JPH05317559A - Parts of sewing machine - Google Patents

Abstract

PURPOSE:To improve the wear resistance and durability and to reduce the weight and size of the parts of sewing machines, such as rotating hook, rotating hook bobbin case holder, looper, needle thread take-up, presser foot and rolled hemming foot by forming then with liquid crystal polymers. CONSTITUTION:The parts of sewing machines, such as rotating hook 3, rotating hook bobbin case holder and bobbin case 5 of a perpendicularly fully rotating hook 1 and others, such as looper, needle thread take-up, presser foot and rolled hemming foot are formed of the liquid crystal polymers. The liquid crystal polymers have a high modulus of elasticity and can efficiently attenuate vibrations; in addition, the liquid crystal polymers less expand linearly and can, therefore, decrease the friction of vibrating parts, greatly improve the wear resistance and reduce the weight. The driving power for driving these parts is thus decreased. Further, the production of the parts is easy and the productivity is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a part such as an outer hook, an inner hook or a looper provided in a lockstitch sewing machine.

[0002]

2. Description of the Related Art For example, an outer hook which is a component provided in a lockstitch sewing machine is made of steel or stainless steel, a rail groove is formed on an inner peripheral surface thereof, and a sword tip or the like is provided on the outer peripheral surface thereof with screws or the like. It has a relatively complicated structure. A rail formed on the outer peripheral surface of the inner hook is fitted into the rail groove of such an outer hook, and the inner hook is fixed to the machine body of the sewing machine by an inner hook stopper member which is located on the downstream side in the outer hook rotating direction. Only the outer hook is driven to rotate at a high speed while the rotation to the is blocked. Therefore, the rail groove slides in the rail while causing great wear, and it is desired to improve wear resistance in order to reduce this friction. Further, in order to improve the thread slippage, it is desired that the surface near the tip of the sword tip, the outer peripheral surface of the inner hook, or the surface of the balance with which the upper thread or the lower thread makes sliding contact have high wear resistance.
Further, it is preferable that the displacement driven parts such as the outer hook or the balance have a torque or power for driving these parts as small as possible to miniaturize the structure of the power source such as the motor.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sewing machine part which is improved in wear resistance and can be reduced in weight.

[0004]

SUMMARY OF THE INVENTION The present invention is a sewing machine component characterized by comprising a liquid crystal polymer.

The present invention also extends to a sewing machine characterized in that it is made of a liquid crystal polymer.

The invention also resides in a sewing machine characterized by comprising a liquid crystal polymer.

The present invention also provides a looper for a sewing machine, which is made of a liquid crystal polymer.

The present invention is also a balance for a sewing machine, which is made of a liquid crystal polymer.

The present invention is also a presser foot for a sewing machine, which is made of a liquid crystal polymer.

The present invention is also three volumes of a sewing machine characterized by comprising a liquid crystal polymer.

[0011]

According to the present invention, the parts of the sewing machine such as the outer hook, the inner hook, the looper, the presser foot and the triple winding are made of the liquid crystal polymer, so that the wear resistance is improved.
And it can be made lighter. As a result, the durability of each component can be improved, and the outer hook, looper, and balance can be lightened and driven with a small torque, and the power source can be downsized.

[0012]

1 is a perspective view showing a vertical full rotation rotary hook 1 according to an embodiment of the present invention. The vertical full-rotation rotary hook 1 is fixed to a lower shaft 2 which is rotationally driven around a horizontal axis of rotation, and an outer hook 3 which is rotationally driven in a direction of an arrow A, and an inner hook 4 which is housed in the outer hook 3. And a bobbin case 5 detachably attached to the inner hook 4.

The flange 6 on the open end side of the inner rotary hook 4 is formed with a rotary hook stopper recess 9 into which a projection 8 of a rotary hook stopper member 7 whose base end is fixed to a machine body of a sewing machine is fitted.
The rotation of the inner rotary hook 4 due to the rotation of the outer rotary hook 3 is prevented in a state where the protrusion 8 is fitted in the rotary hook stopper recess 9.

FIG. 2 is a front view of the outer hook 3. A rail groove 11 is formed on the inner peripheral surface of the peripheral wall 10 of the outer hook 3 and a rail 13 formed on the outer peripheral surface of the peripheral wall 12 of the inner hook 4 shown in FIG. Fit in. The outer hook 3 and the inner hook 4 are made of a liquid crystal polymer. 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. Even if the temperature increases due to the friction of the outer hook 3 that is rotationally driven at a high speed, the heat deformation temperature is extremely high and the deformation does not occur. Further, the liquid crystal polymer has a high strength and a high elastic modulus because it is made of a rigid molecular chain and is highly oriented in the flow direction at the time of molding, and the molecular chains are arranged in a fully extended state in the orientation direction. Therefore, even if a tensile force is applied, it does not extend any further and exhibits excellent creep characteristics. The coefficient of linear expansion is extremely small, and particularly the coefficient of linear expansion in the flow direction is about 1 × 10 ⁻⁵ cm / cm / ° C. Such a linear expansion coefficient is 1 compared to other synthetic resins.
The value is orders of magnitude lower, and it is possible to obtain dimensional stability equivalent to that of metal. Therefore, the dimensional changes due to the difference in environmental temperature and humidity such as summer and winter are 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 property of the liquid crystal polymer is a property of damping vibration. Generally, a soft material such as rubber is excellent in vibration damping characteristics, but a liquid crystal polymer has a large vibration damping characteristic while having a high elastic modulus. In order to improve the abrasion resistance, 30% of carbon fibers 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 three 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, the functional group being 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 naphthalenedicarboxylic 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]

(However, X is alkylene (having 1 to 1 carbon atoms)
4) alkylidene (having 1 to 4 carbon atoms), -O-, -S-,
_{-SO -, - SO 2 -,} - CO- than group selected, R,
R'is a reactive group such as a hydroxy group or a carboxyl group or an ester thereof. ) 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 more 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, wherein X in the general formula of Formula 1 is methylene, propenyl or-
SO ₂ − of each dihydroxy form, dicarboxylic form,
A hydroxycarboxy derivative and an ester thereof are selected, and more preferably terephthalic acid, hydroxybenzoic acid, 4,4′-dihydroxybiphenyl, 4,4 ′.
-Dicarboxybiphenyl and their esters are selected.

