JP2007167317A - Sewing machine components - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sewing machine with good abrasion-resistant, anti-seizing, and anti-sliding properties even in the condition that a supply of lubricant is restricted. <P>SOLUTION: A sewing machine 1 includes nitriding compound layer made of a porous layer and a dense layer formed on the surface of a base material composed of low-carbon steel and low-carbon alloy steel not applied with hardening treatment, on which an intermediate layer made of a metal layer such as Cr or W is interposed by a sputtering coating method and formed with a DLC layer over the intermediate layer. Interposing an intermediate layer between the base material and the DLC layer improves adhesiveness of the base material and the DLC layer. Forming a DLC layer on the very top surface improves the hardness of the surface and lubricity by reducing the friction resistance of the surface. By this durability of the same level as ordinary sewing machines which are supplied with lubricant forcibly can be achieved even under a dry condition where lubricant is not supplied forcibly. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sewing machine component in which a sliding portion between components is subjected to wear resistance treatment.

Conventionally, a sewing machine has been provided with a large number of sliding portions that allow parts to slide at high speed. For example, a sewing machine that performs sewing with two needles is provided with a well-known needle bar driving mechanism that can be driven up and down by selecting one or both of two needles. In such a needle bar drive mechanism, the needle bar drive link is rotatably connected to the main shaft connected to the sewing machine motor via an eccentric weight, and the needle bar drive link is connected to the needle bar drive link via a pin. It is pivotally connected. The needle bar holder has two needle bars for holding the sewing needle at the tip, and when sewing using only one of the two needle bars, the other needle The bar and the needle bar hug will slide.
By the way, these parts provided in the needle bar drive mechanism are made of low carbon steel or low carbon alloy steel whose processing costs are relatively low. Generally, when low-carbon steel or low-carbon alloy steel is used for the sliding portion, the surface is subjected to heat treatment such as carburizing, quenching and tempering in order to prevent wear and seizure of the sliding contact surface. The needle bar hug that selectively holds two needles has a complicated structure, so the thickness of the member is thin. When carburizing, quenching and tempering performed at a high temperature of 800 ° C. or higher, the member is Deformation cannot maintain dimensional accuracy. For this reason, a configuration has been adopted in which a tuftride process having a low processing temperature is performed and the sliding contact surface is forcibly lubricated by an oiling mechanism to prevent wear.
However, since there is a problem that if the oil supply mechanism is provided, the sewn product is soiled due to the scattering of oil, and in recent years, it has been desired to eliminate the need for oil supply using grease for lubrication. Here, although not in the field of sewing machines, as a technology applied to the sliding surface of the semiconductor substrate, in order to improve the lubricity of thin members while realizing no oil supply, the processing temperature is low and the surface hardness and sliding There is a conventional technique for applying a diamond-like carbon (hereinafter referred to as DLC) coating that is excellent in performance (see, for example, Patent Documents 1 and 2).
JP 2002-321026 A Japanese Patent Laid-Open No. 2002-210525

However, the techniques disclosed in Patent Document 1 and Patent Document 2 can cope with a small load acting on the sliding contact surface of the semiconductor substrate or the like, but with respect to a load acting on the sliding contact surface of the sewing machine. In some cases, the cured layer is thin and sufficient effects cannot be obtained.
In addition, when DLC coating is applied to the surface of a low-carbon steel base material (hereinafter simply referred to as raw material) that has not undergone hardening treatment, the adhesion is low due to the large hardness difference and sufficient thickness to withstand sliding. It was difficult to form a DLC film.

  The present invention has been made to solve the above-described problems, and provides a sewing machine component that is excellent in wear resistance, seizure resistance, and slidability even under conditions where lubricating oil supply is limited. Objective.

  In order to solve the above problems, the invention according to claim 1 is a sewing machine component in which a surface of a base material made of a steel material that has not been subjected to a hardening process by heating is subjected to wear resistance treatment. Forming a nitride film having a dense layer bonded to the base material and a porous layer bonded on the dense layer, further forming a DLC (diamond-like carbon) film with an intermediate layer interposed therebetween, The intermediate layer is a sewing machine component characterized in that a hardness region is located between the nitride film and the DLC film.

  A second aspect of the present invention is the sewing machine component according to the first aspect, wherein the DLC film is composed of one type of DLC film containing a metal.

