JPS60255292A - Joining method of roll outer layer sleeve - Google Patents

Abstract

PURPOSE:To join firmly both a core material and a roll outer layer sleeve, and to prevent crack damage from occurring in the course of use by making the thermal expansion quantity of the core material larger than the thermal expansion quantity of the sleeve, when inserting and fitting the roll outer layer sleeve into the core material, and heating and joining them. CONSTITUTION:A roll outer layer sleeve is fitted into a core material or an inside inserting material such as an inner sleeve, heated and made raised in temperature in a nonoxidative atmosphere, joint surfaces of both of them are diffused and joined, and a rolling roll is manufactured. In this case, the thermal expansion quantity of the core material is made larger than the thermal expansion quantity of the outer layer sleeve, and they are combined so that the joint surfaces are adhered tightly by a difference between the thermal expansion quantities. Especially, as for the core material, the thermal expansion quantity after an Ac1 transformation is made larger than the thermal expansion quantity of the outer layer sleeve so as to be joined at a temperature of an austenite area, and in case a usual roll material of a cast iron or cast steel compound is used for the outer layer sleeve material, as for the core material, it is desirable to use a ductile cast iron material.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to the molding of rolls used for the straight rolling of metals, etc. It relates to a method of joining to the body.

[Prior art and its problems]

When molding such a roll, it is a commonly used method to join and integrate the outer sleeve with the core material by shrink fitting, adhesion, side pressure tightening, etc.

Although these joining methods have numerous advantages both mechanically and economically, they also have the following disadvantages which are essentially unavoidable.

That is, in the shrink-fitting method, tensile shrink-fitting stress remains in the roll sleeve, and this is superimposed on rolling stress and thermal stress during rolling, often causing breakage.

Furthermore, if the shrink-fitting surface pressure is lowered to avoid this, slipping will occur and the product will become unusable.

The adhesive method is to use synthetic resin, but since resin has low thermal conductivity, heat tends to get trapped in the sleeve.
Since the resin has low heat resistance, it cannot be used in applications where heat or large rolling herks are applied.

Additionally, once the adhesive surface is damaged, unlike shrink fitting, it does not recover and cannot be used as is.

In the lateral pressure tightening method, lateral pressure is applied to the hard roll ring by tightening the nut ring at the end to secure it to the shaft, but at least a slight compressive stress is applied in the axial direction. In this respect, this method is superior to the above two methods. However, the area occupied by the inner ring and flange portion for applying side pressure on the roll surface becomes large, and the l] of the roll ring portion becomes relatively small. Further, since a reaction force of lateral pressure acts on the shirt 1-, the safety of the shaft becomes a problem.

In any case, as described above, rolls using sleeves obtained by conventional joining methods have inherent problems with the mechanism itself.

〔Problems to be solved〕

An object of the present invention is to solve the problems encountered in the conventional sleeve joining method. As a roll, even if a sleeve is used, it is firmly joined to the core material,
Furthermore, this design was made based on the fact that the most preferable and ideal form is one in which compressive stress is applied to the surface, and the sleeve is metallurgically bonded to the core material or inner sleeve material insert. We present a new method to do this.

[Solution]

Next, the joining principle of the present invention will be described.

In general, when two types of flat materials are placed on top of each other and heated in a non-oxidizing atmosphere, in most cases, the contact area expands to 1iJ1.
．． However, if they are sleeve-shaped and fitted into each other, they do not necessarily join well. In particular, if the sleeve and insert material are made of steel or cast iron and have a transformation point during the heating process, abnormal expansion and contraction will occur near this transformation point, and even if they were initially in close contact, they will heat up and then cool down. It is often observed that gaps are formed in the case of For this reason, diffusion bonding was conventionally considered to be difficult from a metallurgical perspective and was not practiced.

The inventors of the present invention have obtained the following new knowledge regarding this matter. That is, the occurrence of gaps as described above is related to the relative amount of expansion after transformation, and if the amount of expansion of the interpolation material is small, gaps will almost always occur without exception. Furthermore, if the amount of expansion of the intercalating material is large, if the temperature is set at an appropriate temperature, even if a gap is created between the two during transformation, diffusion will occur in this area and the bond will essentially be bonded. A new experimental fact has been discovered. The present invention is characterized by the combination of the material of the outer sleeve and the core material or the material of the inner sleeve such as the inner sleeve. In particular, a material whose thermal expansion after ACl transformation is larger than that of the outer sleeve is selected, and the materials are closely bonded and diffusion bonded at a temperature in the austenite range, and the bonded surfaces are tightly bonded due to the difference in relative thermal expansion between the two. It is combined so that

Materials with such characteristics include, when using cast iron or cast steel-based ordinary roll materials as the outer sleeve material,
Most conveniently, the insert is a duct quill cast iron material.

Those joined in this way will no longer peel off even if subjected to severe heat treatment such as quenching, and can sufficiently withstand the heat treatment applied to ordinary rolls.

Further, if at least one of the bonding surfaces is plated with a diffusible metal such as Ni--P alloy, stable bonding can be obtained.

