JPH0344421A - Quenching apparatus for correcting outside diameter of annular body - Google Patents

Abstract

PURPOSE:To prevent deterioration of dimensional accuracy, circularity, etc., of an annular body by expansion caused by martensite transformation by setting annular body into an outside diameter correcting quenching apparatus of specific construction and cooling it at the specific temp. range at the time of quenching the annular body of the steel-made bearing case, etc. CONSTITUTION:At the time of quenching the annular steel product of steel-made bearing case, etc., in order to prevent the development of error in the outside diameter size, circularity, etc., of the bearing case by the expansion caused by the martensite transformation, after heating the annular body 1 for bearing case up to quenching temp., the annular bodies 1, for which the primary cooling is already completed, are superposed successively in a cylindrical mold A, the inside diameter (d) of which is equal to the outside diameter size of bearing case 1. secondary quenching liquid 5 is injected to the annular bodies 1 from injection nozzles 6 while pressing the superposed annular bodies with a pusher 4 providing a hydraulic piston 8 from upper part and these bodies are cooled while passing through the martensite transformation point Ms. As the annular bodies 1 are in the cylindrical mold A, the variation of shape, size, circularity, etc., with the expansion of the body 1 at the time of passing through Ms point are not developed and the bearing case 1 excellent in accuracy of dimension and shape with the normal outside diameter (d) can be manufactured with good product yield.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to products where the outer diameter of the product is particularly important when hardening a steel annular body such as a M-made bearing case to produce a final product. A hardening device suitable for hardening, more specifically, a hardening device that can correct errors in the annular body that tends to undergo martensitic transformation expansion and cause relatively large errors in outer diameter dimensions, roundness, cylindricity, warpage, etc. The present invention relates to a device for correcting the external shape of an annular body, which is as small as possible, has high dimensional accuracy, has high production efficiency, and can be manufactured at low cost.

(Prior art) Generally, quenching of a steel annular body involves martensitic transformation expansion, which causes dimensional errors in the inner and outer diameters and quenching distortion (circularity and cylindricity are distorted and warping occurs, respectively). becomes a problem.

When high precision is required for product dimensions, the machining allowance after quenching is either nonexistent or minimal, so dimensional errors and quenching distortions due to quenching become extremely important problems. Taking the case of the outer race as an example, quenching with less deviation in external dimensions, roundness, cylindricity, etc. is strongly desired.

In view of the above, in order to correct the outer diameter expansion during quenching, including martensitic transformation, to within a predetermined dimension, the applicant pressurizes and restrains the outer diameter of the product with a chuck, and creates a gap between the expanded plastic material and the same chuck. In 1984, a device was developed to create a strong pressure welding relationship between the two, suppress further expansion, and harden while controlling the dimensions.
13405, 58-31369 and 63-6204
Provided by.

(Problems to be Solved by the Invention) These methods have far reduced outer diameter dimensions and quenching distortions compared to quenching without outer diameter constraint, and exhibit a certain degree of effectiveness, but it is commonly pointed out that The problem is that the outer diameter of the annular body is restrained discontinuously in the circumferential direction by the chuck itself having its own dimensions or by the restraining claws that are combined with the chuck and can move forward and backward in the radial direction. As shown in Figure 4 (B), the outer diameter shape of the body has an uneven shape (petal-like) corresponding to the number of restraining claws (chuck or), and this becomes a factor that inhibits the accuracy of outer diameter grinding of both layers. Second, the chuck or restraining jaw must hold the annular body stationary in one immovable horizontal processing area after quenching is completed, which means that production efficiency is reduced due to batch processing. Worse still, and thirdly, the high material costs due to batch processing and the application of multiple chucks or restraining jaws, combined with the high cost of production, inevitably lead to an increase in production costs.

The present invention aims to solve the above-mentioned problems all at once.

(Means for Solving the Problems) The general solution concept of the present invention to achieve the above object is to stop restraining the annular body to be hardened with discontinuous chucks or restraining claws in the circumferential direction, and to create a continuous circumferential surface. It is also possible to carry out the hardening of the individual toroids intermittently in a vertically moving surface area of a length which is an alternative to the hardening of the individual annular bodies in one stationary horizontal processing area, and to carry out this descent over not one but several annular bodies. Massively moving the bodies in a stacked state, and intermittent vertical movement of the annular body using a pusher, including ejection of the annular body that has been quenched under external diameter restraint... However, the means for realizing this will be explained below using diagrams corresponding to examples. Figure 1 shows the temperature -
Length change diagram; Figure 2 is a vertical sectional view showing an embodiment of the device of the present invention; Figure 3 is an end view taken along the line ■-■ in Figure 2; Figure 4 (A).
1 is a schematic diagram showing the outer diameter shape of the quenched bottom layer of an annular body when the device of the present invention is used, and (B) is a schematic diagram showing the outer diameter shape of the quenched bottom layer of the annular body when Utility Model Publication No. 63-6204 is used. It is.