  According to a third aspect of the present invention, in the sewing machine component according to the second aspect, the metal contained in the DLC film is Cr or W.

  According to a fourth aspect of the present invention, there is provided a sewing machine component in which a surface of a base material made of a steel material not subjected to a hardening treatment by heating is subjected to an abrasion resistance treatment, and a dense layer bonded to the base material on the surface of the base material. A nitride film having a porous layer bonded to the dense layer is formed, and an WC / C (tungsten carbide carbon) film is formed thereon by interposing an intermediate layer. The intermediate layer has a hardness of The sewing machine component is characterized in that the region is located between the nitride film and the WC / C film.

  According to a fifth aspect of the present invention, in the sewing machine component according to any one of the first to fourth aspects, the intermediate layer is made of Cr or W.

  According to a sixth aspect of the present invention, in the sewing machine component according to any one of the first to fifth aspects, the steel material that has not been subjected to the hardening treatment by heating is subjected to carburizing quenching tempering or quenching tempering treatment. It is a low carbon steel, a low carbon alloy steel or an alloy steel which is not performed at all.

  According to the first aspect of the present invention, by providing an intermediate layer having a hardness region located in the middle of both hardness regions between the nitride film and the DLC film, a residue generated between the nitride film and the DLC film. Stress is relieved and adhesion between the two is improved. Further, since the DLC film has an amorphous structure, a high hardness and smooth surface shape can be obtained. Therefore, the frictional resistance on the surface of the base material can be greatly reduced. Thereby, a smooth sliding operation can be realized and heat generation at the sliding portion is prevented. Furthermore, it is possible to configure a sewing machine component having excellent wear resistance and seizure resistance even in an environment where the supply of lubricating oil is restricted. In addition, a member having a thin portion that can be thermally deformed by quenching or the like can have a hard surface and good slippage, and can be used in a dry environment.

  According to the invention described in claim 2, in addition to obtaining the same effect as that of the invention described in claim 1, it is possible to further improve the adhesion when the intermediate layer is a metal by containing a metal in the DLC film. The DLC film can be firmly maintained even in a severe sliding environment.

  According to the invention described in claim 3, the same effect as that of the invention described in claim 2 can be obtained. Further, when the DLC film contains Cr or W, the intermediate layer is Cr or W. It is possible to improve the adhesion, and it is possible to maintain the DLC film firmly even in a severe sliding environment.

  According to the fourth aspect of the present invention, by providing an intermediate layer having a hardness region located between the two hardness regions between the nitride film and the WC / C coating, the nitride film and the WC / C coating are provided. The residual stress generated between them is relaxed, and the adhesion between the two is improved. Moreover, a high hardness surface can be obtained. Therefore, the frictional resistance on the surface of the base material can be greatly reduced. Thereby, a smooth sliding operation can be realized and heat generation at the sliding portion is prevented. Furthermore, it is possible to configure a sewing machine component having excellent wear resistance and seizure resistance even in an environment where the supply of lubricating oil is restricted. In addition, a member having a thin portion that can be thermally deformed by quenching or the like can have a hard surface and good slippage, and can be used in a dry environment.

  According to the invention described in claim 5, the same effect as that of any one of claims 1 to 4 can be obtained, and in particular, the intermediate layer is formed of Cr or W, and the base material The adhesion between the film and the film is further improved. That is, Cr or W has good adhesion to DLC or WC / C, and the DLC or WC / C film can be firmly maintained even under severe sliding environments.

  According to the invention described in claim 6, in addition to being able to obtain the same effect as the sewing machine part according to any one of claims 1 to 5, in particular, a thin-walled portion capable of causing thermal deformation by quenching or the like. With respect to a member having a surface, the surface thereof can be hardened and the sliding can be improved, and the use in a dry environment can be enabled.

Hereinafter, the best mode of a sewing machine according to the present invention will be described in detail with reference to the drawings.
In the present embodiment, a two-needle sewing machine that performs sewing with two needles will be described as an example of the sewing machine. In the following description, the vertical vertical direction is the Z-axis direction, the longitudinal direction of the arm portion of the two-needle sewing machine in a state of being installed on the horizontal plane is the Y-axis direction, and the Y-axis is parallel to the plate surface of the needle plate (not shown). The direction orthogonal to the direction is taken as the X-axis direction. The X-axis direction, the Y-axis direction, and the Z-axis direction are assumed to be orthogonal to each other.

