Layered bimetal composite hollow shaft rolling and expanding bidirectional laminating method

Abstract

The invention discloses a rolling and expanding bidirectional laminating method for a layered bimetal composite hollow shaft, which is characterized in that an outer shaft and an inner shaft which are made of metal materials are in interference fit to obtain an initial composite hollow shaft; then the initial composite hollow shaft is fed into a three-roller skew rolling mill, when a roller performs skew rolling on the initial composite hollow shaft, the reaming rod extends into an inner hole of the initial composite hollow shaft at the same time, and the outer diameter of the reaming rod is larger than the diameter of the inner hole of the initial composite hollow shaft; the initial composite hollow shaft is subjected to bidirectional compression in the radial direction by the roller and the reaming rod during rolling; the initial composite hollow shaft is pushed forwards in the axial direction, meanwhile, the axial relative position of the roller and the reaming rod is kept unchanged till lamination rolling of the whole composite hollow shaft is completed, and the layered bimetal composite hollow shaft is obtained; the device has the advantages that during rolling, the roller and the reaming rod simultaneously compress the composite hollow shaft inside and outside in the radial direction, and the bonding strength of the composite hollow shaft is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rolling forming of shafts, in particular to a rolling and expanding bidirectional lamination method for layered double-metal composite hollow shafts. BACKGROUND

[0002] Layered double-metal composite shafts (i.e. laminated shafts) can integrate the advantages of different materials of inner shafts and outer shafts, and achieve the best balance of performance, service life and economy at a reasonable cost through a clever composite structure. For example, a stainless steel / carbon steel laminated shaft uses high-hardness, wear-resistant and corrosion-resistant stainless steel on the working surface of the shaft (such as the shaft neck and frictional parts), and uses carbon steel with good toughness, high strength and low cost on the core, which realizes the ideal performance combination of "hard and wear-resistant on the surface and strong and impact-resistant in the core" that single material cannot simultaneously have. Traditional laminated shafts are mainly prepared by rolling process, although such technology realizes small-batch production of some parts, it still faces the bottleneck of limited forming size, and large-length-diameter-ratio metallurgical laminated shafts cannot be continuously formed at present. The three-roll cross-rolling composite process can efficiently produce large-length-diameter-ratio seamless laminated shafts, and has the advantages of high production efficiency, high size precision and simple equipment structure. However, in the deformation and composite process of cross-rolling, due to the action of the unilateral roller, the cross section of the laminated shaft undergoes continuous shape transformation from a circle to a triangle and then back to a circle, which reduces the bonding strength of the laminated shaft. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a rolling and expanding bidirectional lamination method for layered double-metal composite hollow shafts, which can significantly improve the bonding strength of the composite hollow shaft and ensure the forming quality of the composite hollow shaft.

[0004] The technical solution adopted by the present application to solve the above technical problem is as follows: A rolling and expanding bidirectional lamination method for layered double-metal composite hollow shafts, comprising the following specific steps: (1) Assembling an outer shaft and an inner shaft of metal material in interference to obtain an initial composite hollow shaft; (2) Heating the initial composite hollow shaft, a roller in a three-roll cross-rolling machine and an expanding rod, then feeding the initial composite hollow shaft into the three-roll cross-rolling machine, when the roller cross-rolls the initial composite hollow shaft, the expanding rod simultaneously extends into the inner hole of the initial composite hollow shaft, and the outer diameter of the expanding rod is greater than the inner hole diameter of the initial composite hollow shaft, so that the roller and the expanding rod simultaneously perform inner expansion and outer rolling bidirectional compression on the initial composite hollow shaft in the radial direction during rolling; (3) Axially pushing the initial composite hollow shaft forward, while keeping the axial relative position of the roller and the expanding rod unchanged, until the lamination rolling of the whole composite hollow shaft is completed, to obtain a layered double-metal composite hollow shaft.

