JPH114987A - Shuttle for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a shuttle unlubricatedly usable for a long time, by covering the surface of one of a guide groove of the rotating hook or a guide protrusion of the rotating hook bobbin case holder by a composite layer which is made by dispersing fluororesin into nickel-phosphorous and forming the other surface to be slid thereon by synthetic resin. SOLUTION: Both a rotating hook 5 and a rotating hook bobbin case holder 16 are constituted of a carburization quenched and tempered steel material. A cover layer of nickel-phosphorus-polytetrafluoro-ethylene is formed on the surfaces of the rotating hook 5 including a guide groove 14 and on the rotating hook bobbin case holder not including a protrusion 17. The nickel-phosphorus- polytetrafluoroethylen cover layer is made by dispersing fluororesin particles such as polytetrafluoroethylen particles in an electroless plating bath comprising nickel-phosphorus and heat treating to form a composite layer. The guide protrusion 17 of the rotating hook bobbin case holder is formed of synthetic resin such as polyamide resin. Thus the abrasion amount and the friction coefficient of the shuttle can be kept for a long time even under an unlubricated condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine which supports an outer shuttle at an end of a lower shaft, and which can hold an inner shuttle containing a bobbin inside the outer shuttle even during rotation of the outer shuttle. More particularly, the present invention relates to a sewing machine hook suitable for use in an industrial sewing machine having a high rotation speed.

[0002]

2. Description of the Related Art In the above-mentioned industrial sewing machine, the needle reciprocates approximately 5,500 times per minute at a maximum.
It will rotate about 1000 times. Therefore, unless lubricating oil is forcibly supplied by a pump to the bearings of the respective parts rotating at such a high speed, the parts may be overheated and seized or worn.

[0003] By the way, a shuttle in a sewing machine is generally
Because the lower thread is hooked on the upper thread through which the needle is inserted, the inner hook that houses the bobbin wound with the lower thread is stationary despite the reciprocation of the needle. On the other hand, the outer hook provided with the hook for hooking the upper thread rotates at a high speed in association with the reciprocation of the needle. At this time, the guide groove formed in the outer hook is rotated by being guided by the guide projection formed in the inner hook. Therefore, during high-speed operation of the sewing machine, seizure may occur due to frictional resistance generated on the contact surface between the inner hook and the outer hook,
In addition, the frictional resistance causes a large resistance at the hook stopper, which may make it difficult to separate the upper thread during the formation of the stitch, or may cause the thread to break.

Therefore, it is necessary to reduce the sliding resistance of the sliding surface of the inner hook, which slides relatively with the outer hook. The lubricating oil passage formed in the inner kettle is supplied to the race surface of the inner kettle through another lubricating oil passage formed in the outer kettle.

First, such a conventional sewing machine hook is shown in FIG.
3 will be described.

In FIG. 13, there is provided a lower shaft 1 which can be rotated at a high speed by a driving means such as a motor (not shown). The lower shaft 1 is provided at an interval in the axial direction.
A thrust receiver 3 incorporated in a pair of metals 2 (only one is shown) is supported so as to restrict axial movement.
A first lubricating oil passage 4 extending in the axial direction is formed in the center of the lower shaft 1, and a base end side of the lower shaft 1 (not shown) is formed in the first lubricating oil passage 4. Can be supplied with lubricating oil.

An outer shuttle 5 is fixed to the tip of the lower shaft 1. The outer hook 5 has a disk-shaped base 6 fitted on the outer periphery of the distal end of the lower shaft 1 and a substantially cylindrical outer hook main body 10 connected to the distal end of the base 6. ing. The base 6 has a center hole 7 into which the tip of the lower shaft 1 can be inserted relatively densely. The base 6 is formed with a radial screw hole 8 communicating with the center hole 7 from an outer peripheral surface 6a thereof.
And the tip of the screw 9 is pressed against the outer peripheral surface 1a of the lower shaft 1 so that the outer hook 5 can rotate integrally with the lower shaft 1.

