JPH08869A - Forming method for hardened bayonet tip for outer shuttle - Google Patents

Abstract

PURPOSE:To prevent burrs or chipping from being generated even when the top end part of a bayonet tip hits a needle by improving strength for the top end part of the bayonet tip. CONSTITUTION:A fitting part 7 is formed at the top end part of a bayonet chip 3, and a fine chip 4 equipped with an acute angle part 4e for hanging an upper thread at the time of sewing work is formed by using a material of which hardness and flexibility is higher than that of a material for a main body 2 of the outer shuttle. Then, the fine chip 4 is fitted to the fitting part 7 while turning the acute angle part 4e forward along the rotating direction of the outer shuttle and after this fitting, a grinding margin part 10 of the bayonet tip 3 is ground so that a slope part 4c of the fine chip 4 and the front edge of the bayonet tip 3 can be continued with no step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a hardening type point of an outer hook used in a sewing machine.

[0002]

2. Description of the Related Art An outer hook, which is rotationally driven in a state where an inner hook is housed, is formed with a sword tip for hooking an upper thread held by a needle which is driven up and down. Here, during the sewing work in which the needle holding the upper thread is driven to move up and down and the outer hook is driven to rotate, the tip of the sword tip may hit the needle, causing burrs or chipping at the tip of the sword. Burrs and chippings occur at the tip of the sword tip, so that the sword tip is less likely to be caught by the upper thread, and the upper thread is likely to break.

[0003]

Therefore, when burr or chipping occurs at the tip of the sword, the tip is returned to a sharpened state by polishing the sword with a buff or the like. The work requires skill and is time-consuming. Furthermore, if the distance between the tip of the sword tip and the needle becomes larger than a predetermined value by performing such polishing, the position of the hook base holding the outer hook must be adjusted to the needle lift position. Of course, this position adjustment is very troublesome.

For this reason, there is a great demand for a hardening type blade tip that does not cause burr or chipping even when the tip of the blade tip hits the needle.

[0005]

According to the first aspect of the present invention,
A microchip having two plane portions parallel to each other and an inclined surface portion diagonally intersecting these flat portions and having an acute angle portion sandwiched by the one flat portion and the inclined surface portion of the outer pot main body It is made of a material with higher hardness and toughness than the material, and a sword tip with a polishing allowance portion at the front edge along the rotation direction of the outer hook is formed on the outer hook main body, and the minute tip is attached to the tip of this sword tip. A mounting portion for mounting is formed, and the minute tip is mounted on the mounting portion with the acute angle portion facing forward along the rotation direction of the outer pot, and after this mounting, the inclined surface portion and the front end edge of the sword tip have no step. The polishing margin was polished so as to be continuous.

According to a second aspect of the present invention, in addition to the first aspect of the invention, the microchip is attached to the attachment portion by brazing using a brazing furnace.

According to a third aspect of the invention, in the first aspect of the invention, the microchip is formed of cemented carbide.

[0008]

According to the first aspect of the present invention, the fine tip formed of a material having higher hardness and higher toughness than the material of the outer pot main body is attached to the attachment portion formed at the tip of the sword tip, so that the fine tip is sewn during sewing work. Even when it hits the needle, burrs and chippings are prevented from occurring, polishing work for removing the burrs and chippings is not necessary, and the durability of the outer pot is improved. Further, since the polishing process performed after the microchip is mounted on the mounting portion is performed on the polishing margin portion of the front end edge of the sword tip made of a material softer than that of the microchip, the microchip is inclined by this polishing process. It becomes easy to make the surface portion and the front end edge of the sword tip continuous without any step, and the needle thread hooked at the sword tip can be moved smoothly.

According to the second aspect of the present invention, the mountability of the microchip to the mounting portion is stable, and the outer pot having the microchip mounted can be mass-produced.

According to the third aspect of the present invention, the microtip has sufficient hardness and toughness, and even when the microtip hits the needle, burrs and chipping are prevented from occurring.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows the overall structure of the outer pot 1.
Is attached to the tip of the sword tip 3 formed on the outer hook main body 2.
The microchip 4 made of cemented carbide, which is a material having higher hardness and higher toughness than the above material, is attached to the outer hook main body 2 and a predetermined polishing process is performed. It is formed by screwing.

