JPH0320452A - Method for controlling carburizing - Google Patents

Abstract

PURPOSE:To regulate a carburized layer on a carburizing control surface to the desired depth by sticking a carburizing control material allowing activated carbon to pass by a fixed quantity in a carburizing atmosphere to the carburizing control surface of a material to be carburized and carrying out carburizing treatment for the prescribed time. CONSTITUTION:A main agent 8 (e.g. B2O3) having a carburizing-preventing function is uniformly diffused into an auxiliary agent 9 (e.g. ethylene-ethyl acetate copolymer resin and xylene), by which a tape 16 having a thickness capable of allowing a fixed quantity of activated carbon to permeate in the prescribed atmosphere is prepared. This tape 16 is stuck, by heating, e.g. to the bottom Wa of a gear and subjected to carburizing treatment for the prescribed time in the prescribed atmosphere containing activated carbon. By this method, the carburized layer of the desired depth can be formed in the bottom Wa.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a carburization control method.

(Prior art) In general, carburizing methods include a solid carburizing method that uses powder such as charcoal, coke, bone ash, graphite, etc. as a carburizing agent, and a method in which the carburized material is placed in a molten salt containing potassium cyanide as the main component. The liquid carbonitriding method involves simultaneously carburizing and nitriding the carbon monoxide and nitrogen that are generated by inserting parts such as gears, and using natural gas, carbon monoxide, methane, and ethane.
propane. Gas carburizing methods carried out in oil vapor or alcohol are known.

To show an example of the gas carburizing method, in the hardening apparatus shown in FIG. There, it is treated with charcoal and then transported out via quenching oil 1115, steam cleaning device 6, and low-temperature tempering device 7.

In this gas carburizing method, the part W is heated in a carburizing furnace 4 under heating control using a heat pattern as shown in FIG. Carburized to a predetermined depth.

However, in such carburizing control, although the carburizing depth can be adjusted to a certain extent by adjusting the carburizing gas concentration, furnace temperature, and processing time in the carburizing furnace 4, the surface of the part W may not be uniformly coated. A carburized layer is formed, and depending on the shape of the part W, it is not possible to form a carburized layer that is partially or with a different carburized depth.

Here, for example, in a gear, if the carburization depth of the tooth bottom is made sufficiently shallow compared to the tooth surface which has been adjusted to an appropriate carburization depth, a high-strength gear with strong fatigue and impact resistance can be obtained. Are known.

Conventionally, for example, the carburized layer on the surface of the part after carburizing is treated with a grinder, and then the carburized depth is partially corrected by quenching, but the grinding/processing requires a lot of time and effort. This causes problems in mass production.

Furthermore, a liquid or paste-like carburization inhibitor (carburizing preventive agent) is used, and after applying this to the part that is not desired to be carburized, it is passed through the carburizing furnace 4, for example.
With liquid or paste carburization inhibitors, there is a problem of dripping depending on the shape of the object to be carburized during coating, and it is difficult to configure the coating equipment, and in particular, it is difficult to properly adjust the thickness of the coating film. There is a problem that the depth cannot be adjusted with high precision.

Incidentally, a paste-like carburization inhibitor can be made non-carburized with a thickness of 30 μm or more, for example, but if you want to make the carburized layer half that thick, the thickness of the carburization inhibitor should be, for example, 10 μm or more.
Even if an attempt is made to uniformly apply the coating to a thickness of 15 μm, it is almost impossible to do so, even if the coating is applied using a coating gage, due to the difference in thickness between the area immediately after the start of coating and the area at the end of the coating.

Furthermore, as the latest technology related to these problems, Japanese Patent Application Laid-Open No. 51-41647 (Semi-carburized product for carburized bearings)
, JP-A-51-50240 (Method for isolating partial surface areas in thermochemical treatment of metals), JP-A-52-7872
1 (partial carburizing method for parts) is proposed.

