JPH06327873A - Hook retainer in final sewing machine - Google Patents

Abstract

PURPOSE:To reduce the fiction between a railway for an inner shuttle and a rail groove for an outer shuttle which can therefore be rotated by a small torque. CONSTITUTION:An inner hook retainer 6 in a sewing machine is formed out of (a) synthetic resin such as liquid crystal polymer or polytetrafluoroethylene, alone or (b) a synthetic resin containing metal powder, carbon fibers, glass particles or ceramic powder, and friction between a railway for an inner shuttle 3 and a rail groove 7 for an outer shuttle 2 is reduced, thereby it is possible to smoothly and stably rotate the outer hook 2 at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner hook presser foot of a lockstitch sewing machine such as a vertical full rotary hook or a horizontal full rotary hook.

[0002]

2. Description of the Related Art A conventional rotary full rotary hook of a sewing machine is made of steel, and therefore friction between an inner hook rail and an outer hook rail groove into which the rail fits is large, so that the outer hook is rotationally driven. There is a demand to reduce the torque required to do so that the quality of the sewn product can be improved.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the friction between the inner hook rail and the outer hook groove so that the outer hook can be rotationally driven with a small torque. It is to provide the inner hook of the sewing machine.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a lockstitch sewing machine that guides a rail of an inner hook by a rail groove formed by an outer hook body and an inner hook retainer detachably attached to the outer hook body. The inner hook presser for a lockstitch sewing machine is characterized in that (a) synthetic resin or (b) synthetic resin containing metal powder, carbon fiber, glass particles, or ceramic powder.

Further, the invention is characterized in that the synthetic resin is a liquid crystal polymer.

The present invention is also characterized in that the synthetic resin is polytetrafluoroethylene.

The invention is also characterized in that it is one of the group consisting of a vertical full-turn hook, a horizontal full-turn hook and a half-turn hook.

[0008]

According to the present invention, the inner hook holder of the vertical full-rotation rotary hook or the horizontal full-rotation rotary hook is detachably attached to the outer hook body, and is formed by the outer hook body and the inner hook holder. Guides the inner rail. Since the inner hook retainer is formed of (a) synthetic resin or (b) synthetic resin containing carbon powder, carbon fiber, glass particles or ceramic powder, the inner hook rail and the outer hook rail groove are separated from each other. Friction is reduced, the torque for rotational driving of the outer hook is reduced, and smooth and stable high-speed rotation of the outer hook is enabled, whereby the quality of the sewn product can be improved.

The synthetic resin is, for example, a liquid crystal polymer or polytetrafluoroethylene.

[0010]

1 is a sectional view of a vertical full-rotation rotary hook 1 with a bobbin and a bobbin case according to an embodiment of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is an inner hook holder. 6 is a perspective view of the outer hook main body 4 in a state where 6 is attached, FIG.
FIG. 3 is an exploded perspective view of an inner hook 3, an inner hook presser 6 and an outer hook main body 4.

The vertical full-rotation rotary hook 1 has an outer hook 2 and an inner hook 3, and the outer hook 2 is composed of an outer hook body 4, an inner hook presser 6 and a spring plate 18. As shown in FIG. 3, the outer hook body 4 has a sword tip 17, a semi-circular inner hook retainer 6 is detachably attached to the outer hook body 4 by a screw 19a, and a spring plate 18 is provided. It is attached by a screw 19b at a position different from the inner hook presser 6 in the circumferential direction. The track groove 7 is a first groove formed on the inner peripheral surface of the outer hook body 4.
And a second rail groove portion 7b formed by the inner hook holder 6 and an outer hook body 4 which is connected to the first rail groove portion 7a and to which the inner hook holder 6 is attached.

As shown in FIG. 4, the inner hook 3 is basically a cylindrical portion 10, a rail 8 formed on the outer periphery of the cylindrical portion 10, and an inner hook 3 formed at one end of the cylindrical portion 10. It has a flange portion 12 having a detent recess 11 and a bottom portion 13 formed at the other end of the tubular portion 10. A stud 14 is provided upright on the bottom 13 of the inner hook 3. The stud 14 is inserted through the bobbin, and the tip of the stud 14 is locked to the bobbin case 9.
The rail 8 fits into the rail groove 7 formed in the outer hook 2,
The outer hook 2 is rotationally driven at a high speed. The needle 16 is reciprocally driven up and down along a moving path perpendicular to the rotation axis of the outer hook, and the needle thread 15 is inserted into the needle 16. A needle drop hole 22 is formed in the inner hook 3. When the needle 16 is lowered by inserting the needle hole 53 of the sewing machine bed 50 up to the needle drop hole 22, the needle thread 15 moves the needle thread 15 of the outer hook 2. The inner hook 3 is passed over while forming an upper thread loop (not shown) and is engaged with the lower thread to form a stitch on the two cloths 51 and 52.

