10 g.

FIG. 3 is a diagram showing the results of a scratch test on each of the above samples. The abscissa in this figure indicates the scratch load, and the ordinate indicates the scratch resistance value, and each line in the figure indicates the measured value obtained by performing the above-described test on each of the samples A to E. Are obtained by linear approximation of the points plotted on the graph.

As is apparent from the figure, in each of the samples A to E, a phenomenon in which the scratch resistance rapidly increases when the scratch load reaches a predetermined critical load is shown.
This means that, below the critical load, the indenter of the testing machine is in a state of sliding on the surface of the coating layer, and above the critical load, the indenter is caught by a crack generated on the surface of the coating layer, It is considered that the scratch resistance increased rapidly. Therefore, the inflection point of each line in FIG. 3 is a critical load at which a crack occurs in the coating layer on the surface of each of the samples A to E, and the magnitude of this value indicates whether the adherence of the coating layer to the base material is good or bad. Can be determined.

As shown in FIG. 3, the critical load of the sample A in which the coating layer made of diamond-like carbon was formed directly on the surface of the substrate was 80 g. On the other hand, a coating layer made of diamond-like carbon was formed on the surface of the base material via a single intermediate layer, and the critical loads of Samples B and C corresponding to the embodiment shown in FIG. The weight is 180 g in the case and 220 g in the case of the sample C. Further, a coating layer made of diamond-like carbon is formed on the surface of the base material via two intermediate layers, and the critical loads of Samples D and E corresponding to the embodiment shown in FIG. In the case of 350 g and the sample E, it reaches 380 g. From the above results, it is clear that in the case of the present invention, a diamond-like carbon coating layer can be formed with high adhesion strength.

A coating layer 12 made of diamond-like carbon
Is the intermediate layer 11 or the intermediate layer by a series of procedures shown below.
13 can be formed. FIG. 4 is a cross-sectional view schematically showing a configuration of a sputtering apparatus used for forming the intermediate layer 11 or 13.

As shown, the sputtering apparatus 4 has a gas inlet
A target holder 43 disposed in the vicinity of one side wall, a sample stage 44 disposed in the vicinity of the other side wall and facing the target holder 43, and a target holder. The shutter is provided with a shutter (not shown) that isolates the arrangement portion 43 from other portions. The sample table 44
Is provided on the upper portion thereof so as to secure electrical insulation between the sewing machine component 1 set as described later and the vacuum tank 40.

When the intermediate layer 11 or 13 is formed on the surface of the sewing machine component 1 using such a sputtering apparatus 4, first,
A target 46 made of the material of the intermediate layer 11 or the intermediate layer 13 is attached to a target holder 43 inside the vacuum chamber 40 and connected to a target power source 47. On the other hand, the surface of the target sewing machine component 1 is cleaned and the vacuum chamber 40 is cleaned. Introduced into the target
It is set on the sample stage 44 so as to face 46 and is connected to a DC power supply 48.

Next, the shutter is closed and the inside of the vacuum chamber 40 is evacuated to 3 × 10 ⁻⁵ Torr or less through the exhaust port 42, and then argon gas serving as a sputtering gas is supplied from the gas inlet 41. , And the degree of vacuum inside the vacuum chamber 40 is adjusted to 3 × 10 ⁻³ Torr.

In this state, a DC negative voltage of −50 V is applied to the sewing machine component 1 connected to the DC power supply 48, and −500 to −600 is applied to the target 46 connected to the target power supply 47.
When a DC negative voltage of V is applied, plasma is generated inside the vacuum chamber 40, the argon gas introduced therein is ionized, and the surface of the sewing machine component 1 is ion bombarded to remove an oxide film on the surface. Is done.

Next, the shutter is opened and the target
When the target 46 is exposed, the surface of the target 46 is sputtered by the argon ions in the plasma, and the constituent molecules of the target 46 that have been knocked out from the surface adhere to the surface of the sewing machine component 1 and the surface Target 46
Is formed.

When the intermediate layer 11 is formed as a single layer as shown in FIG. 1, the target 46 is made of silicon (Si), titanium (Ti), tungsten (W),
A single sputtering process using titanium carbide (TiC), silicon carbide (SiC), or chromium carbide (CrC) may be performed.

When the intermediate layer 11 made of titanium carbide or silicon carbide is formed, titanium (Ti) or silicon (Si) is used as the target 46, and sputtering is performed using argon ions, Methane (CH ₄ ) from the gas inlet 41 into the tank 40
A suitable amount of a gas containing carbon, such as a gas, is introduced, and the carbon molecules in the gas and the sputtered titanium or silicon molecules are reacted with each other while reacting to adhere to the surface of the sewing machine component 1 by using titanium carbide or It is also possible to form intermediate layer 11 made of silicon carbide.