[0008] The outer hook main body 10 is provided with a substrate 11 having a diameter larger than that of the base 6 and protruding concentrically from the tip of the base 6.
It is formed of a substantially cylindrical outer peripheral wall 12 continuously provided on the front end side of the substrate 11. A relatively thin hook member 13 is attached to an outer peripheral surface 12a of the outer peripheral wall 12 with a screw (not shown). Further, the outer pot 5
An annular guide groove 14 is formed on the inner peripheral surface of the outer peripheral wall 12.

In the inner space 15 of the outer hook 5, an inner hook 16 rotatable relative to the outer hook 5 is provided.
The inner shuttle 16 is formed in a substantially cylindrical shape as a whole, and is fitted into the guide groove 14 of the outer shuttle 5 on the outer peripheral surface 16a of the inner shuttle 16 and relatively in the circumferential direction. A substantially annular guide protrusion 17 slidable around is provided except for a portion through which the thread comes off. The outer peripheral surface of the guide projection 17 is called a race surface. A support plate 18 extending in the diametrical direction is integrally attached to a base end of the inner pot 16. A central portion of the support plate 18 in the longitudinal direction is provided in the axial direction of the inner pot 16. Are protruded coaxially. A bobbin (not shown) around which a bobbin thread is wound is mounted on the support pin 19.

A circular recess 20 communicating with the center hole 7 and having a larger diameter than the center hole 7 is formed in the substrate 11 of the outer hook body 10 of the outer hook 5. A second lubricating oil passage 21 extending inside the shuttle 5 is communicated with. The second lubricating oil passage 21 is formed in the substrate 11 so as to extend substantially in the radial direction, and communicates with the radial passage 22 communicating with the circular recess 20 and the outer end of the radial passage 22. And an axial passage 23 extending substantially in the axial direction from the substrate 11 to the outer peripheral wall 12.

The distal end of the axial passage 23 reaches the vicinity of the guide groove 14, and the outer peripheral wall 12 at this point communicates with the guide groove 14 and the axial passage 23, respectively. A circular filtration chamber 24 is formed. The filtration chamber 24 is open to the outer peripheral surface 12a of the outer peripheral wall 12, and is opened and closed by a cover (not shown). Further, in the filtration chamber 24, a kettle tip filtration member 25 in which fibers made of felt or the like are solidified like a nonwoven fabric is stored.

On the other hand, a holding sleeve 27 for holding an oil amount limiting filter member 26 for limiting the oil amount is mounted on the tip of the lower shaft 1. The holding sleeve 27 has a sleeve body formed on the outer peripheral surface thereof with a threaded portion screwed to a threaded portion (not shown) formed on the inner peripheral surface forming the first lubricating oil passage 4 of the lower shaft 1. And a flange 29 connected to the sleeve main body 28 and having a diameter larger than that of the first lubricating oil passage 4.
The inside of the sleeve body 28 and the circular recess 20
And a communication hole 30 that communicates with. The three
At the inner end of the valve body 28, there is formed a recess 31 which communicates with the communication hole 30 and has a small diameter truncated cone on the communication hole 30 side. The oil amount limiting filter member 26 mounted in the sleeve main body 28 solidifies the fiber made of the above-described felt or the like like a nonwoven fabric, and
Are formed in a columnar shape substantially equal to the inner diameter of the column.

Next, the operation of the conventional sewing machine hook having the above-described configuration will be described.

While the lower shaft 1 rotates at a high speed together with the outer hook 5 and sewing is performed by a needle (not shown), high-pressure lubricating oil is supplied to the first lubricating oil passage 4 of the lower shaft 1 by a pump (not shown). It is supplied by.