In this way, in the present invention, a residual compressive stress remains in the outer sleeve due to metallurgical bonding, which is most advantageous for rolls.

〔Example〕

Next, the effects of the present invention will be explained using examples.

Example 1 An example is shown in which an outer layer sleeve having the following composition and a solid core material as an inner insertion material are joined.

Components of outer sleeve material (weight %) C: 2.7. Si: 1.0. Mn: 0.4
．． Cr: 4.5゜Mo: 6.5 Components of ductile cast iron core material (weight%) C: 3.4. Si:1.8. Mn: 0.4. P:
0.0B.

S: 0.006゜ Roll dimensions Outer layer sleeve: 310φ x 260φ x 500mm Core material (
Solid): 260φ x body length 900 mm x fitting part 500
mm Figure 1 shows the linear expansion characteristics of the outer sleeve material and the core material, where the horizontal axis is the temperature and the vertical axis is the change in length, where fa+ is the outer sleeve material and fb) is the ductile cast iron core material. It is a linear expansion characteristic. Point A is approximately 900°C, and when the temperature exceeds this temperature, the amount of expansion changes greatly.

After the outer sleeve is lightly fitted and fixed to the core material, it is housed in a steel plate seal (]) as shown in Figure 2, and air is evacuated through the degassing hole (2) to create a vacuum inside. After that, seal the deaeration hole (2) and put it in a heating furnace (in the atmosphere) and heat it.
After heating at 000°C for 8 hours and cooling in the furnace, the sealed roll was opened, the roll was taken out, and the bonding condition was examined.

The outer sleeve and core material were metallurgically bonded over the entire surface. Furthermore, when the residual stress on the surface was measured, as shown in Table 1 below, compressive stress clearly remained on the surface, confirming the effectiveness of this method.

On the other hand, for comparison, test 1 was conducted using SCM-3 material as the core material, but in this case, there was a gap at the joint and no joint was formed at all.

Example 2 This is an example in which an outer layer sleeve and an inner sleeve as an insert material are joined.

The outer sleeve had the same composition as in Example 1, and the inner sleeve also had ductile cast iron with the same composition as the core material in Example 1.

Roll dimensions Outer sleeve: 276φ x 216φX 165 mm Inner sleeve: 216φ x 28φX 165 mm
Surface treatment After Ni-P electroless plating (thickness 20 μm) is applied to the surface of the inner sleeve, the outer sleeve and inner sleeve are lightly fitted together, heated in a vacuum furnace at 1000°C for 8 hours, and then immediately taken out of the furnace and quenched. Did.

No unwelded areas or peeling due to quenching were observed in the adhesive area, and the joint was perfect.

Next, Table 1 shows the results of measuring the residual stress of the rolls of Examples 1 and 2 by the surface release method.

Note that the present invention is not limited to the above-mentioned embodiments,
It can be implemented in various ways.

9- Table 1 [Effects of the invention] (i) Since the outer sleeve and the core material (or inner sleeve) are metallurgically joined, compressive residual stress exists in the outer sleeve in the axial and circumferential directions. .

(ii) Since it is metallurgically joined, the joining force is very strong and it is safe against abnormal torque.

(iii) Safe against breakage during use.

-10～

[Brief explanation of drawings]

FIG. 1 is a diagram showing the linear expansion characteristics of the outer sleeve material and core material of Example 1, and FIG. 2 is a diagram for explaining a steel sealed can. ta+ Outer sleeve material (bl Core material (1) Seal can (2) Deaeration hole Patent applicant Hitachi Metals, Ltd. 11- Figure 1 Figure 2

Claims (1)

[Claims] 1. When diffusion bonding a rolled outer sleeve and an inner insertion material such as a core material or an inner sleeve, the material of the outer sleeve and the material of the inner insertion material are bonded at a bonding temperature of the inner insertion material. The amount of thermal expansion is greater than the amount of thermal expansion of the outer sleeve (and the combination is such that the joint surfaces are in close contact due to the difference in the relative amount of thermal expansion between the two, and the outer sleeve is fitted to the inner insertion member in advance, A method for joining roll outer layer sleeves, which comprises heating and raising the temperature in a non-oxidizing atmosphere, and utilizing the difference in the amount of thermal expansion to bring the joining surfaces into close contact at at least the joining temperature for diffusion joining. 2. AC, a patent claim characterized in that the material is selected so that the thermal expansion amount of the inner material after transformation is larger than the thermal expansion amount of the outer layer material, and the material is closely bonded and diffusion bonded at a temperature in the austenite range. A method for joining the roll outer sleeve as described in Scope 1. 3. The outer sleeve is made of a normal roll material, and the core material or inner sleeve is made of ductile cast iron material. A method for joining roll outer sleeves according to claim 1 or 2. 4. Applying an easily expandable metal to at least one of the joint surfaces of the outer sleeve and the inner insertion material. A method for joining roll outer layer sleeves according to claim 1, characterized in that the method comprises plating.