The inner hook presser 6 is attached to the outer hook main body 4 with screws 19a as shown in FIG. 4, and is (a) synthetic resin, or (b) metal powder, carbon fiber, glass particles or ceramic powder. It is formed of a synthetic resin containing the above. The synthetic resin a is made of a liquid crystal polymer, for example.

The liquid crystal polymer having a rod-shaped rigid component in the main chain of the polymer has a large intermolecular force between the rigid linear components and is well oriented and crystallized at the time of molding, so that its heat resistance is extremely excellent. However, even if the temperature of the outer hook 2 which is driven to rotate at a high speed increases due to friction, the heat deformation temperature is extremely high, and therefore the deformation does not occur. Further, the liquid crystal polymer,
It is composed of rigid molecular chains, and has high strength and high elastic modulus because it is highly oriented in the flow direction when molding.Because the molecular chains are arranged in a stretched state with respect to the orientation direction, tensile force is It exhibits excellent creep properties with almost no further elongation when added. In addition, the coefficient of linear expansion is extremely small, especially the coefficient of linear expansion in the flow direction is 1 × 10 ^-5.
It is about cm / cm / ° C. Such a linear expansion coefficient is one digit lower than that of other synthetic resins, and it is possible to obtain dimensional stability equivalent to that of metal. From this, the dimensional change due to the difference in environmental temperature and humidity such as summer and winter is almost zero. Further, since this liquid crystal polymer has high weather resistance, it can be used for a long time. In addition, since the liquid crystal polymer has a similar structure in a molten state and a solidified state, the phase change is slight and the volume change upon solidification is small.

A very interesting characteristic of the liquid crystal polymer is a characteristic of damping vibration. Generally, a soft material such as rubber is excellent in the property of damping vibration, but the liquid crystal polymer has a large vibration damping property while having a high elastic modulus. In order to improve the abrasion resistance, 30% of carbon fiber may be mixed with the liquid crystal polymer in order to reduce the specific abrasion amount and the dynamic friction coefficient. The liquid crystal polymer is composed of a copolymer of parahydroxybenzoic acid and 2-hydroxy-6-naphthoic acid. As another material, two or more kinds of naphthalene groups may be used as a constituent component of the main chain bond and a copolymer with another constituent component may be used. The naphthalene group has 1.2-position, 1.4-position, 1.5-position, 1.
A compound having a functional group at two or more substitution positions selected from the 8-position, 2.3-position, 2.6-position and 2.7-position, and the functional group is capable of forming a polyester and / or a polyesteramide. Any functional group may be used. That is, the functional group is selected from a hydroxy group, a carboxyl group, an amino group, an ester group and the like.

The naphthalene group may be hydroxynaphthoic acid, dihydroxynaphthalene and / or naphthalenecarboxylic acid.

The constituents other than the naphthalene group are the p-position phenyl group, the 4,4'-biphenyl group and / or the general formula of Chemical formula 1, that is,

[0018]

[Chemical 1]

(Where X is alkylene (having 1 to 1 carbon atoms)
4), alkylidene (having 1 to 4 carbon atoms), -O-, -S
-, - SO -, - SO 2 -, - group selected from CO-,
R and R'are reactive groups such as a hydroxy group and a carboxyl group or their esters. ) And a substituted derivative thereof. Further, the polymer binding unit is preferably an ester and / or an ester amide, and the functional group forming them is selected from a hydroxy group, a carboxyl group, an amino group, an ester group and the like, and preferably terephthalic acid, hydroquinone, p-diene Acetoxyphenylene, p-hydroxybenzoic acid and their esters, 4,4'-dihydroxybiphenyl, 4,4'-dicarboxybiphenyl, 4-hydroxy-4'-carboxybiphenyl and their esters, general formula 1 X is methylene, propenyl, or -SO ₂ of the formula - a is the dihydroxy form, dicarboxylic body, hydroxy carboxy bodies and their esters are selected, more preferably, terephthalic acid, Ferokishi benzoic acid, 4,4'- Dihydroxybiphenyl, 4,
4'-Dicarboxybiphenyl and their esters are selected.

By using the inner hook presser 6 made of such a liquid crystal polymer, since the track groove 7 is formed by the inner hook presser 6 and the outer hook main body 4, even if the sewing operation is performed at high speed for a long period of time, The wear of the surface of the rail 8 is extremely small, and the durability can be remarkably improved.
In addition, it is light in weight, and the rotational torque of the rotary shaft 5 is small, which makes it possible to downsize the motor for rotationally driving the rotary shaft 5.

