JP2885118B2 - Sewing machine hook device and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shuttle device for a sewing machine which can be operated at a high speed and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, an outer kettle or a middle kettle of a sewing machine of a sewing machine used for industrial use is made of a metal material such as ordinary carbon steel. And so on. In addition, lubricating oil is supplied through the inside of the drive shaft of the outer hook to the rail groove and the track surface of the outer hook and the inner hook, which are particularly slid by the relative rotation.
Since the outer hook rotates at a speed about twice as high as that of the main shaft of the sewing machine, it generates heat due to friction, and there is a risk of causing seizure when the continuous operation is performed for a long time. In order to prevent such seizure, for example, Japanese Utility Model Publication No. Hei 3-6293 proposes a technique for improving the seizure resistance by performing a nitrocarburizing treatment on an outer pot.

[0003]

However, according to the conventional sewing machine of the sewing machine, the surface of the sewing machine is hardened by nitrocarburizing.
A nitride film layer having a thickness of about 10 μm to 10 μm is formed. At this time, remarkable thermal deformation occurs due to being placed in a high-temperature atmosphere of 500 to 600 ° C. during soft nitriding. Therefore, the roundness of the outer groove of the outer hook is also lost, and the dimension control becomes difficult.Therefore, the gap between the outer groove of the outer hook and the rail band of the inner pot must be set to be large in advance. No. However, if the gap is widened, there is a problem that noise due to rattling between the rail groove of the outer hook and the rail belt of the inner hook during high-speed operation increases.

[0004] However, the present invention has been made to solve the above-mentioned problems, and a predetermined dimensional control can be easily performed by lowering the ambient temperature of the nitriding treatment as much as possible to eliminate the thermal deformation of the pot to be treated. It is another object of the present invention to provide a shuttle device of a sewing machine and a method of manufacturing the same, which can reduce the noise of the shuttle device by minimizing a gap between the outer shuttle and the inner shuttle, particularly at a sliding portion.

[0005]

In order to achieve the above object, a shuttle device according to the present invention is provided in a shuttle device of a sewing machine in which an inner shuttle rotatable relative to the outer shuttle is disposed inside the outer shuttle.
At least one portion of at least one of the outer kettle and the inner kettle, which is in sliding contact with the rotator, is subjected to a fluoridation treatment, and further a nitriding treatment is applied to the portion to form a nitride film.

It is preferable that the nitride film is formed on at least a portion of one of the outer kettle and the inner kettle that is in sliding contact with the other, and hard chrome plating is applied on at least a portion of the other kettle that is in sliding contact with the other. .

Further, it is preferable that carburizing and quenching and tempering are performed on the portion where the nitride film is to be formed prior to the fluoridation.

Further, at least a portion of at least one of the outer kettle and the inner kettle rotatably disposed inside the outer kettle, which is in sliding contact with the at least one kettle, is heated for a predetermined time in a fluorine-based gas atmosphere. Forming a fluoride film on the surface of the portion, and then heating the portion in a nitriding gas atmosphere for a predetermined time to separate and remove the fluoride film, and at the same time, replace the nitride film with the removed portion. By doing so, a shuttle device is obtained.

[0009]

According to the sewing machine hook device of the present invention having the above-described structure, at least a portion of at least one of the outer hook and the inner hook that is in sliding contact with the rotary hook is subjected to fluorination treatment, and furthermore, the portion is nitrided. Processing is performed to form a nitride film. Accordingly, the temperature of the heat treatment during the nitriding treatment can be reduced as much as possible to prevent the dimensions between the outer kettle and the inner kettle from being distorted due to thermal deformation, and the noise of the kettle device can be reduced.

Then, the nitride film is formed on at least a portion of one of the outer kettle and the inner kettle which is in sliding contact with the other, and hard chrome plating is applied to at least a portion of the other kettle which is in sliding contact with the rotary. In this case, the wear resistance of the other kettle on which the hard chrome plating has been performed can be improved, and the sliding property of the portion of the outer hook and the inner hook that is in sliding contact with the rotation can be further improved.

Further, the portion where the nitride film is formed is subjected to carburizing and quenching and tempering prior to the fluoridation process, so that the portion where the nitride film is formed has a higher hardness over its deep portion. can do.

