Three roll skew rolling method for hollow shaft-type member having uniform thickness based on mandrel control

Abstract

Disclosed is a three roll skew rolling method, which can increase the number of times of finishing and the finishing time of the surface of the forming area of the rolled part formed by the rolling rollers in the rolling process, effectively reduce the defects of spiral marks on the surface of the rolled part, ensure the mechanical properties of the hollow shaft-based part, reduce the finishing margin of the subsequent machining, and reduce the waste of materials.SOLUTION: The rolling roller of the three roll inclined rolling mill is installed in a drum shape, and the shape of the rolling roller is optimized so that the rolling roller and a rolling member are brought into line contact with each other at an arbitrary time in the rectangular coordinate system of the rolling roller in a rolling process. In the rolling process, the pipe blank rolling member is first rolled in the diameter-reducing section, then rolled in the straight shaft section, and finally rolled in the diameter-increasing section to obtain a finished rolled member, wherein the shape of the rolling roller is optimized, so that the rolling roller and the rolled member are in line contact with each other at any time in the orthogonal coordinate system of the rolling roller during the rolling process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of tilt rolling of hollow shafts, and more particularly to a three-roll tilt rolling method for forming hollow shaft members of uniform thickness based on mandrel control. [Background technology]

[0002] Hollow axles not only meet the strength requirements of axles, but also significantly reduce the unsprung weight of trains, improving the stability and safety of power unit operation. Therefore, hollow axles are commonly used for train axles. Currently, the manufacturing and processing of hollow axles involves rolling a solid shaft blank and then drilling an inner hole. This method is simple, but it wastes a lot of material and requires a lot of subsequent cold working. Another method involves directly rolling the hollow blank into a hollow shaft by tilt rolling. This method has more significant material and energy savings than the above method, but the tilt rolling process inevitably produces spiral marks on the surface of the hollow shaft. These spiral marks reduce the mechanical properties of the hollow shaft and increase the finishing allowance for subsequent machining, resulting in material waste. Summary of the Invention [Problem to be solved by the invention]

[0003] The technical problem to be solved by the present invention is to provide a three-roll tilt rolling method for forming hollow shaft members of equal thickness based on mandrel control, which can effectively control the defect of spiral marks on the surface of the rolled member. [Means for solving the problem]

[0004] The technical solution used in the present invention to solve the above technical problems is as follows: A three-roll tilt rolling method for forming a hollow shaft member with a uniform wall thickness based on mandrel control, specifically: Step (1) of installing the rolling rollers of the three-roll tilt rolling mill to have a drum shape, i.e., to include a front cone portion, a cylindrical portion, and a rear cone portion installed in sequence; The relational expression for the work generatrix of the rolling roller is

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[0005] Furthermore, in the step (3), the magnitude of the radial movement speed of the rolling roller is V r , the magnitude of the axial movement speed of the mandrel is V x and V r =V x tan α1, thereby maintaining the gap between the cone surface of the front cone portion of the rolling roller and the cone surface of the mandrel unchanged during the diameter-reducing rolling process.

[0006] Furthermore, in steps (4) and (5), the axial moving speed of the tube material rolling member is equal to the axial moving speed of the tube material rolling member in step (3), and in step (5), the magnitude of the radial moving speed of the rolling roller is equal to the magnitude of the radial moving speed of the rolling roller in step (3), and V r The magnitude of the axial movement speed of the mandrel in step (5) is equal to the magnitude of the axial movement speed of the mandrel in step (3), and V x and V r =V x tan α1, thereby maintaining the gap between the cone surface of the front cone portion of the rolling roller and the cone surface of the mandrel unchanged during the diameter expansion rolling process.

