CN114523016A

CN114523016A - Rolling strengthening processing method for concave circular arc surface of turbine disc mortise

Info

Publication number: CN114523016A
Application number: CN202210152421.0A
Authority: CN
Inventors: 李勋; 赵文硕; 张鸿滨
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2022-02-18
Filing date: 2022-02-18
Publication date: 2022-05-24
Anticipated expiration: 2042-02-18
Also published as: CN114523016B

Abstract

The invention relates to a rolling strengthening processing method for a concave arc surface of a turbine disc mortise, which comprises the following steps: s1: designing a rolling head matched with the shape of the concave arc of the turbine disc mortise, wherein the diameter of the rolling head is smaller than the minimum width of a rolling contact point of the rolling head and the turbine disc mortise; the included angle of the tangent lines at the two ends of the convex circular arc of the rolling head is smaller than the included angle of the tangent lines at the two ends of the concave circular arc of the mortise, so that the length of the contact line of the rolling head and the concave circular arc of the mortise is reduced, the contact stress of rolling processing is improved, and plastic deformation strengthening processing is realized. S2: the turbine disc and the rolling head are respectively arranged on a workbench of a numerical control machine tool and a tool shank at a main shaft end, so that the rolling head can freely rotate relative to the tool shank. S3: and adjusting the pre-pressing amount of the rolling head and the concave arc of the mortise by contacting the convex arc surface of the rolling head with the concave arc of the mortise in the profile of the single side of the mortise of the turbine disc. S4: and (3) compiling a rolling numerical control program, controlling the motion track of the rolling head, ensuring the stability of the pre-pressing amount and carrying out strengthening processing on the surface of the concave arc of the mortise.

Description

Rolling strengthening processing method for concave circular arc surface of turbine disc mortise

Technical Field

The invention belongs to the technical field of fatigue-resistant manufacturing of structural features of aero-engine parts, and particularly relates to a rolling strengthening processing method for a concave arc surface of a mortise of a turbine disc.

Background

An aircraft engine turbine disk is an important hot-end rotor component of an engine. The turbine disc is subjected to the combined action of high temperature and cyclic stress in the working process, and fatigue fracture damage is easily caused at the stress concentration part of the mortise structure, so that aviation accidents are caused.

Fatigue failure of an aircraft engine turbine disk often occurs at the mortise concave arc, which is also the stress concentration zone of the turbine disk mortise in operation. Therefore, the surface of the concave arc of the mortise of the turbine disc needs to be subjected to strengthening processing, so that the surface performance of the turbine disc is improved, and the occurrence of aviation accidents due to fracture and damage caused by fatigue is avoided. Currently, the common strengthening methods for machining the surface include mechanical shot peening, laser shock peening, and surface extrusion peening. However, if the machining process is adopted to perform strengthening machining on the concave arc surface of the turbine disc mortise, the following disadvantages are present:

for the machining methods of mechanical shot peening and laser shock peening, the width of the turbine disk mortise is small, the outline shape is extremely complex, the position and the spray angle of a nozzle for mechanical shot peening and the light path for laser shock peening are difficult to be optimized and set, and the effect of surface peening cannot meet the design requirement, so that the application of mechanical shot peening and laser shock peening in the aspect of surface peening of the turbine disk mortise is limited. In addition, the mechanical shot peening and the laser shock peening can greatly improve the surface roughness of the strengthened surface and influence the overall profile precision of the mortise, so that the mechanical shot peening and the laser shock peening are not popularized and applied on the surface of the mortise of the turbine disc.

In general, surface cold extrusion strengthening is widely used for strengthening of hole wall surfaces or other closed and regular-shaped surfaces. The turbine disc mortise has complex profile and excellent material performance, and has high requirements on the shape precision, the material strength and the wear resistance of an extrusion tool, so that different surface extrusion amounts are difficult to realize by accurately controlling the size of the extrusion tool, and the application of surface cold extrusion strengthening in the aspect of surface strengthening of the turbine disc mortise profile is greatly limited.

Therefore, it is desirable to provide a method for strengthening the concave arc surface of the turbine disk.

Disclosure of Invention

Technical problem to be solved

Therefore, in order to solve the problems of high difficulty, poor strengthening effect and low automation degree in strengthening processing of the concave arc surface of the turbine disc mortise in the prior art, the invention provides a rolling strengthening processing method of the concave arc surface of the turbine disc mortise.