By the way, the high pressure lubricating oil is
If the oil is sprayed from the guide groove 14, the cloth or the like being sewn will be contaminated with lubricating oil, but an oil amount limiting filter member 26 is provided in the first lubricating oil passage 4, Due to the resistance of the lubricating oil when it passes through the amount limiting filter member 26, the oil pressure and the oil amount of the lubricating oil are reduced.
Then, a certain amount of lubricating oil is accelerated by centrifugal force when passing through the radial passage 22 of the outer kettle body 10 rotating at high speed, and an appropriate amount of lubricating oil is supplied from the guide groove 14 of the outer kettle 5 to the inner kettle. It will be supplied to 16 guide projections 17.

[0016]

However, in the conventional sewing machine hook, foreign matters such as cloth waste of sewing products and various kinds of abrasion powder are contained in the lubricating oil circulated to reduce the frictional resistance of each sliding portion. May be mixed. Since these foreign substances are filtered by the oil amount limiting filter member 26, if the oil amount limiting filter member 26 is continuously used for a long period of time, the oil amount limiting filter member 26 will be clogged, and the lubricating oil will It will not be supplied to the 16 guide projections 17. For this reason, the outer pot 5 and the inner pot 16
May generate heat, seize, or wear to cause shaking.

The present invention has been made in view of the above problems, and reduces frictional resistance generated on the contact surface between the inner and outer kettles without lubrication, prevents seizure, and is beautiful for a long time. It is an object of the present invention to provide a sewing machine hook capable of maintaining a sewing state.

[0018]

According to a first aspect of the present invention, there is provided a sewing machine hook according to the present invention, wherein a surface of one of a guide groove of an outer hook and a guide projection of an inner hook is provided. This is characterized in that a composite layer in which a fluororesin is dispersed in a coating layer made of nickel-phosphorus is formed, and the other sliding contact portion in sliding contact with the composite layer is formed of a synthetic resin. And, by adopting such a configuration, even under no lubrication, the amount of wear and the coefficient of friction on the sliding contact surfaces of the guide grooves and the guide projections can be suppressed to a small value. A beautiful sewing state can be maintained.

[0019] In the second aspect of the present invention, the outer hook and the inner hook are made of a heat-treated steel material, stainless steel or an aluminum alloy. In that it is formed as a material. And, by adopting such a configuration, the amount of wear and the coefficient of friction can be suppressed to a small value without lubrication even with a sewing machine hook that is formed using a general metal material as a base material. State can be maintained.

A third feature of the sewing machine hook of the present invention resides in that, in the first or second aspect, a polyimide resin or an oil-containing polyimide resin is used as the synthetic resin. By adopting such a configuration, the amount of wear and the coefficient of friction can be reliably suppressed under no lubrication, and a high quality sewing state can be maintained.

[0021]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIGS.

The same or corresponding components as those of the conventional sewing machine of the sewing machine of the present invention are designated by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 shows a guide groove 14 of an outer shuttle 5 and a guide projection 1 of an inner shuttle according to a first embodiment of the shuttle of the present invention.
7 is an enlarged view showing the configuration of FIG. The outer pot 5 and the inner pot 16 are both made of a steel material 32 that has been heat-treated by carburizing, quenching and tempering, and a coating layer 33 of nickel-phosphorus-polytetrafluoroethylene is formed on the surface thereof. Have been. The nickel-phosphorus-polytetrafluoroethylene coating layer 33 is formed by dispersing 5 to 30% by volume of fluororesin particles such as PTFE particles in an electroless plating bath made of nickel-phosphorus, and then heating at about 300 ° C. It is formed into a composite layer by performing a treatment.

The fluororesin particles are not limited to PTFE particles, but may be ETFE (ethylene tetrafluoride resin) particles or FEP (tetrafluoroethylene-hexafluoropropylene).

Further, the guide projections 17 of the inner hook 16 are provided.
Is formed of a synthetic resin such as a polyimide resin. This synthetic resin does not need to be limited to the polyimide resin 34, but the polyimide resin 34 has excellent heat resistance and is suitable for use in a portion that is heated to a high temperature by friction.
In the following description, the polyimide resin 34 will be described as a typical example of a synthetic resin.