As shown in the figure, the present invention is an apparatus for continuously quenching an annular body accompanied by martensitic transformation expansion while correcting the outer diameter dimension after quenching to a predetermined value. 1 having a cylindrical cavity 2 having an inner diameter d that matches the above and a height h capable of vertically stacking a plurality of annular bodies 1 after primary cooling.
three cylindrical supports, a pusher 4 that intermittently presses down from above the uppermost one of a plurality of annular bodies 1 stacked in the cylindrical cavity 2; The primary cooled annular body 1 is placed in the cylindrical cavity 2 and carried into the cylindrical cavity 2.
A secondary cooling injection nozzle 6 for applying a secondary cooling liquid 5 to..., an annular body 1, which is sequentially carried into the cylindrical cavity 2 and stacked vertically.・ completes its martensitic transformation and expansion while intermittently descending inside the cylindrical cavity 2 while being subjected to secondary cooling by the secondary cooling liquid 5 from the injection nozzle 6 . The outer circumferential surface 10 of the expanded annular body is constrained to a predetermined outer diameter by the inner circumferential surface 20 of the cylindrical cavity 2, and the annular body after the transformation and expansion is completed.
The present invention relates to an apparatus for straightening and hardening an annular body in its outer diameter, characterized in that the annular body is sequentially ejected out of the cylindrical mold 3 by intermittent compression by the pusher 4. In the figure, 7 is a mold holder, 8 is a hydraulic piston of the pusher 4, and 9 is a lid.

Generally, when quenching rust, steel is treated as shown in Figure 1.
Causes dimensional changes such as expansion and contraction. In the figure, the vertical axis is the dimension, the horizontal axis is the temperature, and Ms indicates the martensitic transformation point.

In the present invention, the annular body heated to a predetermined quenching temperature is heated to a cooling oil tank (not shown) in a free state until it reaches the MS point.
The next hardening is carried out (a→b in the figure). At this time, the dimensions of the annular body 1 are the smallest due to contraction, and after that, the annular body 1 is in a state where it is about to start expanding due to martensitic transformation. is inserted into the cylindrical cavity 2 of the cylindrical mold 3 having a predetermined inner diameter dimension d in a constant short cycle, and the annular body 1 is sequentially pushed into the cylindrical cavity 2, (bad in the figure), the cylindrical cavity inner surface 20 and the expanded plastic material, that is, the outer circumferential surface 10 of the annular body are brought into strong pressure contact using the martensitic transformation expansion to increase the accuracy of the outer diameter dimension and to sinter. This method minimizes input distortion and performs hardening with high production efficiency.

(Function) The implementation procedure and function of the device of the present invention will be described. The annular body (not shown) heated to a predetermined quenching temperature is stably cooled to a temperature near the Ms point in a primary quenching oil tank (not shown). Therefore, the quenching oil for primary oil cooling has high temperature resistance (approximately 150 to 200℃
), and in order to prevent fluctuations in cooling performance due to oxidation and polymerization, the primary quenching oil tank is equipped with N2
Prevent contact with air with inert gas such as gas. M
The annular body 1, which has been primarily oil-cooled to a temperature near point S, is then immediately transported to the entrance of the cylindrical cavity 2 of the cylindrical mold 3 by means of a conveying means (not shown). It is pushed down by a pusher 4 coupled to a hydraulic cylinder 6 installed coaxially and inserted into the cylindrical cavity 2. The cylindrical mold 3 is made of a material with high heat resistance, wear resistance, and rigidity, and the entrance part 21 of the cylindrical cavity 2 into which the annular body 1 is inserted is
It has a gentle taper in the shape of an upper wall to facilitate insertion.

The 22nd part of the cylindrical cavity 2 is straight, and its inner diameter is d.
The setting is such that there is a slight frictional resistance between the annular body 1 and the annular body 1, and the annular body 1 is finished to a target outer diameter after being hardened (after being discharged from the cylindrical mold 3). Cylindrical type 3
The annular body 1 inserted therein is uniformly cooled by the secondary cooling liquid 5 supplied in a shower form from the secondary cooling injection nozzle 6 at the upper part of the cylindrical mold 3.

In addition, if it is desired to cool the annular body 1 from the outer diameter side, it is possible to provide a spiral or spline-shaped groove (not shown) on the inner surface of the cylindrical cavity 2 and supply liquid coolant from the upper part. .

As described above, by repeating the process of primary oil cooling to the vicinity of points M and s and then insertion into the cylindrical mold in a constant short cycle, the annular body 1 is moved from the top to the bottom of the cylindrical mold 3. The annular bodies 1 are pushed in sequentially, and the martensitic transformation is completed while the annular bodies 1 move vertically from the top to the bottom of the cylindrical mold 3. Utilizing the expansion plasticity at this time, hardening is performed while restraining the outer circumferential surface 10 of the annular body 1 with the inner surface 20 of the cylindrical cavity, thereby reducing errors in the outer diameter dimension, quenching distortion (roundness, Cylindricity, warpage, etc.) can be corrected to a minimum, and hardening can be performed with high dimensional accuracy and high productivity. In addition, the stacked annular bodies 1 . . . have mutual thickness and width dimension restrictions, so that width warpage is also reduced.