(Overall configuration of the embodiment)
As shown in FIG. 1, a sewing machine (two-needle sewing machine) 1 according to an embodiment of the present invention converts a rotational movement of a main shaft 52 rotated by a sewing motor (not shown) into a reciprocating vertical movement along the Z-axis direction (not shown). A needle up / down movement mechanism is provided.
The sewing machine 1 has two needles, such as a needle swing mechanism that swings a needle bar support frame 55 described later and moves the tip of the sewing needle in the feed direction, and a feed mechanism that feeds the workpiece along the cloth feed direction. Various mechanisms for performing sewing according to the above are provided, but since these are the same as those conventionally known, they will not be described in detail in this embodiment.

The needle up-and-down movement mechanism is provided inside the tip of the sewing machine arm portion. Such a needle up-and-down moving mechanism includes a needle bar crank 54 whose one end is rotatably connected to an eccentric portion of an eccentric weight 53 provided at the tip of the main shaft 52, and a needle bar crank 54 which is rotatably connected to the other end of the needle bar crank 54. Needle bar holder 30 as a sewing machine part, two needle bars 10 held by the needle bar holder 30 and holding sewing needles at the tips, respectively, and these two needle bars 10 individually. A needle bar support frame 55 that regulates the moving direction of the two needle bars 10 by supporting the two needle bars 10 slidably up and down.
When the main shaft 52 rotates by driving the sewing machine motor, the needle bar holder 30 is driven up and down via the eccentric weight 53 and the needle bar crank 54. Thereby, the two needle bars 10 held by the needle bar holder 30 reciprocate up and down.

The needle bar holder 30 includes a clutch mechanism capable of selectively switching the holding of each needle bar 10 between a holding state and a releasing state, and the needle bar 10 released from the holding state by the clutch mechanism. And a switching mechanism 80 that selects one of the needle bars 10 by an artificial input operation and switches between a holding state and a releasing state in the clutch mechanism (see FIG. 3).
As shown in FIGS. 1 and 5, the clutch mechanism 60 includes a clutch member 61 as two sewing machine parts inserted into a circular support hole 57 penetrating from the front surface of the needle bar holder 51 to each insertion hole, and each clutch. A driven link 62 as two sewing machine parts that individually move the member 61 forward and backward, and two pressing springs 63 that individually apply a moving force in the forward direction to each clutch member 61 via each driven link 62; The latching claws 64 serving as two sewing machine parts that are respectively latched in the state in which the clutch members 61 are retracted (retracted positions), and the two pressing springs 65 that respectively press the latching claws 64 in the locking direction. And a release pin 66 as a sewing machine part capable of inputting an operation for releasing the locking by each locking claw 64 from the outside.
Then, when sewing is performed using only one of the needle bars 10 by artificially operating the switching mechanism 80, the other needle bar 10 is attached to the needle bar support frame 55 at the top dead center position. Retained. That is, since only one needle bar 10 is held by the needle bar holder 30, a sliding contact surface is formed between the needle bar holder 30 and the other needle bar 10. Each member of the clutch mechanism is also thin and slides with other members in its operation.

(Laminated structure of nitride film and DLC film)
Here, as shown in FIGS. 4 and 5, the needle bar holder 30 in the present embodiment is formed using a low carbon steel, a low carbon alloy steel or an alloy steel as a base material 31, and the surface thereof is nitrided. A nitride compound layer 32 made of a material is formed. Furthermore, in the sewing machine 1 according to the present embodiment, a DLC (diamond like carbon) layer 35 is formed on the nitride compound layer 32 via an intermediate layer 33 made of chromium (Cr).

As shown in FIG. 6, the base material 31 is formed of a mixed structure of ferrite portions and pearlite portions. That is, the base material 31 of the needle bar holder 30 in the present embodiment is a raw material of low carbon steel, low carbon alloy steel or alloy steel, that is, a steel material that has not been subjected to hardening treatment by heating such as carburizing, quenching and tempering. It is used.
Since the needle bar holder 30 in the present embodiment incorporates the various mechanisms described above, its thickness is 1.0 to 1.5 mm, which is thinner than that of a general needle bar holder 30. For this reason, in order to prevent deterioration of dimensional accuracy due to a hardening process such as carburizing quenching tempering or quenching tempering performed in a temperature range of 800 ° C. or higher, raw materials that are not subjected to such a process are used. The hardness of the base material 31 is 200HV to 300HV.