(II) technical scheme

In order to achieve the purpose, the invention adopts the main technical scheme that:

a rolling strengthening processing method for a concave arc surface of a turbine disc mortise comprises the following steps:

s1: designing a rolling head with a convex circular arc, wherein the convex circular arc of the rolling head is matched with the shape of a concave circular arc, a mortise and a concave circular arc on a mortise of a turbine disc and a mortise; the diameter of the rolling head is smaller than the minimum width of the rolling contact point of the rolling head and the turbine disc mortise of the turbine disc mortise; the included angle formed by the tangents of the two end points of the convex circular arc is smaller than the included angle formed by the tangents of the two end points of the mortise concave circular arc;

s2: the method comprises the following steps that a turbine disc and a rolling head are respectively installed on a workbench of a numerical control machine tool and a tool handle at a main shaft end, the rolling head is installed in the tool handle through an assembling component, and the rolling head can rotate relative to the assembling component and the tool handle;

s3: adjusting the convex arc of the rolling head to be in contact with a mortise concave arc in the single-side profile of the mortise of the turbine disc through a numerical control machine tool, and adjusting the pre-pressing amount of the rolling head and the mortise concave arc surface;

s4: and (4) compiling a rolling numerical control program, controlling the motion track of the rolling head through the movement of the cutter handle, enabling the pre-pressing amount in the rolling strengthening process of the rolling head to be consistent with the pre-pressing amount in the step S3, and carrying out surface strengthening processing on the mortise concave arc, the tongue groove concave arc and the tongue groove concave arc.

In the rolling strengthening processing method of the concave arc surface of the turbine disk mortise, in step S1, the diameter of the rolling head is preferably 0.5-1.5mm smaller than the minimum width of the rolling contact point of the rolling head and the turbine disk mortise.

In the rolling strengthening processing method for the turbine disc mortise concave circular arc surface, in step S1, preferably, the included angle α formed by the tangents of the two end points of the convex circular arc is 5 to 15 degrees smaller than the included angle β formed by the tangents of the two end points of the mortise concave circular arc.

In the rolling strengthening processing method for the concave arc surface of the turbine disc mortise, in step S2, preferably, after the turbine disc and the rolling head are respectively mounted on the workbench of the numerical control machine and the tool holder at the spindle end, the central axis of the rolling head is parallel to the symmetry plane of the turbine disc mortise.

In the rolling strengthening processing method for the concave arc surface of the turbine disc mortise, preferably, in step S2, the assembling component includes a mounting outer sleeve and a bearing; the mounting outer sleeve is fixed inside the cutter handle, and the bearing is arranged between the mounting outer sleeve and the rolling head; the rotation axis of the rolling head is parallel to the symmetry plane of the turbine disc mortise.

(III) advantageous effects

The invention has the beneficial effects that:

according to the invention, the rolling head serving as a rolling strengthening tool is arranged on the tool handle of the numerical control machine, and the turbine disc is arranged on the working platform of the numerical control machine, so that the diameter of the rolling head is smaller than the minimum width of the rolling contact point of the rolling head and the turbine disc mortise, and the rolling amount is accurately and conveniently controlled through the moving shaft of the numerical control machine. The invention can also utilize the automatic tool changing system of the numerical control machine tool to realize the automatic replacement of rolling heads with different sizes, and is convenient for realizing the automation of the rolling processing of the concave circular arc of the mortise.

In addition, the included angle formed by the tangents of the two end points of the convex arc is smaller than the included angle formed by the tangents of the two end points of the mortise concave arc, the convex arc of the rolling head is ensured to be only contacted with one mortise concave arc in the single-side profile of the mortise of the turbine disc in the processing process, the contact of the rolling head and the positions except the mortise concave arc in the rolling process is reduced, the length of the contact line of the rolling head and the mortise concave arc can be reduced, the contact stress of the rolling process is improved, and the plastic deformation strengthening processing of the mortise concave arc of the turbine disc is realized. The rolling strengthening is a non-cutting processing technology, waste chips and waste liquid cannot be generated in the processing process, the environment is friendly, and the roughness of the circular arc surface of the mortise can be reduced.

Drawings

FIG. 1 is a schematic flow chart of a rolling and strengthening processing method according to the present invention;

FIG. 2 is a profile view of a turbine disk dovetail tooth of the present invention;

FIG. 3 is a view showing the contact position of the rolling head with the concave arc of the mortise in the present invention;

FIG. 4 is a schematic structural view of a concave arc of the mortise in accordance with the present invention;

FIG. 5 is a schematic view of the structure of a rolling head according to the present invention;

fig. 6 is a schematic diagram of the rolling motion track of the rolling head in the invention.