The polyimide resin 34 may contain a reinforcing material. As this reinforcing material, at least one selected from carbon fiber, glass fiber, potassium titanate fiber, ceramic fiber, metal fiber, silicon carbide fiber, rock wool fiber and aramid fiber is selected and contained.

Further, if necessary, the polyimide resin 34 may be made of a fluorine resin, graphite, calcium carbonate, mica, glass beads, molybdenum disulfide, clay, silica, alumina, talc, diatomaceous earth, hydrated alumina, shirasu balloon And other fillers, lubricants, release agents, stabilizers, coloring agents, nucleating agents, and other non-crystalline resins (eg, polyethersulfone, polyimide, polyetherimide, polysulfone, polycarbonate, polyarylate, etc.) , Other crystalline resins (eg, polyphenylene sulfide, polyether nitrile, nylon, polyether ketone, polyether ether ketone, polyether ketone ether ether ketone, polyether ether ketone ketone, etc.), liquid crystal polymers and thermosetting resins ( For example, Epoki Resin, polyimide resin, silicone resin, polyamideimide resin, poly benzoyl imidazole resin) may be used in combination.

Further, in order to further enhance the lubricating property and reduce the frictional resistance, the polyimide resin 34 may contain oil such as silicone oil, perfluoroether oil, phenyl ether oil or the like.

The polyimide resin 34 is about 2
It is crystallized by heat treatment at a temperature of 50 ° C. to 350 ° C., and exhibits the performance of the crystalline polymer.

Next, in order to measure a wear amount and a friction coefficient when the guide groove 14 of the outer hook 5 and the guide projection 17 of the inner hook 16 in the first embodiment of the present invention are slid, the wear friction is measured. The test was performed.

FIG. 2 is a schematic diagram showing a high-speed wear friction tester 35 used for measurement of wear friction characteristics. In this high-speed wear friction tester 35, a test piece is
The shaft member 37 is rotated while a predetermined load is applied to the bearing member 36 by the load member 38.
The bearing member 36 is provided with a torque detecting gauge 39 on the side opposite to the load direction, and the friction force is measured by the torque detecting gauge 39.
When a large torque is generated due to seizure or the like between the shaft member 37 and the shaft member 37, the torque detecting gauge 39 is broken. The experimental conditions were as follows.
7 was rotated without lubrication, and the rotation speed of the shaft 37 was set at a speed corresponding to the maximum rotation speed of the sewing machine.

Table 1 shows various combinations of the shaft member 37 and the bearing member 36 used in this test.

[0033] The shaft member 37 as each test piece corresponds to the guide groove 14 of the outer hook 5 in the sewing machine, and the bearing member 36 of the test piece corresponds to the guide projection 17 of the inner hook 16 in the sewing machine.

First, the test piece L1 is made of the steel material 32 which has only been subjected to the heat treatment of carburizing, quenching and tempering for both the shaft member 37 and the bearing member 36 and has not been subjected to any surface treatment. It is a material used for the conventional general outer pot 5 and inner pot 16.

The test piece L2 is made of a steel material 32 on which a nickel-phosphorus-polytetrafluoroethylene coating layer 33 is formed after carburizing, quenching and tempering the shaft member 37 and the bearing member 36. is there.

The test piece L3 is made of a steel material 32 obtained by simply performing a carburizing, quenching and tempering process on a shaft member 37,
The bearing member 36 is made of a polyimide resin 34.

The test piece L4 is made of a steel material 32 obtained by subjecting a shaft member 37 to a carburizing, quenching and tempering treatment and then applying a nickel-phosphorus-polytetrafluoroethylene coating layer 33, and a bearing member 36 for a polyimide resin 34. And corresponds to the material forming the outer hook 5 and the inner hook 16 in the first embodiment.

The test piece L5 is made of a steel material 32 in which a shaft material 37 is carburized, quenched and tempered and then a nickel-phosphorus-polytetrafluoroethylene coating layer 33 is provided, and a bearing material 36 is a polyimide resin 34. This also corresponds to the material constituting the outer pot 5 and the inner pot 16 in the first embodiment.