[0005] Further, in step (1), the inner circumferential surface of the outer shaft and the outer circumferential surface of the inner shaft are polished and cleaned before the interference assembly of the outer shaft and the inner shaft.

[0006] Further, in step (1), the contact interfaces between the inner shaft and the outer shaft at the two end portions of the initial composite hollow shaft are welded respectively to prevent dislocation of the inner shaft and the outer shaft during rolling.

[0007] Further, in step (2), the outer diameter of the hole expanding rod is greater than the inner hole diameter of the initial composite hollow shaft and less than or equal to the outer diameter of the inner shaft.

[0008] Further, in step (3), if a stepped composite hollow shaft needs to be rolled, the roller can be moved radially during the rolling of the initial composite hollow shaft.

[0009] Compared with the prior art, the advantages of the present application are that, due to the outer diameter of the hole expanding rod being greater than the inner hole diameter of the initial composite hollow shaft, the roller and the hole expanding rod simultaneously perform inner expansion and outer rolling bidirectional compression on the composite hollow shaft in the radial direction during rolling, avoiding the repeated change of the cross section of the composite hollow shaft in the traditional three-roll cross rolling composite process, making the cross section deformation of the composite hollow shaft coordinated, and significantly improving the bonding strength of the composite hollow shaft. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a cross rolling schematic diagram of the composite hollow shaft of the present application; Figure 2 is a cross rolling process diagram of the composite hollow shaft of the present application; Figure 3 is a simulation comparison schematic diagram of the present application and the traditional method; Figure 4 is an equivalent strain analysis comparison diagram of the present application and the traditional method. DETAILED DESCRIPTION

[0011] The present application will be further described in detail below with reference to the embodiments of the drawings.

[0012] As shown in the figure, a cross rolling and expanding bidirectional lamination method of a laminated bimetal composite hollow shaft, comprising the following specific steps: (1) The inner circumferential surface of the outer shaft 1 and the outer circumferential surface of the inner shaft 2 are polished and cleaned, and then the outer shaft 1 and the inner shaft 2 are interference assembled by a press to obtain an initial composite hollow shaft 10; (2) The contact interfaces between the inner shaft 2 and the outer shaft 1 at the two end portions of the initial composite hollow shaft 10 are welded respectively to prevent dislocation of the inner shaft 2 and the outer shaft 1 during rolling; (3) Heat the initial composite hollow shaft 10, the rolls 3 and the expansion rod 4 in the three-roll skew mill to the required temperature for skew rolling, and then feed the initial composite hollow shaft 10 into the three-roll skew mill, such as... Figure 2 As shown in (a), when the roll 3 performs skew rolling on the initial composite hollow shaft 10, the expanding rod 4 simultaneously extends into the inner hole 11 of the initial composite hollow shaft 10. The outer diameter of the expanding rod 4 is greater than the diameter of the inner hole 11 of the initial composite hollow shaft 10 and less than or equal to the outer diameter of the inner shaft 2. This causes the roll 3 and the expanding rod 4 to simultaneously perform bidirectional compression of the initial composite hollow shaft 10 in the radial direction, such as... Figure 2 As shown in (b); (4) Push the initial composite hollow shaft 10 forward axially, while keeping the axial relative position of the roll 3 and the expanding rod 4 unchanged, such as Figure 2 As shown in (c), the lamination and rolling of the entire composite hollow shaft is completed to obtain a layered bimetallic composite hollow shaft.

[0013] Furthermore, if the layered bimetallic composite hollow shaft to be rolled is a stepped shaft, then during the rolling process in step (4), the roll 3 only needs to be moved radially according to the dimensional parameters of the stepped shaft, such as... Figure 2 As shown in (d) and (e).