As shown in FIG. 2, the first layer 13a and the second layer 13b
When forming the intermediate layer 13 having a two-layer structure comprising
Using a sputtering apparatus 4 having two target holders 43 and 43 separated by separate shutters inside 40,
A target 46 made of chromium or titanium may be set on one target holder 43, and a target 46 made of silicon or germanium may be set on the other target holder 43, and sputtering may be performed on these targets 46, 46 sequentially. .

Since the thickness of the intermediate layer 11 or the intermediate layer 13 formed according to the above procedure corresponds to the length of the sputtering process time, it is necessary to stop each sputtering process when a predetermined thickness is obtained. Thereby, the intermediate layer 11 or the intermediate layer 13 having a desired thickness can be formed.

Next, a procedure for forming the coating layer 12 made of diamond-like carbon on the surface of the intermediate layer 11 or the intermediate layer 13 formed as described above will be described. FIG. 5 is a cross-sectional view schematically showing a configuration of a plasma CVD apparatus used for forming the coating layer 12. As shown in FIG.

As shown in the figure, the plasma CVD apparatus 5 has an upper part inside a vacuum chamber 50 having a gas inlet 51 and an exhaust port 52.
While having an anode 53 and a filament 54, it is provided with a sample stage 55 disposed in the lower part of the inside facing the anode 53.

Using such a plasma CVD apparatus 5,
When forming the coating layer 12 made of diamond-like carbon, the sewing machine component 1 after the step of forming the intermediate layer 11 or the intermediate layer 13 is introduced into the vacuum chamber 50, and the sample table is placed so as to face the anode 53. 55 on the DC power supply 56
Connect to

Next, the inside of the vacuum chamber 50 is evacuated to 3 × 10 ⁻⁵ Torr or less through an exhaust port 52, and then a reaction gas containing carbon, for example,
An appropriate amount of benzene (C ₆ H ₆ ) gas is introduced, and the degree of vacuum inside the vacuum chamber 50 is adjusted to 3 × 10 ⁻³ Torr.

In this state, a DC negative voltage of -3 kV is applied to the sewing machine component 1 connected to the DC power source 56, and a DC voltage of +50 V is applied to the anode 53 connected to the anode power source 57. An AC voltage of about 10 V is applied to the filament 54 connected to the power supply 58 so that a current of 30 A flows. As a result, plasma is generated around the sewing machine component 1 set on the sample table 55 inside the vacuum chamber 50, and carbon contained in the reaction gas is deposited on the surface of the sewing machine component 1 to which the negative voltage has been applied. The coating layer 12 made of diamond-like carbon is deposited through the layer 11 or 13.

The thickness of the coating layer 12 thus formed is
Since the length of the plasma CVD process is as described above, by stopping the process at a predetermined time, the coating layer 12 having a desired thickness can be formed.

In the above description, the intermediate layer 11 or
The sputtering process for forming the layer 13 and the plasma CVD process for forming the coating layer 12 are performed by separate apparatuses (a sputtering apparatus 4 and a plasma CVD apparatus 5). It is performed within the device and can be performed collectively by a common device. In this case, after the step of forming the intermediate layer 11 or 13 is completed, the argon gas in the vacuum chamber may be exhausted, and a reaction gas containing carbon may be introduced.

The reaction gas used in the plasma CVD process for forming the coating layer 12 is not limited to the above-mentioned benzene (C ₆ H ₆ ) gas, but may be methane (CH ₄ ) gas or ethylene (C ₂ H ₄ ) gas. A) Gas containing carbon such as gas, and liquid vapor containing carbon such as hexane (C ₆ H ₁₄ ) can be used.

Further, the plasma C used to form the coating layer 12
The VD device is not limited to the device having the configuration shown in FIG. 5, but various types of devices are in practical use.
It is needless to say that it may be used for the formation of.

FIG. 6 is an explanatory diagram of the operation of a looper bar as an example of a sewing machine component having a sliding surface treated as described above. The illustrated looper bar 2 is a round bar-shaped member that operates the upper looper 20 on the needle plate of the overlock sewing machine. Looper support metal 21 serving as a support member for looper bar 2
Is fixedly installed in a sewing machine bed (not shown), and a looper guide 22 having a columnar shape is rotatably fitted and supported at the tip of the looper support metal 21 while keeping its axis substantially horizontal. ing. The looper guide 22 is provided with a guide hole 23 penetrating in the radial direction, and the looper bar 2 is supported so as to be slidable in the axial length direction with an intermediate portion thereof inserted through the guide hole 23.