The invention disclosed in JP-A No. 51-41647 is to carburize the carburized layer to an appropriate level by locally thinly plating the bearing or applying a coating layer such as mottled thermal spraying and then carburizing the bearing.
This means that it can be made into a semi-charcoal-proof state.

In addition, the invention of JP-A-51-50240 discloses that a self-adhesive tape containing metal powder is locally applied to natural or synthetic fibers in metal thermochemical treatment (bimetallic diffusion infiltration method) using a salt bath method or a powder method. The coating prevents activated carbon from diffusing and penetrating locally.

Furthermore, the invention of JP-A-52-78721 relates to a method of applying an anti-carburizing agent to a desired position, and uses a masking tape, which is often used in painting, to apply an anti-carburizing agent to areas that do not need to be coated with a carburizing agent. By pre-coating C and then applying the anti-carburizing agent, the anti-carburizing agent can be easily and accurately applied.

(Problems to be Solved by the Invention) However, in the invention of JP-A-51-41647, even though the plating is thin, carburizing gas is completely blocked, resulting in complete carburization rather than semi-carburization. In the case of spotty thermal spraying, uneven carburization occurs, which is a practical problem.

Further, the invention of JP-A-51-50240 completely prevents carbon penetration, so the carburization depth cannot be freely adjusted. The same applies to the invention of JP-A-52-78721.

Therefore, an object of the present invention is to provide a carburizing control method that can be applied to various carburizing treatment methods and that can adjust the carburizing depth to a desired value.

[Structure of the invention]

(Means for Solving the Problems) A carburization control method of the present invention for solving the above problems involves adjusting a carburization control material that allows a certain amount of activated carbon to pass through in a carburizing atmosphere. It is characterized in that the depth of the carburized layer on the carburized control surface is set to a desired value by pasting it on the carburizing control surface of the material to be carburized and carburizing it for a predetermined period of time in a carburizing atmosphere containing activated carbon. shall be.

(Function) In the carburization control method of the present invention, a carburizing gas medium is attached to the carburizing control surface of the carburized material, and carburizing is performed for a predetermined time in a carburizing atmosphere containing activated carbon, so that the carburizing atmosphere is kept constant. By this and by setting the treatment time to a predetermined time, it is possible to control the carburization depth to a desired value.

As a carburization control material that allows a certain amount of activated carbon to pass through the carburizing atmosphere, the following materials can be used.

■ As shown in Figure 1(a)°, a sheet with a thickness that allows a certain amount of activated carbon to pass through in a certain atmosphere by uniformly dispersing the main agent (carburizing agent) 8 having a carburizing function into the auxiliary agent 9. or formed into a tape shape. Examples of auxiliary agents include plasticizers, fillers, deterioration prevention agents, and polymers for imparting self-adhesiveness and heat-fusibility.

(2) As shown in FIG. 1(b), a glass carrier 10 is impregnated with the base material 8.

■ As shown in FIG. 1(C), a fibrous substance is used as the main ingredient 8.

(2) As shown in FIG. 1(d), an adhesive layer 11 is provided on the surface.

(2) As shown in FIG. 1(e), a metal tape 12 with countless slits 13 of a precise width cut.

(2) As shown in diagram (f), a metal tape 12 has countless holes 14 of precise minute diameter uniformly drilled therein.

(Example) Examples of the present invention will be described below.

First, an example of adjusting the carburization control material will be described.

First, boron oxide B203 was used as a main agent with carburizing function, and the following composition was used: B203 (20 μm product) 20.0 parts Ethylene-vinyl acetate copolymer resin 30.0 parts Xylene 50.0 parts Sheet-shaped carburized control materials with film thicknesses of 40 μm, 180 μm, and 120 μm were obtained.

This carburized control material melts at about 150° C. and has thermal adhesive properties.

Therefore, this carburized control material was applied to SCM420 test steel material at a temperature of 180°C, a crimping time of 6 seconds, and a pressure of 4 kg/
After crimping with CD, carburization was performed in a gas carburizing furnace under conditions of 950° C. for 8 hours, and the following results were obtained.