FIG. 3 and FIG. 4 show the results of tests on these test pieces by the high-speed wear friction tester 35.

FIG. 3 shows the relationship between the time during which the shaft member 37 is rotated and the clearance between the bearing member 36 and the shaft member 37, and the degree of wear can be known. On the other hand, FIG. 4 shows the relationship between the time when the shaft member 37 is rotated and the coefficient of friction between the bearing member 36 and the shaft member 37.

As can be seen from these figures, the test piece L1 made of the same material as the conventional kettle, the clearance increased rapidly and linearly in a short period of time, and reached a value of about 0.4 mm after about 50 hours of rotation. . Further, the coefficient of friction also increased to 0.25, and most of the test pieces L1 were seized and became in a state where the experiment could not be continued.

The test piece L2 has a small increase in clearance at the beginning of the rotation of the shaft 37, is about 0.07 mm after 100 hours, and has a friction coefficient of about 0. It was about 12,
After that, the temperature rapidly increased, and after 200 hours, seizure occurred and the experiment could not be continued. This is considered to be because the nickel-phosphorus-polytetrafluoroethylene coating layer 33 applied to the shaft member 37 and the bearing member 36 was worn out and disappeared when the rotation time elapsed from 50 to 100 hours. .

In the case of the test piece L3, the clearance increased almost in proportion to the increase in the rotation time of the shaft 37, but tended to increase more slowly than the test pieces L1 and L2. . On the other hand, the friction coefficient showed a tendency to stabilize between about 0.17 and 0.19 with the passage of the rotation time, but showed a large value in the initial stage of the test piece 2 as compared with the friction coefficient. . However, since the material of the bearing member 36 is the polyimide resin 34 having high heat resistance, welding and seizure of the resin did not occur.

The test piece 4 is made of the same material as that of the first embodiment. In this case, the clearance increases with the rotation time, but the value is small.
Even after the elapse of time, it could be suppressed to about 0.29 mm. The coefficient of friction was stable throughout, showing a value in the range of about 0.11 to 0.13. For this reason, by forming the nickel-phosphorus-polytetrafluoroethylene coating layer 33 on the surface of the steel material 32 and selecting the polyimide resin 34 as the mating side to be in sliding contact with the nickel-phosphorus-polytetrafluoroethylene coating layer 33, the advantages of the wear and friction characteristics possessed by both are sufficiently exhibited. It is thought that it was able to be done.

Further, since the test piece L5 uses the oil-impregnated polyimide resin 34, the effect of the test piece L4 can be further enhanced. That is, the clearance gradually increases with the rotation time, and after 500 hours, the amount of wear can be further suppressed to about 0.25, and the friction coefficient is about 0.09-0. It could be stabilized within the range of 11 and a smaller value.

As can be seen from the above results, the first embodiment of the present invention can significantly reduce the amount of wear and the friction coefficient over a long period of time even in a non-lubricated state, compared to a conventional sewing machine hook. It is highly likely.

Next, results of a sewing test performed on the first embodiment of the present invention will be described.

In the sewing test method, the sewing machine is driven while rotating the shuttle of the sewing machine in a non-lubricated state, and the sewing is performed in a non-lubricated state at predetermined time intervals. The number of occurrences was measured.

FIG. 5 shows the result of the sewing test on the conventional sewing machine hook, and FIG. 6 shows the result of the sewing test of the first embodiment of the present invention. The abscissas in these figures show the elapsed time during which the idle running operation was performed without lubrication, and the ordinates show the occurrence of seam failure and thread breakage when a sewing test was performed after a certain idle running time. Shows the number of times

As shown in FIG. 5, in the conventional sewing machine hook, when the idle running time without lubrication is 0 hour, the seam defect occurs twice and the thread break occurs four times. It was possible. However, when a sewing test was performed after the idle running operation was performed for 50 hours, thread breakage occurred frequently, and it was impossible to form a seam.