FIG. 5 is a sectional view in which a part of the liquid crystal polymer injection molded product 28 is cut away. The liquid crystal polymer has an outer skin layer 29 in which molecular chains are highly oriented in the flow direction,
It includes an inner skin layer 30 and a core layer 31 whose orientation is not clear. The thickness of the skin layers 29 and 30 is approximately constant at 0.3 to 0.2 mm regardless of the thickness of the molded product. The liquid crystal polymer is plasticized by heating and pressed into a closed mold, cooled and solidified, and then the mold is opened and taken out. As described above, since the inner hook presser 6 can be manufactured by molding the liquid crystal polymer with a die, the manufacturing is easy and the productivity is improved.

The liquid crystal polymer is used for each skin layer 29, 3
Since 0 is strongly oriented in the flow direction, it has excellent mechanical properties such as high strength and high elastic modulus. However, since it is easy to orient, anisotropy is likely to occur. Therefore, in order to reduce this anisotropy, it is preferable to introduce a reinforcing agent into the rigid skeleton. Further, since they are easily oriented, fibrils peeled off from the skin layers 29 and 30 are likely to occur. Macrofibril 32 is 5
μm, the fibril 33 is 0.5 μm, and the microfibril 34 is 0.05 μm. The liquid crystal polymer has a multilayer structure including an outer skin layer 29, an inner skin layer 30, a core layer 31 and the like, and has a high elastic modulus,
It exhibits large vibration damping characteristics.

As the synthetic resin b containing the above-mentioned metal powder, carbon fiber, glass particles or ceramic powder,
For example, it may be a composite of a synthetic resin and a metal. The composite of the synthetic resin and the metal is formed, for example, by filling an epoxy resin with a metal fiber such as aluminum or brass. The metal fiber has a thickness of about 0.01 mm. As a result, mechanical strength such as tensile strength and compressive strength is improved, and the tensile strength is increased about 5 times by adding 35% of the metal fiber.

Further, an epoxy injection molding resin in which an aluminum powder or an iron powder is filled in an epoxy resin is preferable,
This increases the mechanical strength.

As another embodiment of this embodiment, carbon powder or carbon fibers may be added to the synthetic resin instead of the metal in the composite of the synthetic resin and the metal.

Further, the inner hook holding member 6 may be made of synthetic resin which is reinforced by mixing glass powder. A ceramic coating layer may be formed on the surface thereof.

This ceramic is generally aluminum oxide (Al ₂ O ₃ ) or a mixture of a small amount of other metal oxides and a binder, which is press-molded and sintered at about 1100 ° C. The hardness does not change to a certain degree. The specific heat is about four times that of cemented carbide, and the thermal conductivity is about half that of cemented carbide, and the thermal expansion is small. Moreover, although cemented carbide is considerably oxidized and denatured at about 1000 ° C or higher, ceramic is stable up to about 2000 ° C, and because it has a low affinity for most metals, it does not easily weld to other objects and wears. It has the property of being strong.

The inner hook presser 6 on which such a ceramic coating layer is formed is manufactured by injection molding.

Since the inner hook retainer 6 is manufactured by injection molding, it is extremely easy to manufacture. In order to further improve the accuracy, the coating layer may be cut. A plurality of coating layers can be formed, the lower layer can be subjected to a cutting process, etc., and then an upper layer can be formed to make the outer peripheral surface of the coating layer smooth, that is, without unevenness. In this way, the inner hook presser 6 is made of a material in which glass powder is mixed with a synthetic resin, so that the inner hook presser 6 can be manufactured by injection molding using a mold, and the productivity can be remarkably improved. Moreover, since the inner hook presser 6 is mixed with glass powder, it is possible to improve the strength as compared with the case where only the synthetic resin is used, and it is possible to reduce the weight as compared with the metal part.

Further, since the coating layer is formed on the surface of the inner hook presser 6 and the component is made of plural kinds of materials, abnormal phenomena such as resonance can be prevented and noise can be reduced.

Further, since the coating layer is made of ceramic, it has excellent heat resistance and wear resistance, and can prevent seizure and the like from occurring in the mutually sliding portions.
Moreover, since the ceramic coating layer has a small friction, the rail 8 of the inner hook 3 smoothly rotates along the rail groove 7 formed by the outer hook main body 4 and the inner hook presser 6. By thus preventing seizure and reducing the amount of wear, it becomes possible to prolong the service life of the parts and improve the durability.

The coating layer is formed by forming a first coating layer on the surface of the inner hook presser 6 and cutting it, and then forming a second ceramic coating layer on the surface of the first coating layer. Alternatively, the second coating layer on the first coating layer, which has already been machined into a substantially flat shape, has almost no large unevenness, so that the polishing amount is small,
It is possible to reduce waste of material as much as possible, and reliably obtain a predetermined thickness with the thin first and second coating layers.