Sheet film thickness Effective hardened layer depth No sheet
0.80mm 40um 0.40em80μm
0.31+n120μm
0.18mm effective hardened layer depth (HV550 or higher) is S
Uniform and reproducible for CM420.

As can be understood from the above results, according to the carburized control material of this example, the effective hardened layer depth can be controlled with high accuracy by adjusting its thickness.

Other resins that can be used to provide self-fusion properties include copolyesters such as polyethylene terephthalate, cobolyamides such as polyε-cabrolactam and polyhexamethylene adivamide, and cobolymers of the above-mentioned copolyesters and cobolyamides.

Second, KP-12<30 manufactured by Nippon Carbide Co., Ltd. was used as the acrylic adhesive, and the following formulation was used: B203
20.0 parts acrylic adhesive 30
．． Using 50.0 parts of 0 parts xylene, sheet-like compositions of various film thicknesses were obtained, which were integrated on release paper to obtain sheet-like carburization control materials.

Since the carburization control material of this example has self-adhesive properties, it can be formed into a tape shape, for example, and attached to the carburization control material while being cut as appropriate. In this case, a release paper remains on one side after the carburization prevention material is applied, but this is not a problem because it is incinerated in the atmosphere of the carburization process. Further, the release paper may be applied not only to one side but also to both sides, and the one from one side may be removed before use.

Other materials that can be used to provide self-adhesive properties include acrylic resins, mixtures of synthetic rubber and thermosetting phenolic resins, polyisobutylene, polyethylene vinyl acetate copolymers,
A polyurethane adhesive or the like can be used.

Thirdly, after forming the carburized control material into a sheet, a 15 μm thick film was applied to the surface.
The sheet is laminated with a thick polyethylene-vinyl acetate copolymer to prevent deterioration of the sheet.

In this example, since moisture absorption in the atmosphere can be prevented, deterioration of boron oxide can be prevented.

Fourthly, a film of polyethylene terephthalate, polyethylene, vinyl chloride, or vinylidene chloride can be used in place of the release paper to prevent deterioration and to function as a support carrier.

In this example, the release paper can be peeled off and the carburization control material can be pasted on the material to be carburized, or the supporting carrier/closing film can be thermally melted and bonded.

Fifth, the following formulation H2 BO3 (20 am) 40.0 parts Methyl cellulose (product name: Ha's. Shin-Etsu Chemical) 1 0
A tape-shaped carburization control material can be obtained by impregnating, for example, a polyester nonwoven fabric E5060 manufactured by Asahi Kasei Co., Ltd. with this mixture.

By using various resins instead of methylcellulose, it is also possible to impart heat-fusibility or self-adhesive properties.

Sixthly, 19.0 parts of the following compound B203 and 81.0 parts of an ABS resin pellet were heated, melted and spread, and then made into pellets again to obtain a carburized control material for an injection mold.

This carburized control material can be adapted to injection molding machines.

The control material to be carburized is preferably treated with a primer such as silicone primer ThreeBond 5261 manufactured by ThreeBond. In addition to ABS resin, injection molding resins include polyamide (nylon), polyolefin (PE-E
VA, polypropylene), polyester, copolymer (A
BS, SBS) etc. can be used.

Seventh, the following formulation: Na2 B4 07 19.0 parts Methyl methacrylate polymer 22.7 g Xylene
38.3 parts methylene chloride 2
0.0 part is formed into a rectangular shape with a predetermined thickness on a release paper using a gravure roll to obtain a carburized control material consisting of plate-shaped pellets.

This carburization control material can be applied to the surface of the material to be carburized by molding using a mold.

Eighthly, a tape-shaped carburized control material can be obtained by forming slits 13 or holes 14 in a metal tape 12 such as copper.

The thickness of the metal tape is about 0.05 to 0.6 mm, the slit width is 0.001 to 0.1, and the slit interval is 0.01 to 0.
．． 2. Hole diameter 0.001~0.1, Hole spacing 0.01~0.
By adjusting the width or diameter and interval of 2 mm, desired carburization control can be performed. An adhesive layer may be appropriately provided on the surface of the metal tape, and the metal tape may be attached to the surface of the control material to be carburized.