FIG. 1 shows a state in which the microchip 4 is attached to the outer pot main body 2, and the outer pot main body 2 has the outer pot 1
The sword tip 3 extending forward along the rotation direction of the sword tip 3 is formed, and the tip of the sword tip 3 has the minute tip 4
A mounting portion 7 for mounting is formed. Here, a mounting surface 8 on which the microchip 4 is mounted and a stopper 9 for positioning the mounting position are formed on the mounting portion 7. A polishing margin portion 10 is formed on the front end edge of the sword tip 3 along the rotation direction of the outer hook 1.

Next, as shown in FIG. 2, the microchip 4 is formed by cutting a cemented carbide round bar 11 by two parallel surfaces which are diagonally intersecting with the center line of the round bar 11. The formed microchip 4 has two plane portions 4a and 4b parallel to each other and curved inclined surface portions 4c and 4d diagonally intersecting the plane portions 4a and 4b. In addition, the flat surface portion 4a and the inclined surface portion 4
It has an acute-angled portion 4e sandwiched by c and an acute-angled portion 4f sandwiched by the flat surface portion 4b and the inclined surface portion 4d. And
The flat surface portions 4a and 4b are formed in a substantially elliptical shape having a major axis direction of about 1.2 mm and a minor axis direction of about 0.8 mm.
The thickness dimension between b is formed to be about 0.3 to 0.5 mm, and the angles of the acute-angled portions 4e and 4f are formed to be about 45 °. The end surface of the stopper 9 facing the microchip 4 is formed in an arc shape by an end mill or the like so as to match the shape of the acute angle portion 4f.

In such a structure, first, the outer pot main body 2 and the microchip 4 are separately formed, and the microchip 4 is formed.
Is attached to the mounting portion 7 by brazing non-oxidizing copper using a brazing furnace. When this non-oxidized copper brazing is performed, one surface portion 4b of the microchip 4 is coated with copper paste, and the microchip 4 is mounted on the mounting surface 8 with the surface portion 4b facing the mounting surface 8. Place on one of the sharp corners 4
The mounting position of the microchip 4 is positioned by directing e toward the front along the rotation direction of the outer pot 1 and abutting the other acute angle portion 4f against the stopper 9. Here, since the end surface shape of the stopper 9 is formed in conformity with the shape of the acute angle portion 4f of the microchip 4, the mounting position of the microchip 4 can be reliably and easily positioned. Then, the outer pot main body 2 having the microchips 4 placed on the mounting surface 8 is put into a brazing furnace and heated to about 1100 ° to bond the microchips 4 to the mounting surface 8.

In the state after the microchip 4 is adhered to the mounting surface 8 and before the polishing process is performed, as shown in FIG.
As shown in (a), the polishing allowance portion 10 formed on the front end edge of the sword tip 3 is in a state of protruding forward from the inclined surface portion 4c of the minute tip 4 along the rotation direction of the outer pot 1, and A large gap is formed between the tip portion of the stopper 9 and the inclined surface portion 4d. Therefore, polishing is performed, and as shown in FIG. 3B, the polishing allowance portion 10 is polished so that the inclined surface portion 4c and the front end edge of the sword tip 3 are continuous without a step.
Furthermore, the gap between the stopper 9 and the inclined surface portion 4d is reduced by polishing and shrinking the tip portion thereof. By making the inclined surface portion 4c and the front end edge of the sword tip 3 continuous without a step, when the upper thread hooked at the sword tip 3 moves along the inclined surface portion 4c and the front end edge of the sword tip 3, the movement is smooth. Done. In addition, the tip of the stopper 9 and the inclined surface 4
By making the gap with d smaller, it is possible to prevent the upper thread from being caught in this gap.

Since the microchip 4 is mounted on the mounting portion 7 by brazing a non-oxidizing copper using a brazing furnace, the mounting state of the microchip 4 on the mounting portion 7 is stable and mass production is possible. The property is improved.

As described above, when the outer hook 1 having the minute tip 4 made of cemented carbide attached to the tip of the sword tip 3 is used for sewing work, the tip of the sword tip 3 holds the upper thread. Even when it hits a needle that moves up and down, the microchip 4 is not burred or chipped, and the polishing work for removing the burr or chipping is unnecessary, and the durability of the outer pot 1 is greatly improved.