Further, at least a portion of at least one of the outer kettle and the inner kettle rotatably disposed inside the outer kettle, which is in sliding contact with the at least one kettle, is heated in a fluorine-based gas atmosphere for a predetermined time. Forming a fluoride film on the surface of the portion, and then heating the portion in a nitriding gas atmosphere for a predetermined time to separate and remove the fluoride film, and at the same time, replace the nitride film with the removed portion. By doing so, a shuttle device is manufactured. In this case, by performing the fluoridation treatment, a fluoride film is formed in place of the oxide film, and this fluoride film has a function of protecting the surface of the workpiece as a stable film at a fluorination treatment temperature or lower. Have. Thereafter, when the temperature of the nitriding gas atmosphere is increased to perform the nitriding treatment, the fluoride film acts as an activation film on the contrary, and this activation effect makes nitrogen much easier than before. And then penetrates into the surface layer of the workpiece. Therefore, the temperature of the nitriding treatment can be lowered from about 600 ° C., which is usually about 600 ° C., to about 400 ° C. or less, and thermal deformation of the outer pot or the inner pot can be almost eliminated. In this nitriding step,
An increase in dimension due to the formation of the nitride film can be suppressed to about 1 to 2 μm, and a change in surface roughness can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a horizontal full rotary hook of the present embodiment, and FIG. 2 is an enlarged cross-sectional view near the sliding surfaces of an outer hook 1 and a middle hook 3. The outer shuttle 1 has a shaft 2 formed on a lower surface thereof, and is rotatably driven around an axis extending in a vertical direction. Inside the outer hook 1, an inner hook 3 is inserted and arranged so as to be relatively rotatable in a horizontal plane, and is held by an inner hook retainer 4 so as not to escape upward. The rail band 7 provided on the outer peripheral surface of the inner hook 3 is fitted to the rail groove 8 provided on the inner peripheral surface of the outer hook 1 with a suitable gap so as to be slidable. The relative rotation of the outer hook 1 with respect to the inner hook 3 is allowed. On the outer periphery of the outer hook 1, a point 5 for catching the upper thread is formed.
The intermediate hook 3 is formed with a rotation stopping projection 6 which is inserted between a pair of regulating surfaces provided at a minute interval on the sewing machine bed and regulates the rotation of the intermediate shuttle 3 within a minute range. Have been.

Next, a description will be given of a method of manufacturing the shuttle device configured as described above. The outer pot 1 is formed by forging or cutting using carbon steel, chromium molybdenum steel, or the like as a base material. As a first step, the outer kettle 1 is heated in a fluorine-based gas atmosphere for a predetermined time.
Then, as a second step, the outer vessel 1 is heated in a nitriding gas atmosphere for a predetermined time to separate and remove the fluoride film, and at the same time, a nitride film is formed on the trace of the removal. 9 is substituted.

The contents of the manufacturing method and the chemical substances to be handled will be described in more detail. The following are used as the fluorine-based gas when forming the fluoride film.
NF ₃ , BF ₃ , CF ₄ , HF, SF ₆ , F ₂ , CH ₂ F ₂ ,
At least one fluorine source component selected from CH ₃ F, C ₂ F ₆ , WF ₆ , CHF ₃ , SIF _{4 and the} like is contained in an inert gas such as N ₂ . Among these, NF ₃ is the most excellent in terms of reactivity, handleability and the like.
When NF ₃ is used, when the temperature of the furnace containing the outer kettle 1 and NF ₃ is heated to about 250 ° C. to 400 ° C., the NF ₃ generates fluorine as an active group, and this fluorine is By reacting with the first metal, a very thin fluoride film is formed on the surface. This fluoride film functions as a protective film until the next step of nitriding, and functions as an active film that actively introduces nitrogen into the surface layer at a relatively low temperature during the nitriding.

When the outer vessel 1 on which the fluoride film is formed is heated at a temperature of about 400 ° C., which is about 200 ° C. lower than the conventional temperature, in a known nitriding gas, for example, ammonia gas, At the same time as the fluoride film is separated and removed, N atoms are adsorbed by the outer vessel 1 and penetrate and diffuse into the metal. As a result, the nitrided hard film 9 containing nitride is formed on the surface of the outer vessel 1.
Is formed in place of the fluoride film.