[ description of reference ]

1: a turbine disk; 2: a turbine disc mortise; 3: the mortise concave arc; 4: installing an outer sleeve; 5: a bearing; 6: rolling a head; 7: a spring clamp; 8: the motion track of the rolling head;

31: a third connection surface; 32: a fourth connection face; 61: a convex arc; 62: a first connection face; 63: a second connection face.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

Example 1

In general, a turbine disk requires a plurality of steps such as machining and surface strengthening. Wherein, the mechanical processing refers to cutting the turbine disc to obtain the basic shape of the mortise on the turbine disc. After machining, it is often necessary to perform surface strengthening machining on the turbine disk tongue-and-groove to improve the fatigue resistance of the turbine disk tongue-and-groove. The machining is generally performed on a numerical control machine tool, a turbine disc is fixed on a working platform of the numerical control machine tool, and a milling cutter and the like mounted on a tool holder are driven by a main shaft to perform cutting machining on the turbine disc.

As shown in fig. 1 to 6, the present embodiment provides a rolling strengthening processing method for a concave arc surface of a mortise of a turbine disk after completion of machining.

Before describing the method of the present embodiment, the basic structure and end faces of the turbine disk will be briefly described: as shown in fig. 2 and 4, the turbine disk 1 includes a plurality of identical turbine disk mortises 3, and each turbine disk mortise 3 includes a plurality of tenons therein. The turbine disc is very easy to be damaged by fatigue fracture at the stress concentration part of the mortise structure, namely the tenon tooth part, so that aviation accidents are caused. Therefore, in the present embodiment, when performing surface strengthening processing on the turbine disk mortise, only the mortise concave arc 3 indicated in fig. 4 is considered to be subjected to surface rolling strengthening, and the third connection surface 31 and the fourth connection surface 32 on both sides of the mortise concave arc 3 are not subjected to rolling processing.

The rolling strengthening processing method of the concave arc surface of the mortise of the turbine disc comprises the following steps:

s1: the rolling head 6 with the convex circular arc 61 is designed, so that the convex circular arc 61 of the rolling head 6 is matched with the shape of the mortise concave circular arc 3 on the turbine disc mortise 2. Specifically, in the present embodiment, the rolling head 6 needs to satisfy the following two conditions: first, the diameter of the rolling head 6 is smaller than the minimum width at the rolling contact point of the rolling head 6 with the turbine disc mortise 2. The rolling contact point refers to the position to be processed in the mortise of the turbine disc, namely the mortise concave arc 3. Secondly, the included angle formed by the tangents of the two end points of the convex arc 61 is smaller than the included angle formed by the tangents of the two end points of the mortise concave arc 3. As shown in the figure, the rolling head 6 has a table shape as a whole, and includes a convex arc surface 61, a first connecting surface 62 connected to both sides of the convex arc surface 61, and a second connecting surface 63. The first connecting surface 62 and the second connecting surface 63 may be inclined planes or curved planes, preferably inclined planes in fig. 5, and an included angle formed by the first connecting surface 62 and the second connecting surface 63 is an included angle formed by tangents of two end points of the convex circular arc 61. Similarly, the third connecting surface 31 and the fourth connecting surface 32 may be inclined planes, or curved planes, preferably planes, and when the third connecting surface 31 and the fourth connecting surface 32 are planes, an included angle formed by the third connecting surface 31 and the fourth connecting surface 32 is an included angle formed by tangents of two end points of the mortise concave arc 3.

S2: the turbine disc and the rolling head 6 are respectively installed on a workbench of a numerical control machine tool and a tool handle of a spindle end, the rolling head 6 is installed in the tool handle through an assembling component, and the rolling head can freely rotate relative to the assembling component and the tool handle.

S3: and adjusting the contact of the convex arc 61 of the rolling head 6 with one mortise concave arc in the contour of the single side of the mortise of the turbine disc by using a numerical control machine tool, and adjusting the pre-pressing amount of the rolling head 6 and the surface of the mortise concave arc 3.

S4: and (4) programming a rolling numerical control program, controlling the motion track of the rolling head 6 through the movement of the cutter handle, keeping the pre-pressing amount of the rolling head 6 in the rolling strengthening process consistent with the pre-pressing amount in the step S3, and carrying out surface strengthening processing on the tongue-and-groove concave arc 3.

In step S1, the diameter of the rolling head 6 is smaller than the minimum width of the rolling contact point between the rolling head 6 and the turbine disc tongue-and-groove 2, so that it can be ensured that the rolling amount can be accurately and conveniently controlled by the moving shaft of the numerical control machine. Preferably, the diameter of the rolling head 6 is 0.5-1.5mm smaller than the minimum width at the rolling contact point of the turbine disc dovetail 2.