In the present embodiment, the case of forming the microchip 4 by obliquely cutting the round bar 11 has been described as an example, but the method of forming the microchip 4 is not limited to this. Instead, it may be formed by injection or the like.

In the present embodiment, the microchip 4 having the two sharp corners 4e and 4f has been described as an example, but the shape of the microchip is such that it has one sharp corner for hooking the needle thread. Of course, the microchip 4 described in this embodiment may be divided into two halves in a direction orthogonal to the major axis direction. In that case, the end surface of the stopper 9 has a planar shape.

[0020]

As described above, the invention according to claim 1 has two plane portions which are parallel to each other and an inclined surface portion which obliquely intersects these plane portions, and one of the plane portion and the inclined portion. A fine tip having an acute angle portion sandwiched by the surface portion is formed of a material having higher hardness and higher toughness than the material of the outer pot main body, and the blade point provided with a polishing allowance portion at the front edge along the rotation direction of the outer pot is described above. A mounting portion is formed on the outer pot main body, and a mounting portion for mounting the microchip is formed on the tip of the sword tip, and the microchip is mounted on the mounting portion with the acute angle portion facing forward along the rotation direction of the outer pot. At the same time, after this mounting, the polishing margin is polished so that the inclined surface and the front end edge of the sword tip continue without a step, so burr and chipping are prevented even if a minute tip hits the needle during sewing work. Do Therefore, the polishing work for removing burrs and chippings is not required, the work efficiency of the sewing work can be improved, and the durability of the outer hook can be significantly improved. The polishing process performed after mounting on the mounting part is performed on the polishing margin of the front end edge of the sword tip, which is made of a material that is softer than that of the microtips. It is easy to make the edge continuous without any step, and the upper thread hooked with the tip of the sword can be moved smoothly.

According to the second aspect of the invention, as described above, in the first aspect of the invention, the minute chips are attached to the mounting portion by brazing using a brazing furnace. This has effects such that the mountability of the chips can be stabilized and the mass of the outer pot to which the minute chips are mounted can be mass-produced.

As described above, in the invention according to claim 3, in the invention according to claim 1, since the microtips are formed of cemented carbide, the microtips have sufficient hardness and toughness, and therefore, at the time of sewing work. Even if the minute tip hits the needle, it is possible to prevent burrs and chipping from occurring.

[Brief description of drawings]

FIG. 1 is a front view showing a mounting state of a microchip on an outer pot main body.

2A and 2B show the shape of a microchip, wherein FIG. 2A is a front view showing a cutting direction when a round bar is cut to form a microchip, FIG. 2B is a front view of the microchip, and FIG. [Fig. 3] is a plan view of a microchip.

FIG. 3 is a front view showing a mounting state of a microchip on a mounting portion, where (a) is before polishing and (b) is after polishing.

FIG. 4 is a front view showing the overall structure of an outer pot.

[Explanation of symbols]

 1 Outer Kettle 2 Outer Kettle Main Body 3 Blade Point 4 Micro Tip 4a, 4b Flat Surface 4c Sloping Surface 4e Sharp Edge 7 Mounting Area 10 Polishing Allowance Area

Claims (3)

[Claims] 1. A microchip having two plane portions which are parallel to each other and an inclined surface portion which obliquely intersects these plane portions, and an acute angle portion which is sandwiched by the one flat portion and the inclined surface portion. Is made of a material having higher hardness and toughness than the material of the outer hook main body, and a sword tip having a polishing allowance portion at the front end edge along the rotation direction of the outer hook is formed on the outer hook main body and the tip portion of this sword tip is formed. And a mounting portion for mounting the microchip on the front surface of the inclined surface and the tip of the sword tip after mounting the microchip toward the front along the rotation direction of the outer pot with the acute angle portion facing forward. A method for forming a hardened blade point of an outer pot, wherein the polishing margin portion is polished so that the edge and the edge are continuous without any step. 2. The method for forming a hardened tip of an outer pot according to claim 1, wherein the microchip is attached to the attaching portion by brazing using a brazing furnace. 3. The method for forming a hardened blade point of an outer pot according to claim 1, wherein the minute tip is made of cemented carbide.