[0007] Furthermore, the angle of the cone surface of the mandrel head is equal to or smaller than the forming angle α1 of the front cone of the rolling roller, and the maximum diameter of the mandrel head is smaller than the initial inner diameter of the tube material rolling member. [Effects of the Invention]

[0008] Compared with the prior art, the advantage of this method is that the shape of the rolling roller is optimized to ensure that the rolling roller and the rolled member are in line contact with each other at any time in the Cartesian coordinate system of the rolling roller during the rolling process, thereby increasing the number of times and time for finishing the surface of the forming area of ​​the rolled member by the rolling roller during the rolling process, effectively reducing the defects of spiral marks on the surface of the rolled member, ensuring the mechanical properties of the hollow shaft member, reducing the finishing allowance in subsequent machining, and reducing material waste.In addition, by controlling the radial moving speed of the rolling roller and the axial moving speed of the mandrel during the reduction and expansion rolling processes, the gap between the cone surface of the front cone part of the rolling roller and the cone surface of the mandrel can be kept constant, making the wall thickness of the rolled hollow shaft member uniform and consistent, contributing to the accurate forming of the inner and outer surfaces of the hollow shaft member with uniform wall thickness. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the cooperation of a rolling roller, a rolling member, a four-jaw chuck, and a mandrel in a rolling process according to the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the structure of a rolling roller according to the present invention. [Figure 3] FIG. 3 is a structural schematic diagram of the mandrel according to the present invention. [Figure 4] FIG. 4 is a comparative diagram showing projections of the rolling roller and the rolling member in the rolling process according to the present invention. [Figure 5] FIG. 5 is a left side view of section II in FIG. [Figure 6] FIG. 6 is a schematic view showing the rolling state of the reduced diameter portion of the rolled tube material according to the present invention. [Figure 7] FIG. 7 is a schematic view showing the rolling state of the straight shaft portion of the rolled tube material according to the present invention. [Figure 8] FIG. 8 is a schematic view showing the rolling state of the expanded diameter portion of the rolled tube material according to the present invention. [Figure 9]9A and 9B are right projection views of the rolling roller contacting the rolling member in different rolling stages according to the present invention. [Figure 10] FIG. 10 is a diagram showing the effect of a rolled member obtained by rolling with a normal disk-shaped rolling roller. [Figure 11] FIG. 11 is a diagram showing the effect of a rolled member obtained by rolling with the optimized rolling roller according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will now be described in more detail by way of examples with reference to the drawings.

[0011] As shown in the figure, the three-roll tilt rolling method for forming a hollow shaft member of uniform thickness based on mandrel control, specifically, Step (1) of installing the rolling roller 1 of the three-roll tilt rolling mill so that it is drum-shaped, i.e., includes a front cone portion 11, a cylindrical portion 12, and a rear cone portion 13 which are sequentially installed; The relational expression of the work generatrix of the rolling roller 1 is

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[0012] The specific process of deriving the relational expression for the work generatrix of the rolling roller in the present invention is as follows.

[0013] Because the roller surface areas of the rolling rollers contacting the rolling members at different rolling stages of the hollow axle for three-roll inclined rolling are different, the right projection views of the rolling rollers 1 contacting the rolling members at different rolling stages are shown in Figure 9. In order to rationally design the working busbars of the rolling rollers at each stage, the design process of the working busbars of the rolling rollers at different rolling stages is as follows:

[0014] (1) The radius of any point on the work generatrix of the rolling roller when the rolled member is being rolled to expand its diameter. Sections II to L on the front cone part 11 of the rolling roller 1 along the axis of the rolling member 1x At the point where the rolling roller leaves, take a cross section x1-x1 that is perpendicular to the axis of the rolling member, and the axis O of the rolling roller on the cross section x1-x1 x1 The projection in the right view is shown in Fig. 9(a), and according to Fig. 9(a),

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[0015] As can be seen from equation (1), in order for the rolling roller 1 to maintain line contact with the rolling member in the Cartesian coordinate system of the rolling roller when the rolling roller performs diameter reduction rolling, the ideal radius R of the rolling roller at the cross section x1-x1 is x1 teeth, R x1 =O x1 O1-r1(2), That is,

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[0016] (2) The radius of any point on the work generatrix of the rolling roller when the rolling member is rolling the straight shaft part. Sections II to L on the cylindrical part 12 of the rolling roller 1 along the axis of the rolling member 2x At the point where they separate, take a cross section x2-x2 that is perpendicular to the axis of the rolling member, and find the axis O of the rolling roller on the cross section x2-x2. x2 The projection in the right view is shown in Fig. 9(b), and according to Fig. 9(b),