And the included angle formed by the tangents of the two end points of the convex circular arc is smaller than the included angle formed by the tangents of the two end points of the concave circular arc of the mortise, namely, the convex circular arc of the rolling head is only contacted with one side of the concave circular arc surface of the mortise of the turbine disc in the processing process in the rolling strengthening process, so that the contact of the rolling head 6 with the position except the concave circular arc 3 of the mortise in the rolling strengthening processing process can be reduced, the length of the contact line of the rolling head 6 and the concave circular arc 3 of the mortise can be reduced, the contact stress of the rolling processing is improved, the plastic deformation strengthening processing of the concave circular arc position of the mortise of the turbine disc is realized, and the phenomenon that the rolling strength and the effect cannot be obtained due to the fact that the first connecting surface 62 and the second connecting surface 63 in the rolling head 6 are too much contacted with the third connecting surface 31 and the fourth connecting surface 32 in the mortise of the turbine disc is dispersed. Preferably, in order to have a suitable contact area between the rolling head 6 and the turbine disc mortise, the included angle formed by the tangents of the two end points of the convex arc 61 is 5-15 ° smaller than the included angle formed by the tangents of the two end points of the mortise concave arc 3. If the included angle is smaller than the range, the contact area between the rolling head and the turbine disc mortise is too large, and the rolling processing strength cannot be ensured; if the contained angle is greater than this scope, then the area of contact undersize of rolling head and turbine disc tongue-and-groove, and rolling head structure itself is less, and area of contact is too big can make rolling head atress too big in the course of working, causes the damage easily.

In step S3, the rolling head itself has a small structure, so the convex arc 61 of the rolling head 6 only contacts with one mortise concave arc in the single-side profile of the turbine disc mortise each time, that is, the rolling head 6 only machines one mortise concave arc in the single-side mortise each time, so as to ensure the machining strength and the machining effect.

The turbine disk tongue and groove is not strictly a horizontal straight line structure and has a certain inclination, so that the path of the rolling head in the machining process can be oblique. In order to ensure that the pre-pressing amount of the rolling head on the mortise of the turbine disc is stable in the whole rolling strengthening processing process, in the step S4, the pre-pressing amount in the whole rolling processing process is ensured to be consistent with the pre-pressing amount preset in the step S3 through a rolling numerical control program, the stable pre-pressing amount in the whole rolling processing process is ensured, and then the stable rolling effect is ensured.

Preferably, in step S2, after the turbine disc 1 and the rolling head 6 are respectively mounted on the workbench of the numerical control machine tool and the tool holder at the spindle end, the central axis of the rolling head 6 is kept parallel to the symmetry plane of the turbine disc mortise 2, so that the rolling head 6 applies a relatively uniform rolling force to the turbine disc mortise.

In the embodiment, the rolling head 6 serving as a rolling strengthening tool is arranged on a handle of the numerical control machine tool, and the turbine disc 1 is arranged on a working platform of the numerical control machine tool. After the turbine disc is machined on the numerical control machine tool, rolling reinforcement can be carried out without detaching the turbine disc from a working platform of the numerical control machine tool. In the prior art, the machining of the turbine disc mortise is performed on a numerical control machine tool, and after the machining is completed, the surface strengthening machining needs to be performed after the turbine disc is detached. However, in this embodiment, the turbine disk does not need to be removed after the machining is completed, the tool for machining is directly replaced by the rolling head in this embodiment, the rolling reinforcement machining can be realized by controlling the movement of the rolling head through the main shaft of the numerical control machine, the turbine disk is prevented from being remounted, the machining can be performed under the original control track, the machining precision is higher, and the operation is also more convenient. In addition, the automatic tool changing system of the numerical control machine tool can be used for automatically replacing rolling heads with different sizes, and automation of rolling processing of the concave circular arc of the mortise is facilitated.

Preferably, in step S2, the assembly includes the mounting sleeve 4 and the bearing 5. The mounting outer sleeve 4 is fixedly mounted inside the cutter handle, and the bearing 5 is arranged between the rolling head 6 and the mounting outer sleeve 4, so that the rolling head 6 can freely rotate relative to the mounting outer sleeve 4. In addition, the roller head 6 is connected to the mounting sleeve 4 via a spring clip 7. Through the installation structure, in the rolling process of the step S4, the tool shank moves linearly under the control of the numerical control machine, so that the rolling head 6 rotates relative to the installation sleeve 4, and the power of the rolling head 6 moving along the mortise comes from the friction force between the rolling head 6 and the turbine disc mortise 2.