Outer hook 3 made of such a liquid crystal polymer
Even if a high-speed sewing operation is performed using the inner hook 4 and the inner hook 4, the wear of the surfaces of the rail groove 11 and the rail 13 is extremely small, and the durability can be remarkably improved.
Moreover, since the outer hook 3 is lightweight, the rotational torque transmitted from the lower shaft 2 is small, which allows the lower shaft 2 to rotate.
It is possible to downsize the motor for rotating and driving.

FIG. 4 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. Since the outer hook 3 and the inner hook 4 can be manufactured by molding the liquid crystal polymer in this manner, 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, it is preferable to introduce a reinforcing agent into the rigid skeleton in order to reduce this anisotropy. 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 multi-layer 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.

FIG. 5 is a perspective view of the bobbin case 5.
The bobbin case 5 of this embodiment is also made of a liquid crystal polymer like the outer hook 3 and the inner hook 4 described above. As a result, even if the upper thread or the like slides on the surface 18 of the bobbin case 5 arranged on the inner hook opening side, the sliding resistance can be reduced as much as possible to prevent the change of the upper thread tension. This can improve the quality of sewing.

In yet another embodiment of the present invention, a bobbin 19 is formed from the liquid crystal polymer, as shown in FIG.

Further, as shown in FIG. 7, the balance 20
The crankshaft 21 is formed of the liquid crystal polymer described above. By forming parts such as the balance 20 and the crankshaft 21 on which such vibration acts from the above materials, it is possible to reduce the weight without reducing the strength and to reduce the power.

Further, the loopers 22 and 23 respectively shown in FIGS. 8 and 9 are made of the liquid crystal polymer. Further, a presser foot 24 as shown in FIG. 10 and a latch hummer (Latch Hemme) called a triple winding as shown in FIG.
r) 25, and the latch hammer 26 as shown in FIG. 12, is formed from the liquid crystal polymer. Since the parts such as the presser foot 24 and the latch hammers 25, 26 that come into contact with the material to be sewn such as cloth with a relatively large pressing force are formed of the liquid crystal polymer, the material to be sewn is slippery well. An undesirably large resistance force against a feeding operation of cloth or the like does not occur.

The present invention is not limited to the above-mentioned sewing machine parts,
The horizontal full-rotation rotary hook as shown in FIG. 13 can also be suitably implemented.

As still another embodiment of the present invention, the present invention can be suitably implemented with respect to other sewing machine parts, such as a driver and a center hook which constitute a half-turn rotary hook.

[0029]

As described above, according to the present invention, the outer hook,
Since the sewing machine parts such as the inner hook, looper, balance, presser foot, and triple winding are made of liquid crystal polymer, vibration can be efficiently damped with a high elastic modulus and linear expansion Since the amount of vibration is small, the friction of the vibrating portion is small, the wear resistance can be significantly improved, the weight can be reduced, and the power for driving the parts can be reduced.

Furthermore, since the parts of the sewing machine are made of liquid crystal polymer, the parts can be easily manufactured.
Productivity can be improved.

[Brief description of drawings]

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

FIG. 2 is a front view of an outer hook 3.

FIG. 3 is a front view of an inner rotary hook 4.

4 is a cross-sectional view of a liquid crystal polymer injection molded product 28. FIG.

5 is a perspective view of the bobbin case 5. FIG.

FIG. 6 is a perspective view of the bobbin 9.

FIG. 7 is a perspective view showing a balance 20 and a crankshaft 21.

8 is a perspective view of the looper 22. FIG.

9 is a perspective view of the looper 23. FIG.

FIG. 10 is a perspective view of a presser foot 24.

11 is a perspective view of a latch hummer 25. FIG.

FIG. 12 is a perspective view of a latch hammer 26.

FIG. 13 is a front view showing a horizontal full rotary hook 27 according to still another embodiment of the present invention.

[Explanation of symbols]

 1 Vertical full-rotation rotary hook 3 Outer rotary hook 4 Inner rotary hook 5 Bobbin case 11 Rail groove 13 Rail 19 Bobbin 20 Balance 21 Crankshaft 22,23 Looper 24 Presser foot 25,26 Latch hammer 27 Horizontal full rotary hook 28 Injection molded product

Claims (7)

[Claims] 1. A sewing machine component comprising a liquid crystal polymer. 2. An outer hook for a sewing machine, which is made of a liquid crystal polymer. 3. The inner hook of a sewing machine, which is made of a liquid crystal polymer. 4. A looper for a sewing machine, which is made of a liquid crystal polymer. 5. A balance for a sewing machine, which is made of a liquid crystal polymer. 6. A presser foot for a sewing machine, which is made of a liquid crystal polymer. 7. Three rolls of sewing machine, characterized in that they consist of a liquid crystal polymer.