On the other hand, as shown in FIG. 6, according to the first embodiment of the present invention, when the idle running time without lubrication is 0 hour, thread breakage does not occur, and the seam defect is reduced. This occurred only twice, and there was no problem in sewing. This state is 5
The same is true even after the idle running for 0 hours, and it was possible to perform sufficiently satisfactory sewing. Furthermore, even after the idle running operation was performed for 500 hours, thread breakage occurred twice and seam failure occurred only four times, and there was no problem in forming the entire seam.

It is considered that such a difference between the test results is caused by a difference in clearance between the guide groove 14 of the outer hook 5 and the guide projection 17 of the inner hook 16. That is, FIG.
4 is a diagram showing a comparison between a conventional sewing machine hook and the first embodiment of the present invention in terms of clearance with respect to elapsed running time under no lubrication conditions. According to FIG. 7, the clearance between the guide groove 14 and the guide protrusion 17 of the conventional shuttle of the sewing machine is so large that it has already deviated from the standard value after the idling operation for about 30 hours. In the first embodiment, even after the idling operation for 500 hours, it is within the standard value range, and it can be seen that the wear characteristics are extremely good. For this reason, when the sewing is performed according to the first embodiment of the present invention, the play between the outer hook and the inner hook can be suppressed to be small, so that it is possible to suppress the thread breakage and the seam failure even without lubrication. It is considered possible.

From the results of the above-described sewing test, the first of the present invention
In the embodiment, it is possible to perform good sewing for a long period of time even under a non-lubricating state.

In the first embodiment of the present invention,
Although the guide projections 17 are formed on the nickel-phosphorus-polytetrafluoroethylene coating layer 33, they are formed directly on the heat-treated steel material 32 without the coating layer 33 as shown in FIG. You may. FIG.
As shown in FIG. 7, the entire inner pot 16 may be formed of a polyimide resin 34 instead of the steel material 32.
Even in these cases, the portion where the guide groove 14 of the outer shuttle 5 and the guide projection 17 of the inner shuttle 16 are in sliding contact is nickel-
Because of the phosphorus-polytetrafluoroethylene coating layer 33 and the polyimide resin 34, the effect of the friction property between the two is maintained, and the effect under the above-described oil-free condition can be sufficiently obtained.

Therefore, according to the first embodiment of the present invention, the nickel-phosphorus-polytetrafluoroethylene coating layer 33 formed in the guide groove 14 of the outer pot 5 and the polyimide resin 34 serving as the guide projection 17 of the inner pot 16 are formed. However, even if it is slid under oil-free conditions, seizure between the two can be prevented and the amount of wear and the coefficient of friction can both be reduced, so that good sewing can be maintained for a long period of time. it can.

Next, a second embodiment of the sewing machine hook of the present invention will be described.

FIG. 10 shows an outer shuttle 5 according to the second embodiment.
FIG. 3 is an enlarged view showing a configuration of a guide groove 14 and a guide projection 17 of an inner shuttle 16. In the outer pot 5, a polyimide resin 34 is fitted into a portion of the guide groove 14 with respect to a steel material 32 which has been subjected to a heat treatment of carburizing, quenching and tempering, and a nickel-phosphorus-polytetrafluoroethylene coating is formed on other surfaces. A layer 33 is formed. On the other hand, in the inner pot 16, a nickel-phosphorus-polytetrafluoroethylene coating layer 33 is formed on the surface of a steel material 32 that has been subjected to heat treatment of carburizing, quenching and tempering.

Accordingly, according to the second embodiment of the present invention, the polyimide resin 34 fitted in the guide groove 14 of the outer hook 5 and the nickel-phosphorus-polytetra Fluoroethylene coating layer 33
However, even if it is slid under oil-free conditions, it has excellent wear friction characteristics under oil-free conditions and is compatible with the two. Can be reduced, and good sewing can be maintained for a long period of time.