This embodiment does not drive the rolling head through the rotation of main shaft and carries out rotary motion, but drives installation overcoat horizontal migration through the main shaft, and then drives the rolling head and realize rotatoryly, carries out the rolling and reinforces processing, and concrete reason is because:

firstly, the size of the rolling head 6 is very small, and the general diameter is about several millimeters, however, the size of the main shaft and the tool holder in the numerical control machine tool is large, so that the fine small-sized movement is not easy to realize, and therefore, the rolling processing of the small turbine disc mortise cannot be realized. Secondly, the main shaft of digit control machine tool and the rotational speed of handle of a knife itself are very fast, if directly drive the rolling head rotatory and then carry out the roll extrusion to turbine disc tongue-and-groove, then rolling speed can be too fast, leads to the not good effect of roll extrusion reinforceing.

Referring to the motion track of the rolling head in fig. 6, in this embodiment, the main shaft, that is, the mounting sleeve 4, moves linearly under the action of the numerical control machine, the motion track is a straight line, and the rolling head 6 performs rolling along the route (r) with an arrow (a), (b) and (c).

This embodiment makes the concave arc surface of tongue-and-groove produce the sclerosis through the physical form that changes the turbine disk through pressurizing the concave arc surface of tongue-and-groove to the turbine disk with performance, quality and the life who improves the turbine disk, reduces the roughness on the concave arc surface of tongue-and-groove simultaneously. In addition, the rolling reinforcement is a non-cutting processing technology, and no scraps or waste liquid is generated in the processing process, so that the method is environment-friendly.

The above embodiments are merely illustrative, and not restrictive, of the scope of the invention, and those skilled in the art will be able to make various changes and modifications within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. A rolling strengthening processing method for a concave arc surface of a turbine disc mortise is characterized by comprising the following steps:

s1: designing a rolling head (6) with a convex circular arc (61), wherein the convex circular arc (61) of the rolling head (6) is matched with the shape of a mortise concave circular arc (3) on a turbine disc mortise (2); the diameter of the rolling head (6) is smaller than the minimum width of the rolling contact point of the rolling head (6) and the turbine disc mortise (2); the included angle formed by the tangents of the two end points of the convex circular arc (61) is smaller than the included angle formed by the tangents of the two end points of the mortise concave circular arc (3);

s2: the method comprises the following steps that a turbine disc (1) and a rolling head (6) are respectively installed on a workbench of a numerical control machine tool and a tool shank at a main shaft end, the rolling head (6) is installed in the tool shank through an assembling component, and the rolling head (6) can rotate relative to the assembling component and the tool shank;

s3: adjusting the contact of a convex circular arc (61) of the rolling head (6) and a mortise concave circular arc in the single-side profile of the mortise of the turbine disc through a numerical control machine tool, and adjusting the pre-pressing amount of the rolling head (6) and the surface of the mortise concave circular arc (3);

s4: and (5) programming a rolling numerical control program, controlling the motion track of the rolling head (6) through the movement of the cutter handle, enabling the pre-pressing amount in the rolling strengthening process of the rolling head (6) to be consistent with the pre-pressing amount in the step S3, and carrying out surface strengthening processing on the tongue-and-groove concave arc (3).

2. The method for roll strengthening the concave arc surface of the turbine disk mortise according to claim 1, wherein in step S1, the diameter of the rolling head (6) is 0.5-1.5mm smaller than the minimum width at the rolling contact point of the rolling head (6) and the turbine disk mortise (2).

3. The roll-strengthening processing method for the concave circular arc surface of the turbine disc mortise according to claim 1, wherein in step S1, the included angle formed by the tangents of the two end points of the convex circular arc (61) is 5-15 ° smaller than the included angle formed by the tangents of the two end points of the concave circular arc (3) of the mortise.

4. The method for rolling and strengthening the concave arc surface of the turbine disc mortise according to claim 1, wherein in step S2, after the turbine disc (1) and the rolling head (6) are respectively installed on a workbench of a numerical control machine and a tool shank of a spindle end, the central axis of the rolling head (6) is parallel to the symmetry plane of the turbine disc mortise (2).

5. The roll strengthening processing method for the concave arc surface of the turbine disc mortise according to claim 1, wherein in step S2, the assembly component comprises a mounting outer sleeve (4) and a bearing (5); the mounting outer sleeve (4) is fixed in the tool handle, and the bearing (5) is arranged between the mounting outer sleeve (4) and the rolling head (6); the rotation axis of the rolling head (6) is parallel to the symmetry plane of the turbine disc mortise (2).