As still another embodiment of the present invention, polytetrafluoroethylene (abbreviated as "PTF") is attached to the inner hook holder 6.
E ”) may be used. PTFE is a copolymer of tetrafluoroethylene, has excellent heat resistance, chemical resistance, and impact resistance, and can prevent the occurrence of seizure or the like in sliding parts.

As described above, since PTFE is used for the inner hook presser 6, even if the sewing operation is performed at high speed for a long period of time, the wear of the surfaces of the track groove 7 and the track 8 is extremely small, and the durability is remarkably improved. can do.

FIG. 6 is a perspective view showing the outer hook 42 in a state in which the inner hook holder 46 of the horizontal full-turn hook according to another embodiment of the present invention is mounted, and FIG. 7 is the inner hook 43 and the inner hook holder 46.
FIG. 3 is an exploded perspective view of an outer hook body 44. Outer bite 42
Is composed of an outer hook body 44 and an inner hook presser 46. A rotary shaft 45 is integrally formed on the bottom of the outer hook body 44,
A sword tip 57 is formed at one end in the circumferential direction of the substantially C-shaped peripheral wall of the outer hook main body 44, and an inner hook pressing member 46 is attached to the other end in the circumferential direction of the peripheral wall for about half a circumference by using screws 59. . The track groove 47 includes a first track groove portion formed on the inner peripheral surface of the outer hook body 44, and a first track groove portion 47a.
And a second rail groove portion 47b formed by an outer hook body 44 and an inner hook presser 46. The track groove 47
The rail 48 of the inner rotary hook 43 is fitted in the inner rotary hook 43, and the horizontal full rotary rotary hook is driven to rotate about a rotation axis substantially parallel to the moving path of the needle.

The inner hook presser 46 is the same as that shown in FIGS.
Similar to the embodiment shown in FIG. 2, it is formed of (a) synthetic resin or (b) synthetic resin containing carbon powder, carbon fiber, glass particles or ceramic powder, and the rail 48 of the inner hook 43 and the outer hook 42. The outer hook can be smoothly rotated at a high speed by reducing the friction with the rail groove 47.

Further, the inner hook holding body is made of metal, and a coating layer made of (a) synthetic resin or (b) synthetic resin containing carbon powder, carbon fiber, glass particles or ceramic powder is formed on the outer peripheral surface thereof. Then, the inner hook may be configured.

[0038]

As described above, according to the present invention, the friction between the rail of the inner hook and the groove of the outer hook is reduced, the torque required to drive the outer hook is reduced, and the outer hook is driven at high speed. With this, it is possible to stably and smoothly rotate and improve the quality of the sewn product.

[Brief description of drawings]

FIG. 1 is a sectional view of a vertical full rotation rotary hook 1 according to an embodiment of the present invention.

FIG. 2 is a front view of the vertical full rotation rotary hook 1 shown in FIG.

FIG. 3 is a perspective view of an outer hook body 4 with an inner hook retainer 6 of the vertical full rotation hook 1 shown in FIG. 1 attached.

4 is an exploded perspective view of an inner rotary hook 3, an inner rotary hook retainer 6 and an outer rotary hook main body 4 of the vertical full rotary rotary hook 1 shown in FIG. 1. FIG.

FIG. 5 is a cross-sectional view in which a part of a liquid crystal polymer injection molded product 28 is cut away.

FIG. 6 is a perspective view showing an outer hook 42 of a horizontal full rotation hook according to another embodiment of the present invention.

7 is an exploded perspective view of an inner hook 43, an inner hook presser 46, and an outer hook main body 44 of the horizontal full-rotation rotary hook shown in FIG.

[Explanation of symbols]

 1 Vertical full rotary hook 2,42 Outer hook 3,43 Inner hook 4,44 Outer hook main body 6,46 Inner hook retainer 7,47 Track groove 8,48 Rail

Claims (4)

[Claims] 1. An inner hook presser for a lockstitch sewing machine for guiding the inner hook rail by a rail groove formed by an outer hook main body and an inner hook presser removably attached to the outer hook main body, wherein (a) An inner hook presser foot for a lockstitch sewing machine, which is made of a synthetic resin or (b) a synthetic resin containing metal powder, carbon fiber, glass particles or ceramic powder. 2. The inner hook presser foot for a lockstitch sewing machine according to claim 1, wherein the synthetic resin is a liquid crystal polymer. 3. The inner hook presser foot for a lockstitch sewing machine according to claim 1, wherein the synthetic resin is polytetrafluoroethylene. 4. The inner hook presser foot for a lockstitch sewing machine according to claim 1, wherein the inner hook holder is one of the group consisting of a vertical full-turn rotary hook and a horizontal full-turn rotary hook.