The nitride compound layer 32 (hereinafter referred to as the nitride layer 32) is formed on the surface of the base material 31 by salt bath soft nitridation treatment (tuftride treatment) in a low temperature region of 600 ° C. or less, and the dense nitride compound layer 32a. (Hereinafter referred to as a dense layer 32a) and a porous nitride compound layer 32b (hereinafter referred to as a porous layer 32b) on the outside thereof.
The treatment by the salt bath soft nitriding method is performed by the chemical reaction shown in the following (1) and (2).

2NaCN + O ₂ = 2NaCNO (1)

4NaCNO = 2NaCN + Na ₂ CO ₃ + CO + 2N (2)

Here, a nitride compound layer and a small amount of a carbide layer are formed on the surface of the low carbon alloy steel by thermal decomposition of NaCNO formed in the formula (1). By the salt bath soft nitriding treatment, a dense carbonitriding compound layer 32 a is formed in a portion in contact with the base material 31. Its hardness is 900 HV to 1000 HV. Also, a porous nitride compound layer 32b having a low density and having a large number of pores therein is formed on the surface side. Its hardness is 500 HV to 700 HV.
The dense layer 32a and the porous layer 32b constitute a nitride film in the present embodiment.

The intermediate layer 33 is a metal layer made of chromium, and is formed on the surface of the porous layer 32b by a sputtering coating method.
This intermediate layer 33 has a hardness of 700 HV to 800 HV, is harder than the porous layer 32b (500 HV to 700 HV) of the nitride layer 32, and softer than a DLC layer 35 (1500 HV to 3000 HV) described later. Forming. That is, the intermediate layer 33 is compatible with any of the nitride layer 32 and the DLC layer 35 and has a function of improving the adhesion between the porous layer 32 b and the DLC layer 35. That is, the intermediate layer 33 forms an inclined layer that connects a hardness gradient between the base material 31 and the nitride film layer 32 formed on the surface thereof, and a DLC layer 35 described later. It is provided to relieve internal residual stress due to direct lamination. Moreover, as a result, it is for improving the adhesiveness of the upper layer (in this embodiment, DLC layer 35) with respect to the lower layer (in this embodiment, the base material 31).

The DLC layer 35 is formed on the intermediate layer 33, that is, on the outermost surface of the needle bar holder 30.
The DLC layer 35 in the present embodiment is formed by ionized vapor deposition. In other words, in a vacuum, plasma is generated using high-temperature arc discharge with a hot filament, and a negative (-) bias is applied using the base material 31 side as an electrode. This method is characterized in that the film thickness can be controlled on the nano order, and a film having a relatively high hardness can be obtained. Further, when the DLC layer 35 is formed by the ionized vapor deposition method, there is no hydrogen (H) remaining in the film as compared with the high-frequency plasma CVD method, which is preferable because it does not easily cause brittleness. In the present embodiment, as described above, the intermediate layer 33 made of chromium is interposed on the nitride layer 32, and the DLC layer 35 is further stacked thereon. Therefore, compared with the case where the DLC layer 35 is formed directly on the base material 31 or the nitride layer 32, the difference in hardness with the member in contact with the DLC layer 35 is small, so that the residual stress between each layer is greatly relieved. ing. That is, the DLC layer 35 stably grown with high adhesion is formed to be sufficiently thick.
The DLC layer 35 does not have a crystal grain boundary due to its amorphous structure, and has a very smooth surface compared to a hard thin film having a polycrystalline structure such as titanium nitride.
The DLC layer 35 has both the characteristics of diamond as a shared crystal and graphite having a laminated structure. That is, the DLC layer 35 has a hardness equivalent to that of diamond (1500 HV to 3000 HV) and has the same ease of peeling of the surface as graphite, that is, slipperiness and smoothness.
Note that the DLC layer may contain metal, particularly Cr or W. Thereby, compatibility with an intermediate | middle layer can be made more favorable and the mutual adhesiveness can be improved.
Each sewing machine component of the clutch mechanism 60 also includes the same base material, nitride layer, intermediate layer, and DLC layer.
In this embodiment, liquid lubricant such as lubricating oil is not used, but grease is applied to the sliding contact surface between the needle bar 10 and the needle bar holder 30 in order to make the sliding property at the sliding part smoother. It is used by applying.