[0014] Initial composite hollow shafts of the same material and specifications were subjected to rolling simulations using the bidirectional lamination method of this invention and the traditional three-roll skew rolling method. The results are compared below: Figure 3 (a) is a simulation diagram of the roll-expanded bidirectional lamination method of the present invention. Figure 3 (b) is a simulation diagram of the traditional three-roll skew rolling method. The equivalent strain cloud diagram reflects the deformation behavior inside the material. As can be seen from the figure, when the layered bimetallic hollow shaft is composited using the rolling-expansion bidirectional lamination method of the present invention, the color representing the magnitude of plastic strain at the cross-section is basically red; while when the layered bimetallic hollow shaft is composited using the traditional three-roll skew rolling method, the color representing the magnitude of plastic strain at the same cross-section changes from red to yellow. It can be seen that the layered bimetallic hollow shaft obtained by the method of the present invention has a more uniform distribution of plastic strain inside the material.

[0015] For further analysis Figure 3 The plastic strain distribution behavior of the two in the radial direction is respectively in Figure 3 (a) Position 1 and Figure 3 (b) Ten points were uniformly selected in the radial direction at position 2, and their plastic strain distribution was statistically analyzed, such as... Figure 4As shown in the figure, the equivalent plastic strain fluctuation range in the radial direction of the layered bimetallic hollow shaft obtained by the rolling-expansion bidirectional lamination method of the present invention is only 0.647; while the layered bimetallic hollow shaft obtained by the conventional three-roll skew rolling method has a plastic strain gradient due to the asymmetry of its deformation, that is, the deformation degree of the material on the outer surface is much higher than that on the inner surface, so its equivalent plastic strain fluctuation range reaches 1.560. This further illustrates that the plastic strain distribution inside the material of the layered bimetallic hollow shaft obtained by the method of the present invention is more uniform. It can be seen that the rolling-expansion bidirectional lamination method of the present invention can effectively improve the deformation uniformity of the layered bimetallic composite hollow shaft during the composite process and improve the bonding quality.

[0016] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.

Claims

1. A method for bidirectional lamination of layered bimetallic composite hollow shafts by rolling and expansion, characterized in that... The specific steps include the following: (1) The outer and inner shafts made of metal are interference-fitted to obtain the initial composite hollow shaft; (2) Heat the initial composite hollow shaft, the rolls and the expansion rod in the three-roll skew rolling mill respectively, and then feed the initial composite hollow shaft into the three-roll skew rolling mill. When the rolls perform skew rolling on the initial composite hollow shaft, the expansion rod extends into the inner hole of the initial composite hollow shaft at the same time, and the outer diameter of the expansion rod is larger than the inner diameter of the initial composite hollow shaft, so that the rolls and the expansion rod simultaneously perform bidirectional compression of the initial composite hollow shaft in the radial direction in the radial direction; (3) Push the initial composite hollow shaft forward axially while keeping the axial relative position of the roll and the expansion rod unchanged until the lamination rolling of the entire composite hollow shaft is completed, and a layered bimetallic composite hollow shaft is obtained.

2. The method for biaxial lamination of layered bimetallic composite hollow shafts by rolling and expanding as described in claim 1, characterized in that: In step (1), before the outer shaft and inner shaft are pressurized and cleaned, the inner circumferential surface of the outer shaft and the outer circumferential surface of the inner shaft are ground and cleaned.

3. The method for biaxial lamination of layered bimetallic composite hollow shafts by rolling and expanding as described in claim 1, characterized in that: In step (1), the contact interfaces between the inner and outer shafts at both ends of the initial composite hollow shaft are welded to prevent misalignment of the inner and outer shafts during the rolling process.

4. The method for biaxial lamination of layered bimetallic composite hollow shafts by rolling and expanding as described in claim 1, characterized in that: In step (2), the outer diameter of the expanding rod is greater than the inner diameter of the initial composite hollow shaft and less than or equal to the outer diameter of the inner shaft.

5. The method for biaxial lamination of layered bimetallic composite hollow shafts by rolling and expanding as described in claim 1, characterized in that: In step (3), if it is necessary to roll a stepped composite hollow shaft, the rollers can be moved radially during the rolling process of the initial composite hollow shaft.

Images