An example in which an annular body of high carbon chromium bearing steel was continuously straightened in outer diameter and hardened will be shown below with numerical values.

(Example) Accuracy of outer diameter dimensions, etc. of annular body before and after quenching (,,) [Note] (1) In addition, the comparative example was an example of free quenching without outer diameter constraint.

(2) Quenching heating temperature and primary oil cooling method of the annular body; Quenching heating temperature = 830℃ Quenching oil: Idemitsu High Temp Oil T oil
Temperature: 150℃ The pulling temperature from the quenching oil (near the Ms point) is controlled by adjusting the oil retention time on the conveyor in the oil tank.

(3) Outer diameter correction hardening method for annular body; Cylindrical size: Inner diameter (straight part) φ72.18 Outer diameter
φ180 Length 200 Hydraulic cylinder: φ120 x 500ST Hydraulic unit: 140kg/aJ x 20A/wi
n rod-shaped rod-shaped object insertion coil for 8 seconds Temperature of the annular body when inserted into the cylindrical mold: 210 ± 5°C Temperature of the annular body when discharged from the cylindrical mold: 45 ± 5°C Secondary coolant: Machine oil #120 From the table above It can be seen that when using the apparatus of the present invention, the dimensional accuracy of the outer diameter after quenching is much higher than that of the comparative example, and there is less deviation in roundness and cylindricity.

In addition, the outer diameter shape (outer peripheral surface 10) of the annular body obtained in this example after quenching has a slight degree of circularity as a whole, although there is slight contraction and expansion in some parts, as shown in FIG. It turned out to be good and provides a good contrast to the previous design (b).

(Effect of the invention) With the outer diameter straightening hardening device of the present invention explained above,
The following effects can be obtained.

i) In the cooling process of the annular bodies, by sequentially inserting the annular bodies into the quench layer cylindrical mold in a short cycle in a stacked state up and down until near the Ms point, a plurality of annular bodies can be hardened to correct the outer diameter at the same time. This dramatically improves quenching productivity.

ii) By correcting the outer diameter dimension with the cylindrical mold and constraining the thickness and width dimensions with the upper and lower annular bodies, distortions such as roundness, cylindricity, and width warping of the annular body can be suppressed to a minimum, allowing hardening to accurate dimensions. . Further, due to the constrained quenching of the inner surface of the cylindrical cavity that is continuous in the circumferential direction, there is no irregularity (so-called petal-like shape) on the outer diameter of the product.

1ii) From i) and ji), it is possible to reduce the grinding allowance in the subsequent grinding process, and it is also possible to guarantee improvement in grinding productivity by shortening the grinding processing time.

[Brief explanation of drawings]

Fig. 1 is a temperature-length change diagram during quenching of steel, Fig. 2 is a longitudinal sectional view showing an embodiment of the device of the present invention, Fig. 3 is an end view taken along the line m-m in Fig. Figure 4 (A) shows the outer diameter shape of the quenched bottom layer of the annular body when the device of the present invention is used, and (B) shows the outer diameter shape of the quenched bottom layer of the annular body when Utility Model Publication No. 63-6204 is used. FIG. (Explanation of symbols) 1... Annular body (after primary quenching), 10... Annular body outer circumferential surface, 2... Cylindrical cavity, 20... Cylindrical cavity inner circumferential surface, 21...・Inlet part, 22...Straight part, 3...Cylindrical type, 4...Pusher, 5...2
Secondary quenching liquid, 6... Secondary cooling injection nozzle, 7...
Mold pedestal, 8... Hydraulic piston, 9... Lid,
d...Inner diameter dimension. h...Height, Ms...Martensite transformation point. -That's it, above-

Claims (1)

[Claims] 1. An apparatus for continuously quenching an annular body accompanied by martensitic transformation expansion while correcting the outer diameter dimension after quenching to a predetermined value, the apparatus comprising: A cylindrical mold with a cylindrical cavity having an inner diameter that matches the diameter dimension and a height that allows a plurality of annular bodies after primary quenching to be stacked vertically, and a cylindrical cavity that is stacked in the cylindrical cavity. a pusher that intermittently presses the uppermost one of the plurality of annular bodies, and a pusher that is placed above the cylindrical mold and supplies a secondary cooling liquid to the primarily cooled annular body carried into the cylindrical cavity. The annular bodies, which are sequentially carried into the cylindrical cavity and stacked vertically, are subjected to secondary cooling by the secondary cooling liquid from the injection nozzle. While descending intermittently within the cylindrical cavity, martensitic transformation expansion is completed, and at this time, the outer peripheral surface of the expanding annular body is constrained to a predetermined outer diameter by the inner peripheral surface of the cylindrical cavity, and transformation expansion occurs. An apparatus for correcting the outer diameter of an annular body, characterized in that the annular body after completion of the hardening process is sequentially ejected from the cylindrical mold by intermittent pressing by the pusher.