(Operation of needle bar drive mechanism)
Next, the operation of the needle vertical movement mechanism 50 in the sewing machine 1 according to the present embodiment will be described.
First, when the sewing machine is stopped, by operating the switching mechanism 80, the holding of one of the two needle bars 10 is released.
Next, when the main shaft 52 and the eccentric weight 53 are rotated by driving the sewing machine motor, the tip of the needle bar crank 54 attached to the eccentric weight 53 is moved in the vertical direction. As the needle bar crank 54 moves, the needle bar holder 30 attached to the needle bar crank 54 and the needle bar 10 held by the needle bar holder 30 reciprocate in the axial direction (vertical direction in FIG. 1). . When the needle bar 10 is driven, a sliding portion is formed between the needle bar 10 and the needle bar holder 30.

  Here, since the DLC layer 35 is formed on the surface of the needle bar holder 30, the surface of the needle bar 10 and the DLC layer 35 of the needle bar holder 30 are in sliding contact. Since the DLC layer 35 has excellent friction and wear characteristics (tribological characteristics) due to its smooth surface, good slidability can be obtained. That is, the needle bar 10 and the needle bar holder 30 slide smoothly. Therefore, the wear resistance and durability of the sewing machine are improved.

Furthermore, according to the experiment of the present inventor, the sewing machine 1 according to the present embodiment equipped with the needle bar holder 30 having the DLC layer 35 formed on the surface can be operated at 3000 rpm and 50% actual operation rate for at least 1500 hours. It was possible.
As an actual market situation, assuming that the usage state in a garment factory is 2500 rpm and an actual operation rate of 20%, an actual operation time for one year is about 500 hours.
On the other hand, in the sewing machine 1 according to the present embodiment, the acceleration coefficient of the environmental temperature and the operation rate is 2.4 times, and therefore equivalent to 1500 hours × 2.4 = 3600 hours when converted into the actual market.
In other words, according to the sewing machine 1 according to the embodiment of the present invention, even if it is operated in a dry environment, it can be used for at least 7 years if the actual usage in the market is the above-described usage state. Become.
That is, even a dry sewing machine that operates only with grease without forcibly supplying lubricating oil is equivalent to or better than conventional sewing machines that forcibly supplied lubricating oil to sliding parts. Wear resistance characteristics will be obtained.

(Effect of embodiment)
As described above, according to the sewing machine 1 according to the present embodiment, even when the base material 31 made of low carbon steel, low carbon alloy steel and alloy steel is used for the needle bar holder 30 which is a thin-walled member, A DLC layer by DLC coating can be formed on the surface of the base material 31. Therefore, the hardness of the surface of the needle bar holder 30 can be greatly improved, and the friction coefficient of the surface can be greatly reduced. Therefore, the lubricity of the sliding surface can be greatly improved.
Thereby, even in a dry environment where forced oiling is not performed, it is possible to achieve (secure) durability that enables use for at least 7 years, which is equal to or higher than that of a conventional sewing machine that has performed forced oiling.
Moreover, a DLC film can be formed on the surface of the said steel material by destroying the dimensional accuracy of the steel material which has not performed the hardening process by heating by forming a DLC film by the method mentioned above.

The intermediate layer 33 is not limited to a single layer, and may be two layers or three or more layers. That is, in this embodiment, only one intermediate layer 33 made of chromium is used. For example, as shown in FIG. 7, the intermediate layer 33 made of chromium is formed on the porous layer 32b, and the intermediate layer is formed. An intermediate layer 34 (W layer: 900 HV to 1000 HV) made of tungsten (W) may be further formed on 33. Such an intermediate layer 34 is also formed by a sputtering coating method.
In this case, the intermediate layer 34 is preferably a layer made of a substance whose hardness is located between the porous layer 32b and the DLC layer 35, and is preferably laminated so that the hardness increases as it becomes an upper layer. . In this way, by forming the intermediate layer as two layers, intermediate layers 33 and 34 composed of two metal layers are formed between the porous layer 32b and the DLC layer 35, and the inclination is caused by the metal having a close hardness. A layer can be formed. Therefore, it is familiar with the upper and lower layers, and the adhesion between the upper and lower layers can be further improved. That is, the DLC layer 35 formed on the outermost surface can be maintained for a longer time. Therefore, the durability of the sewing machine 1 can be improved.