The surface other than the guide groove 14 of the outer hook 5 in the second embodiment shown in FIG.
Although the phosphorus-polytetrafluoroethylene coating layer 33 is formed, as shown in FIG. 11, it is not always necessary to form this coating layer 33, and conversely, as shown in FIG. A nickel-phosphorus-polytetrafluoroethylene coating layer 33 may be formed on the whole, and then a polyimide resin 34 may be fitted only into the guide groove 14. Even in these cases, the effects of the above-described second embodiment can be sufficiently exhibited.

The present invention is not limited to the above embodiments, but can be variously modified as needed.

For example, by using a polyether ether ketone resin or a polyphenylene sulfide resin in addition to the polyimide resin 34, it is possible to obtain the same effect as when the polyimide resin 34 is used.

The base material of the outer pot 5 and the inner pot 16 uses a heat-treated steel material 32.
However, the present invention is not limited to this. For example, stainless steel may be used, or an aluminum alloy characterized by its light weight may be used. When this aluminum alloy is used, the effect of reducing the amount of wear and the coefficient of friction is obtained because the inertial force is reduced.

[0063]

As described above, according to the sewing machine hook of the present invention, the frictional resistance generated on the contact surface between the inner hook and the outer hook is reduced even under the non-lubricating condition, and the seizure is prevented. This makes it possible to maintain a beautiful sewing state over a long period of time.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a guide groove and a guide protrusion in a first embodiment of a shuttle of a sewing machine according to the present invention.

FIG. 2 is a schematic diagram showing a high-speed wear friction tester for measuring wear friction characteristics.

FIG. 3 is a graph showing the relationship between the rotation time of a shaft material and the clearance between the shaft material and the bearing material with respect to each test piece in a wear friction test under an oil-free condition.

FIG. 4 is a graph showing a relationship between a rotation time of a shaft member and a friction coefficient between the shaft member and the bearing member with respect to each test piece of a wear friction test under an oil-free condition.

FIG. 5 is a graph showing a result of a sewing test under a non-lubricating condition in a conventional sewing machine hook.

FIG. 6 is a graph showing a result of a sewing test under oil-free conditions of the first embodiment.

FIG. 7 is a graph showing a clearance between a guide groove and a guide protrusion with respect to a rotation time of a shuttle under a non-lubricating condition in a conventional shuttle of the sewing machine and the first embodiment.

FIG. 8 is an explanatory view showing another example of the first embodiment of the sewing machine hook according to the present invention.

FIG. 9 is an explanatory view showing another example of the first embodiment of the sewing machine hook according to the present invention.

FIG. 10 is an explanatory view showing a second embodiment of the sewing machine hook according to the present invention.

FIG. 11 is an explanatory view showing another example of the second embodiment of the sewing machine hook according to the present invention.

FIG. 12 is an explanatory view showing another example of the second embodiment of the sewing machine hook according to the present invention.

FIG. 13 is an explanatory view showing a conventional sewing machine hook.

[Explanation of symbols]

5 Outer pot 14 Guide groove 16 Inner pot 17 Guide projection 32 Steel material 33 Nickel-phosphorus-polytetrafluoroethylene coating layer 34 Polyimide resin

Claims (3)

[Claims] An outer hook having a guide groove formed on an inner peripheral surface is supported at an end of a lower shaft, and a guide projection is formed inside the outer hook to accommodate a bobbin and fit into a guide groove of the outer hook. In a sewing machine hook that supports the inner hook that is rotatable relative to the outer hook, a surface of one of the guide groove of the outer hook and the guide protrusion of the inner hook has a coating layer made of nickel-phosphorus. A sewing machine hook comprising: a composite layer in which a fluororesin is dispersed; and the other sliding contact portion in sliding contact with the composite layer is formed of a synthetic resin. 2. The apparatus according to claim 1, wherein the outer pot and the inner pot are formed using a metal material selected from a heat-treated steel material, stainless steel, and an aluminum alloy as a base material. Sewing machine pot. 3. The sewing machine pot according to claim 1, wherein a polyimide resin or an oil-containing polyimide resin is used as the synthetic resin.