The slits 13 and holes 14 can be formed by laser machining, electrical discharge machining, or press working.

That is, in laser processing, continuous processing can be performed by pulse-controlling a laser beam focused into a slit or hole shape and moving the tape 12 in one direction with respect to this laser beam.

In electrical discharge machining, for example, by preparing a mold for slits and holes with a length of 10 to 30 cm, and after completing electrical discharge machining of one unit length, feeding the tape 12 intermittently every 10 to 30 cm, Continuous processing is possible.

Furthermore, in press working, electrical discharge machining etc.
0cII 1st unit length carburizing system. Using a precisely manufactured mold to process the wood, we can perform press processing for each unit length. It is also possible to use rotating rollers for press working.

For carburized control materials using these metal tapes, the thickness of the adhesive layer is adjusted to about 10 to 100 um, and the slit 1
If the carburizing gas that enters through the holes 14 and 3 is dispersed between the adhesive layers and then applied to the component surface, the depth of the carburized layer on the component surface can be made more uniform.

Next, a method of attaching the carburization control material constructed as described above to a material to be carburized will be explained.

The apparatus shown in FIG. 2(a) uses a carburizing control material having heat-adhesive properties, and attaches the carburizing control material of a predetermined thickness to the tooth bottom of a gear W as a material to be carburized.

That is, the apparatus of this example includes a motor M1 that pitch-feeds the gear W, a motor M2 that transports the tape TPI between reels R1R2 on the upper part of the gear W that is pitch-fed by the motor M1, and a motor M2 that transports the tape TPI between the reels R1R2 and A pushing jig 1 arranged to be movable up and down in alignment with the bottom of the tooth of the gear W.
5.

The tape TPI is constructed by attaching a carburization control material 16 to a release paper 17.

The pushing jig 15 is heated with a heater 19 by a heater controller 18 connected to a temperature sensor TC. Also, the pressure cylinder 20 causes the tape TP to
I is configured to press I against the tooth root.

In the pasting device having the above configuration, when the pressure cylinder 20 is driven downward, the pushing jig 15 presses the carburization control material 16 against the bottom of the gear W through the release paper 17, and the heater 1
At the temperature obtained in step 9, the carburized control material 16 is pressed onto the tooth bottom Wa as shown in FIG. 2(b).

Thereafter, when the pushing jig 15 is raised by the pressure cylinder 20, the female pattern 17 returns to the state shown in the figure, and the carburization control material 1
6 is cut, and then the gear W is pitch-fed by the pitch-feed motor M1.

Therefore, according to the pasting device of this example, the carburization control material 16 can be efficiently pasted to the tooth bottom Wa, as shown in FIG. 2(b).

As described above, according to the pasting device of this example, by pasting the carburized control material of any thickness at any position, the depth of the carburized layer at any position of the gear W can be controlled to any desired value. I can do it.

The pasting device shown in FIG. 4 uses a tape TP2 in which a self-adhesive carburized control material 21 is attached to a release paper 17, and attaches the carburized control material 21 to the bottom of a gear W while cutting it with a cutter 22. This is an example of pasting.

In this example, since the carburization control material 21 is pasted while being cut by the cutter 22, the heater 19 shown in FIG. 2(a) is not necessary.

In the pasting device shown in FIG. 5(a), a tape TP3 is constructed by pasting a carburized control material 16 with heat fusion properties to a release paper 17, and this tape TP3 is punched out using a jig 23 as shown in FIG. (
This is an example in which the punch is punched out as shown in b), transferred to the tooth bottom of the gear W by the robot 24, and then crimped with the heated pushing jig 15.

The pasting device shown in FIG. 6 is an example in which a tape-shaped carburization control material TP4 that does not have heat-sealability or adhesiveness is pasted using an adhesive.