  Further, the DLC layer 35 formed on the outermost surface may be a WC / C (tungsten carbide / carbon) layer 36 as shown in FIG. In such a configuration, since the hardness of the WC / C layer 36 is 1000 HV to 1500 HV, it is closer to the hardness of the intermediate layer 33 (700 HV to 800 HV) than the DLC layer 35, and adhesion and chemical stability with the intermediate layer 33. Good and familiar. Therefore, a stable cured film with high adhesion can be formed.

  In this embodiment, the sliding portion between the needle bar 10 and the needle bar holder 30 is taken as an example of the sliding part, and the nitride layer 32, the intermediate layer 33, and the DLC layer 35 are formed on the surface of the needle bar holder 30. However, the portion to which the present invention is applied is not limited to the needle bar holder 30. In other words, the surface of the needle bar 10 may be subjected to a hardening process, or the sliding contact surface between the shaft and the bearing, or the two members such as the inner hook and the outer hook may be relatively in sliding contact with each other. Applicable.

It is a front view which shows the needle bar drive mechanism in this embodiment. It is a side view which shows the needle bar drive mechanism in this embodiment. It is a perspective view which shows the needle bar holding in this embodiment. It is a conceptual diagram which shows the laminated structure of the surface vicinity of the needle bar holding formed by the surface treatment in this embodiment. It is an enlarged photograph which shows the laminated structure of the surface vicinity of the needle bar holding formed by the surface treatment in this embodiment. It is an enlarged photograph which shows the surface vicinity structure | tissue of the base material of the needle bar holding in this embodiment. It is a conceptual diagram which shows the state which formed the DLC layer in the surface of the nitride layer of the needle bar holder in this embodiment through the intermediate | middle layer which consists of two layers, Cr layer and W layer. It is a conceptual diagram which shows the state which formed the WC / C layer in the outermost surface through the intermediate | middle layer which consists of Cr on the surface of the nitride layer of the needle bar holding in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sewing machine 10 Needle bar 30 Needle bar holding 31 Base material 32 Nitride layer (nitride compound layer)
32a Dense layer 32b Porous layer 33 Intermediate layer (Cr)
34 Middle layer (W)
35 DLC layer 36 WC / C layer 50 Needle up-and-down movement mechanism 52 Main shaft 53 Eccentric weight 54 Needle bar crank 55 Needle bar support frame 60 Clutch mechanism 61 Clutch member 62 Follow link 63 Press spring 64 Latch claw 65 Press spring 80 Switching mechanism

Claims (6)

In a sewing machine part in which the surface of a base material made of steel that has not been hardened by heating has been subjected to wear resistance, a dense layer that is bonded to the base material is bonded to the surface of the base material, and is bonded to the dense layer. Forming a nitride film having a porous layer, and further forming a DLC film with an intermediate layer interposed therebetween,
The sewing machine component according to claim 1, wherein the intermediate layer has a hardness region located between the nitride film and the DLC film.   The sewing machine component according to claim 1, wherein the DLC film is made of one type of DLC film containing a metal.   The sewing machine component according to claim 2, wherein the metal contained in the DLC film is Cr or W. In a sewing machine part in which the surface of a base material made of steel that has not been hardened by heating has been subjected to wear resistance, a dense layer that is bonded to the base material is bonded to the surface of the base material, and is bonded to the dense layer. Forming a nitride film having a porous layer to be formed, and further forming an WC / C film with an intermediate layer interposed therebetween,
The sewing machine component according to claim 1, wherein the intermediate layer has a hardness region located between the nitride film and the WC / C coating.   The sewing machine part according to any one of claims 1 to 4, wherein the intermediate layer is made of Cr or W.   The steel material not subjected to the hardening treatment by heating is a low carbon steel, a low carbon alloy steel or an alloy steel which has not been subjected to any of carburizing quenching and tempering or quenching and tempering treatment. The sewing machine part according to claim 5.