An upper looper 20 is attached to the upper end of the looper bar 2 protruding above the sewing machine bed. The lower end of the looper bar 2 located in the sewing machine bed is connected to a looper shaft S via a looper crank 24. It is connected to. Looper shaft S
Is repeatedly rotated within a predetermined angle range by transmission from a lower shaft (not shown), and the looper crank 24
Swings within a predetermined angle range in a plane including its longitudinal direction.

When such a swing occurs, the looper rod 2
When the lower end is pushed up and down, it slides at a high speed in the guide hole 23 of the looper guide 22 and swings with the rolling of the looper guide 22, and the state shown in FIG. 6B is repeated, and the upper looper 20 attached to the upper end of the looper bar 2 moves leftward as shown in FIG. 6A and rightward as shown in FIG. 6B. It repeatedly operates between the retreat position.

A sliding resistance against the inner surface of the guide hole 23 acts on the looper rod 2 performing the above operation, and a bending force acts on the looper rod 2 in accordance with the swing. Wear and seizure are likely to occur at the contact portion. Such wear and seizure is caused by the diamond-like carbon made of diamond-like carbon firmly adhered to the outer surface of the looper rod 2 serving as a sliding surface against the guide hole 23 via the intermediate layers 11 and 13 as described above. By forming the coating layer 12 of the above, it can be effectively prevented, and a stable operation can be performed for a long time. The coating layer 12 may be formed on the inner surface of the guide hole 23.

FIG. 7 is a diagram for explaining the operation of a needle bar as another example of a sewing machine component having a sliding surface treated as described above. As shown in the figure, the needle bar 3 is supported at two locations in the axial direction by bushes 30, 31 fitted and fixed respectively to the upper and lower walls of the sewing machine arm A, and is mounted between these bushes 30, 31. Is connected to an upper shaft (not shown) inside the sewing machine arm A via a known transmission mechanism including a needle bar holder 32, and the upper and lower bushes 30, 31 are used as guides in accordance with the rotation of the upper shaft. It is made to do.

A needle 34 is attached via a needle stopper 33 to the lower end of the needle bar 3 projecting below the sewing machine arm A.
The vertical movement of the needle bar 3 is caused by a relatively long stroke as shown by H in the drawing in order to move the needle 34 up and down.
The inner sliding surface 31 slides, and the sliding speed increases with the speeding up of the sewing machine, causing wear and seizure.

As described above, such abrasion and seizure are caused on the outer surface of the needle bar 3 serving as a sliding surface at a high speed, as described above.
By forming the coating layer 12 made of diamond-like carbon firmly adhered through the layer 13, it can be effectively prevented, and a stable operation can be performed for a long time. The coating layer 12 may be formed on the inner surfaces of the bushes 30, 31.

The diamond-like carbon forming the coating layer 12 is an amorphous carbon thin film having a high hardness, having a very small friction coefficient and a self-lubricating property. By supplying a small amount of lubricating oil, a good lubricating state can be obtained, and the lubricating oil leaks through the fitting gap with the lower bush 31 and alleviates the risk of soiling the fabric being sewn by the needle 34. Can be.

The formation of the coating layer 12 made of diamond-like carbon as described above is not limited to the sliding surfaces of the looper bar 2 and the needle bar 3 described above, and other components that may cause abrasion and seizure may occur. The present invention can be applied to all sewing machine parts having a sliding surface with the above, and it is possible to cope with an increase in operating speed.

[0067]

As described above in detail, in the sewing machine according to the present invention, a coating layer made of diamond-like carbon having a high hardness and a small friction coefficient is formed on the sliding surface of the sliding part with other parts. Therefore, the occurrence of abrasion and seizure in the sliding portion can be effectively prevented, and since the coating layer is applied via the intermediate layer, a strong applied state is obtained and stable for a long time. High-speed operation becomes possible.

Further, since the intermediate layer between the sliding surface and the coating layer is constituted by a single layer made of a material having excellent adhesion to both the sliding surface and the coating layer, the coating including the intermediate layer is included. The layer forming process can be simplified, and sufficient adhesion strength can be realized for the formed coating layer.

Further, the intermediate layer between the sliding surface and the coating layer has a first layer made of a material having excellent adhesion to the sliding surface, and an excellent adhesion to both the first layer and the coating layer. And a second layer made of a material having a good quality, the coating layer can be formed with good adhesion strength, and the occurrence of wear and seizure can be more reliably prevented. it can.