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[0017] As can be seen from equation (4), in order for the rolling roller 1 to maintain line contact with the rolling member in the Cartesian coordinate system of the rolling roller when the rolling roller performs straight-axis rolling, the ideal radius R of the rolling roller at the cross section x2-x2 is x2 teeth, R x2 =O x2 O1-r0(5), That is,

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[0018] (3) The radius of any point on the work generatrix of the rolling roller when the rolled member is undergoing diameter reduction rolling. Cross section II to L on the rear cone part 13 of the rolling roller 1 along the axis of the rolling member 3x At the point where the roller leaves, take a cross section x3-x3 that is perpendicular to the axis of the rolling member, and the axis O of the rolling roller on the cross section x3-x3 x3 The projection in the right view is shown in Fig. 9(c), and according to Fig. 9(c),

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[0019] As can be seen from equation (7), in order for the rolling roller 1 to maintain line contact with the rolling member in the Cartesian coordinate system of the rolling roller when the rolling roller performs diameter expansion rolling, the ideal radius R of the rolling roller at the cross section x3-x3 is x3 teeth, R x3 =O x3 O1-r3(8), That is,

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[0020] By simultaneously setting up the equations (3), (6), and (9), the relational equation of the work generatrix of the rolling roller for making the rolling roller 1 and the rolling member come into line contact at any time in the Cartesian coordinate system of the rolling roller throughout the rolling process is given as follows:

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[0021] Experimental verification was carried out on the rolling effect of rolling a hollow shaft using a rolling roller optimized by this method, and the specific results are as follows.

[0022] Tube blanks of the same specifications were subjected to tilt rolling using the optimized drum-shaped rolling rollers of the present invention and ordinary disc-shaped rolling rollers in a three-roll tilt rolling mill, and the same process parameters (i.e., the rotational speed of the rolling rollers, the axial movement speed of the tube blank, and the radial movement speed of the rolling rollers) were used in the rolling process. A comparison of the forming quality of the surface of the rolled member obtained by rolling is shown in Figures 10 and 11. As can be seen from the above, the surface of the rolled member obtained by rolling with the optimized drum-shaped rolling rollers is smoother than the surface of the rolled member obtained by rolling with ordinary disc-shaped rolling rollers, and the maximum height R of the surface profile of the rolled member obtained by rolling with the optimized drum-shaped rolling rollers of the present invention under the same process parameters is z = 1.25, but the maximum height R of the surface profile of the rolled part obtained by rolling with a normal disk-shaped rolling roller z= 2.97, and the maximum height R of the surface profile of the rolled member z is the evaluation index of the spiral marks on the surface of the rolled member, the deviation between the actual contour line of the rolled member and the theoretical contour line is the contour deviation of the rolled member, which is represented by d, and the maximum height R of the surface contour of the rolled member z R z =d max -d min where d max is the maximum contour deviation, and d min is the minimum profile deviation. As can be seen from this, by rolling a hollow shafting member with the optimized drum-shaped rolling roller according to the present invention, it is possible to effectively control the defect of spiral marks on the surface of the rolled member. In addition, this method can make the wall thickness of the hollow shafting member more uniform.

[0023] The scope of protection of the present invention includes, but is not limited to, the above embodiments, and the scope of protection is pursuant to the claims, and any replacements, modifications, and improvements that can be easily thought of by a person skilled in the art are all included in the scope of protection of the present invention.