That is, in this example, before the tape TP4 punched out by the punching jig 23 is transferred by the robot 24, the amount of application is controlled by the dispenser 25 to the tooth bottom of the gear W, and the nozzle is driven up and down by the cylinder 26. Apply adhesive in step 27.

Therefore, in this example, the carburized control material (TP4) punched out with the punching jig 23 can be attached to the tooth bottom to which the adhesive has been applied.

The pasting device shown in FIG. 7(a) aligns pellet-shaped carburizing control material 28, which has been preformed to match the shape of the carburizing control surface of gear W, with two parts feeders, and transports it with a robot 24. However, this is an example in which it is attached to the tooth bottom coated with adhesive in the same way as shown in FIG. Figure 7 (
b) shows an enlarged view of the pasted state.

The carburization control material 28 in the form of pellets shown in this example is made thicker by diluting the carburizing main agent so as to have a predetermined strength so as to be compatible with the parts feeder 29.

The pasting device shown in FIG. 8 is an example of an ejection type.

That is, for example, male and female molds 30.3 are used for the bevel gear W.
1, a female mold 30 is provided with a resin injection port 32, and a male mold 31 is provided with a resin escape port 33.

However, in the injection molding of this example, the molding thickness is 30 to 200.
The inner surface of the female mold 30 is made of an elastic member so as to absorb the error of the gear W in order to adjust the positional deviation.

In this example, since the injection mold is used, high precision machining is possible and the machining speed is high.

In this example, the bevel gear W is injection molded all at once, but to improve accuracy, injection molding may be performed one or more teeth at a time. Further, by constructing a gear-shaped mold so that it can rotate freely, continuous injection molding may be performed while rotating the gear W.

The present invention is not limited to the above embodiments, but can be implemented in any appropriate manner by making appropriate design changes.

〔Effect of the invention〕

As described above, since the present invention is a carburizing control method as described in the claims, it can be applied to various carburizing treatment methods, the carburizing depth can be controlled to a desired value, and the fatigue strength is high.
It is possible to manufacture products with excellent impact resistance.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of the carburization control material used in the present invention, Fig. 2(a) is an explanatory diagram showing an example of the application device, and Fig. 2(b) is an explanatory diagram showing an example of the carburization control material applied. An enlarged explanatory diagram, FIG. 3(a). (b) and (c) are explanatory diagrams showing the cross-sectional structure of a carburized gear, FIG. 4 is an explanatory diagram showing a configuration example of another pasting device, and FIG. FIG. 5(b) is an explanatory diagram showing a configuration example, FIG. 5(b) is an explanatory diagram showing a tape punching method, FIG. 6 is an explanatory diagram showing another configuration example of the pasting device, and FIG. 7(a) is an explanatory diagram showing a further configuration example. An explanatory diagram showing an example of the configuration of another pasting device, FIG. 7(b) is an explanatory diagram showing an enlarged pasting method for pelletized carburized control material, and FIG. 8 shows a mold structure used for injection molding. FIG. 9 is an explanatory diagram of the gas carburizing method, and FIG. 10 is an explanatory diagram of the heat pattern in the gas carburizing method. 8... Carburizing agent 9... Auxiliary agent 10... Glassy carrier 11... Adhesive layer 12... Metal tape 13... Slit 14... Hole 1 Figure (a) 1st Diagram (b) @1 Diagram (c) Chest 1 diagram (d)

Claims (4)

[Claims] (1) Adjust a carburization control material that allows a certain amount of activated carbon to pass through in a carburizing atmosphere, and attach the carburization control material to the carburization control surface of the material to be carburized to create a predetermined carburization control material containing activated carbon. A carburization control method, characterized in that the depth of the carburized layer on the carburization control surface is set to a desired value by carrying out carburization treatment in an atmosphere for a predetermined period of time. (2) The carburization control method according to claim 1, wherein the carburization control material has self-adhesion. (3) The carburization control method according to claim 1, wherein the carburization control material is formed into a tape shape. (4) The carburization control method according to claim 1, wherein the carburization control material is formed into a shape that matches the surface shape of the carburization control surface.