Further, the coating layer made of diamond-like carbon can be formed at a temperature lower than the heat treatment temperature of the surface of the sliding component as the base material, and the surface hardness of the base material does not decrease. The coating layer can be prevented from peeling off due to the deformation of the material, and the occurrence of seizure can be more effectively prevented.

The diamond-like carbon constituting the coating layer is an amorphous carbon thin film and has a self-lubricating property. Therefore, even at high speed, a good amount of lubricating performance can be obtained with a small amount of lubricating oil, and excess lubricating oil can be obtained. The risk of the cloth being sewn being soiled due to the scattering of water is alleviated.

Further, since a coating layer made of diamond-like carbon was formed on the outer surface of the needle bar that slides at a high speed and the looper bar that slides under a high load, the needle bar which is an important part It is possible to effectively prevent the occurrence of wear and seizure on the looper bar, and it is possible to cope with an increase in operating speed.

Further, in the method of manufacturing a sewing machine component according to the present invention, a coating layer made of diamond-like carbon is provided on the sliding surface of the sliding component of the sewing machine together with the intermediate layer interposed between the sliding surface and the sliding surface. The present invention has excellent effects, for example, it can be formed in a lump by the above steps.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a sewing machine component used for a sewing machine according to the present invention.

FIG. 2 is an enlarged sectional view of a main part showing another embodiment of a sewing machine component used for the sewing machine according to the present invention.

FIG. 3 is a diagram showing the results of a scratch test performed on samples formed with a diamond-like carbon coating layer under various conditions.

FIG. 4 is a cross-sectional view schematically showing a configuration of a sputtering apparatus used for forming an intermediate layer.

FIG. 5 is a cross-sectional view schematically illustrating a configuration of a plasma CVD apparatus used for forming a coating layer.

FIG. 6 is an explanatory diagram of an operation of a looper bar as an example of a sewing machine component.

FIG. 7 is an explanatory diagram of an operation of a needle bar as another example of the sewing machine component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sewing machine part 2 Looper bar 3 Needle bar 4 Sputtering device 5 Plasma CVD device 10 Heat treatment layer 11 Intermediate layer 12 Coating layer 13 Intermediate layer 13a First layer 13b Second layer 22 Looper guide 23 Guide hole 30 Bush 31 Bush

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideo Shinomiya 6-11-12 Honcho, Tanashi-shi, Tokyo Citizen Watch Co., Ltd. Inside Tanashi Factory (72) Inventor Akiju Itabashi 6-1-112, Honcho, Tanashi-shi, Tokyo No. Citizen Watch Co., Ltd. Tanashi Factory

Claims (6)

[Claims] 1. A sewing machine provided with a sliding component having a coating layer formed on a sliding surface with another component, wherein the coating layer is formed of diamond-like carbon adhered to the sliding surface via an intermediate layer. A sewing machine characterized by being formed. 2. The sewing machine according to claim 1, wherein the intermediate layer comprises a single layer made of silicon, titanium, tungsten, titanium carbide, silicon carbide or chromium carbide. 3. The intermediate layer has a first layer on the sliding surface side made of a material mainly composed of chromium or titanium, and a second layer on the side of the coating layer mainly composed of silicon or germanium. The sewing machine according to claim 1, further comprising: 4. The sewing machine according to claim 1, wherein the coating layer is formed on outer surfaces of a needle bar and a looper bar. 5. A method for manufacturing a sliding part of a sewing machine in which a coating layer made of diamond-like carbon is formed on a sliding surface with another part. And arranging the inside of the vacuum chamber, and introducing an argon gas into the evacuated vacuum chamber to ionize the silicon, titanium, tungsten, titanium carbide, silicon carbide or chromium carbide. A step of forming an intermediate layer on the sliding surface by sputtering as a target; a step of discharging argon gas inside the vacuum chamber and introducing a reaction gas containing carbon into the vacuum chamber; Forming a coating layer made of diamond-like carbon on the surface of the intermediate layer by plasma CVD processing of the reaction gas introduced into the inside of the tank. Sewing machine parts method of manufacture to be. 6. A method for manufacturing a sliding part of a sewing machine in which a coating layer made of diamond-like carbon is formed on a sliding surface with another part. And a step of evacuating the inside of the vacuum chamber; introducing an argon gas into the evacuated vacuum chamber to ionize it; and performing sputtering using a target of chromium or titanium to form the sliding surface. Forming a second layer on the surface of the first layer by a sputtering process using silicon or germanium as a target, followed by argon in the vacuum chamber. Discharging a gas and introducing a reaction gas containing carbon into the vacuum chamber; turning the reaction gas introduced into the vacuum chamber into plasma; and performing plasma CVD on the second layer. Forming a coating layer made of diamond-like carbon on the surface of the sewing machine.