Claims

1. A three-roll tilt rolling method for forming a hollow shaft member having a uniform wall thickness based on mandrel control, specifically, Step (1) of installing the rolling rollers of a three-roll tilt rolling mill in a drum shape, i.e., including a front cone portion, a cylindrical portion, and a rear cone portion, which are installed in sequence; The relational expression for the work generatrix of the rolling roller is [Equation 1] Set it to be During the rolling process, the rolling roller and the rolling member are in line contact at any time in the Cartesian coordinate system of the rolling roller, R is the radius of the rolling roller at the cross section I-I taken perpendicular to the axis of the rolling member on the rolling roller and through the intersection point between the axis of the rolling member and the axis of the rolling roller, and r ０ is the outer radius of the cross section of the rolling member corresponding to cross section I-I, x is the distance from cross section x-x on the rolling roller to cross section I-I, cross section x-x is a cross section perpendicular to the axis of the rolling member on the rolling roller and parallel to cross section I-I, β is the deflection angle of the axis of the rolling roller with respect to the axis of the rolling member, and L １ is the length of the front cone of the rolling roller, and L ２ is the length of the cylindrical part of the rolling roller, and L ３ is the length of the rear cone part of the rolling roller, and α １ is the forming angle of the front cone part of the rolling roller, and α ３ Step (2) where is the forming angle of the rear cone portion of the rolling roller and y is the radius of the rolling roller at the cross section x-x on the rolling roller; Step (3): The tube material rolling member is placed in a three-roll tilt rolling mill; during rolling, the rolling rollers are controlled to rotate around their axes and move radially toward the tube material rolling member to roll a reduced diameter portion of the tube material rolling member; the four-jaw chucks are controlled to move axially at a constant speed while sandwiching the tube material rolling member, inserting a tapered mandrel into the tube material rolling member and moving the mandrel axially, so that the mandrel moves in the opposite direction to the moving direction of the tube material rolling member, and maintaining the gap between the cone surface of the front cone of the rolling roller and the cone surface of the mandrel unchanged during the reduced diameter rolling process; After the rolling of the reduced diameter portion is completed, the rolling rollers are maintained not to move in the radial direction, the four-jaw chuck continues to move at the same speed along the axial direction while sandwiching the tube blank rolling member, and the mandrel is controlled to stop moving in the axial direction, thereby rolling the straight shaft portion of the tube blank rolling member; and and (5) after the rolling of the straight shaft portion is completed, the four-jaw chuck continues to move at the same speed along the axial direction while sandwiching the tube material rolling member, the rolling rollers move radially away from the tube material rolling member to roll the expanded diameter portion into the tube material rolling member, and the mandrel is controlled to move axially so that the moving direction of the mandrel is the same as the moving direction of the tube material rolling member, and the gap between the cone surface of the front cone portion of the rolling roller and the cone surface of the mandrel is maintained unchanged during the expanding diameter rolling process until the rolling of the expanded diameter portion is completed, thereby obtaining a finished rolled member.

2. In the step (3), the magnitude of the radial movement speed of the rolling roller is V ｒ , the magnitude of the axial movement speed of the mandrel is V ｘ and V ｒ =V ｘ Tanα １ 2. The three-roll tilt rolling method for forming hollow shaft members of uniform thickness based on mandrel control according to claim 1, wherein the gap between the cone surface of the front cone portion of the rolling roller and the cone surface of the mandrel is maintained unchanged during the diameter reduction rolling process.

3. In the steps (4) and (5), the axial moving speed of the tube material rolling member is equal to the axial moving speed of the tube material rolling member in step (3), and in the step (5), the magnitude of the radial moving speed of the rolling roller is equal to the magnitude of the radial moving speed of the rolling roller in step (3), and V ｒ The magnitude of the axial movement speed of the mandrel in step (5) is equal to the magnitude of the axial movement speed of the mandrel in step (3), and V ｘ and V ｒ =V ｘ Tanα １ 3. The three-roll tilt rolling method for forming hollow shaft members of uniform thickness based on mandrel control according to claim 2, wherein the gap between the cone surface of the front cone portion of the rolling roller and the cone surface of the mandrel is maintained unchanged during the diameter expansion rolling process.

4. The angle of the cone surface of the head of the mandrel is the forming angle α of the front cone of the rolling roller. １ 2. A three-roll tilt rolling method for forming hollow shaft members with uniform wall thicknesses based on mandrel control as claimed in claim 1, characterized in that the maximum diameter of the head portion of the mandrel is smaller than the initial inner diameter of the tube material rolling member.

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