The nitride film 9 thus formed has excellent seizure resistance, abrasion resistance and impact resistance unchanged from the conventional one. If the outer pot 1 is carburized and quenched and tempered before the nitriding process, the outer pot 1 can have a higher hardness from the surface to the deep portion.

On the other hand, in the present embodiment, the inner pot 3
Using a steel material similar to that of the outer pot 1 as a base material, at least the track band 7 is formed with a hard chromium-plated layer 10 in order to improve wear resistance and slipperiness. The hard chrome plating of the inner hook 3 may be replaced with another wear-resistant treatment.

In the above, while the outer pot 1 is subjected to the nitriding treatment and the inner pot 3 is subjected to hard chrome plating, the surface treatment of the outer pot 1 and the inner pot 3 may be reversed. Alternatively, even if both the outer pot 1 and the inner pot 3 are subjected to the nitriding treatment of the above step, excellent sliding characteristics are maintained.

As described above, by performing the fluorination treatment in advance and then performing the nitridation treatment, the nitridation treatment can be carried out at a low temperature of about 400 ° C., which is lower than the normal about 600 ° C. to about 200 ° C. Since the enlargement of the pot size and thermal deformation can be suppressed as much as possible, and the surface roughness due to the treatment is hardly observed, the track groove 8 of the outer pot 1 which had to be 50 to 80 μm in the conventional nitrocarburized product was required. The gap between the track belts 7 of the inner pot 3 can be reduced to 10 to 20 μm.

In the present embodiment, the nitride film 9 is formed on the entire outer pot 1 or the inner pot 3. However, the nitride film 9 is formed only on the rail groove 8 of the outer pot 1 or the rail band 7 of the inner pot 3. You may make it. In this case, it is necessary to mask a portion other than the rail groove 8 or the rail band 7. In this embodiment, the horizontal full rotary hook has been described. However, it goes without saying that the present invention can be applied to a vertical full rotary hook.

[0023]

As is apparent from the above description, according to the sewing machine of the sewing machine of the present invention, the temperature of the atmosphere for nitriding can be reduced as much as possible, and the thermal deformation and the dimensional change of the to-be-processed can be almost eliminated. Therefore, it is possible to easily perform the dimensional control of the outer pot and the inner pot. In addition, the gap between the outer hook and the inner hook can be reduced as much as possible to reduce the noise of the hook during high-speed operation.

[Brief description of the drawings]

FIG. 1 is a side view of a shuttle device according to an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a state in which a rail band of a middle hook is fitted into a rail groove of an outer hook.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer pot 3 Middle pot 7 Rail band 8 Rail groove 9 Nitride film

Claims (4)

(57) [Claims] 1. A shuttle device of a sewing machine in which an inner shuttle rotatable relative to the outer shuttle is disposed inside the outer shuttle, wherein at least one of the outer shuttle and the inner shuttle has a portion that is in sliding contact with at least one of the shuttles. A sewing machine for a sewing machine, characterized in that a chemical conversion treatment is performed, and further a nitriding treatment is performed on the portion to form a nitride film. 2. The method according to claim 2, wherein the nitride film is formed on at least a portion of one of the outer kettle and the inner kettle that is in sliding contact with the other, and hard chrome plating is applied on at least a portion of the other kettle that is in sliding contact with the other. The shuttle device of the sewing machine according to claim 1, wherein: 3. The shuttle apparatus according to claim 1, wherein a portion where the nitride film is formed is carburized and quenched and tempered prior to the fluorination treatment. 4. At least a portion of at least one of the outer kettle and the inner kettle rotatably disposed inside the outer kettle, which is in sliding contact with the at least one kettle, is heated for a predetermined time in a fluorine-based gas atmosphere. Forming a fluoride film on the surface of the portion, and then heating the portion in a nitriding gas atmosphere for a predetermined time to separate and remove the fluoride film, and at the same time, replace the nitride film with the removed portion. A method for manufacturing a shuttle device of a sewing machine, comprising: