Combined pulse local loading continuous necking forming method

Abstract

According to the combined pulse local loading continuous necking forming method, a thin-wall pipe is adopted as an initial blank, at least two sets of array type hammer heads are continuously arranged in the axial direction to conduct pulse radial loading motion, and the contour formed by the working faces of the hammer heads is matched with the structural change of a continuous deformation section. The blank enters a high-frequency pulse loading area in the axial direction, and the radial size of the front end wall portion is reduced under the high-frequency and local small-deformation pulse loading effect. And then the blank is continuously fed in the axial direction, the front end part of the non-deformation area continuously enters the loading area, and the deformation amount is continuously and uniformly accumulated. The method can be suitable for components with different complex characteristics such as variable diameters and variable curvatures, and compared with a traditional necking mode, the deformation mode can be changed, the instability wrinkling defect is restrained, and the necking forming limit is improved. The method has remarkable advantages especially for large-size components with complex structures such as large length-diameter ratio, large diameter-thickness ratio extreme size characteristic composite and long-distance continuous deformation sections.

Description

Technical Field

[0001] The present application relates to the technical field of material processing, and in particular to a combined pulse local loading continuous shrinking forming method. Background Art

[0002] Neck shrinking is an important method to reduce the diameter of the pipe end.

[0003] The main current methods include extrusion forming, rotary shrinking forming and radial forging. Among them, extrusion forming is formed by extruding the tube blank as a whole to shrink one end of the tube blank as a whole. The shell formed by this process has problems such as large axial stress, uneven overall deformation, and easy to cause instability and wrinkling of the processed part. It is especially difficult to form large-sized, large aspect ratio, large diameter-thickness ratio, variable diameter / variable wall thickness and other complex structures. The rotary shrinking forming method cannot form overall circumferential compressive stress on the blank, which makes the blank easy to extend axially and produce cracks / wrinkling defects. In addition, radial forging mainly adopts radial pulse local loading to change the shell diameter reduction and thickening deformation mode, reduce the axial compressive stress of the blank during deformation, inhibit wrinkling and instability defects, and promote uniform deformation. However, the existing radial forging method can only form small-sized and simple-shaped shell components. The shell components with large size, large aspect ratio, large diameter-thickness ratio, variable diameter / variable wall thickness and other complex structures still have the problem of low forming limit due to uneven deformation.

[0004] Therefore, a new method of combined pulse continuous radial local loading continuous shrinking forming is urgently needed. Summary of the invention

[0005] The purpose of the present application is to provide a combined pulse local loading continuous shrinking forming method to solve the problems existing in the prior art such as shell structure forming instability and wrinkling, and uncoordinated deformation of various parts during the forming process.

[0006] The embodiments of the present application can be implemented through the following technical solutions:

[0007] A combined pulse local loading continuous shrinking forming method is used to load and form a blank fed along an axial direction, including the following operations:

[0008] Continuously feed the blank in the axial direction, and

[0009] Using each hammer in at least two-stage hammer combinations arranged continuously in the axial direction to perform pulsed radial local loading on the blank being continuously fed;

[0010] When each hammer included in any one-stage hammer combination is at the position with the smallest radial distance from the blank, its working surface forms the outer contour size of the blank at the hammer combination of this stage along the circumferential direction, and

[0011] Each hammer in each stage of the hammer assembly performs pulsed radial local loading on the outer wall of the blank through radial reciprocating motion;

[0012] The axial length of the hammers in each level of hammer assembly is determined based on the radial dimension change rate of the working surface.

[0013] Furthermore, the axial cross-section of the outer contour dimensions of each stage of the hammer head combination shrinks continuously or stepwise along the axial feeding direction of the blank.

[0014] Furthermore, the blank has a shell shape or a non-shell solid shape.

[0015] Furthermore, when the blank has a solid form other than a shell, the method further comprises the following steps:

[0016] A mandrel is used to abut against the end face of the blank in its feeding direction and fix the position of the mandrel, or the mandrel is used to abut against the end face of the blank in its feeding direction and the mandrel is continuously fed in a direction opposite to the feeding direction of the blank, wherein the mandrel is parallel to the axis of the blank.

[0017] Furthermore, the numbers of hammers included in each level of hammer assembly are unequal or equal.

[0018] Furthermore, when the number of hammers included in each level of hammer head combination is equal, the circumferential distribution of the hammers included in any level of hammer head combination is the same as or staggered with the circumferential distribution of the hammers included in the adjacent hammer head combination.

[0019] Furthermore, the circumferential distribution of each hammer head included in each level of hammer head combination deflects toward the same rotation direction as the number of levels increases.

[0020] Furthermore, the upper limit of the number of graded groups and the axial length of the hammer heads in each stage of the hammer head combination increases with the increase of the radial dimension change rate of the working surface.

[0021] Furthermore, radial loading amounts and / or frequencies of the hammers in each stage of the hammer assembly are the same and / or different.

[0022] Furthermore, the method also includes the step of preheating the blank.

[0023] Furthermore, the forming method specifically comprises the following steps:

[0024] Step 1: Using a thin-walled tube designed according to a forging as an initial blank, design and manufacture an array hammer suitable for combined pulse radial local loading;

[0025] Step 2: Assemble an array of hammers on the radial loading forming equipment to form at least two levels of hammer combinations continuously arranged along the axial direction, preheat the working surface and core rod of each level of hammer combination before forming, or adopt cold forming (without preheating) or without setting the core rod according to actual process requirements;

[0026] Step 3: Preheat the tube to the deformation temperature. The non-uniform temperature field of the billet can be set according to the actual process requirements, or cold forming can be performed according to the material deformation characteristics of the billet;

[0027] Step 4: Fix the blank on the clamping chuck and adjust the blank until its axis coincides with the axis of the combined pulse local loading deformation zone;

[0028] Step 5: Start the radial loading forming equipment to perform high-frequency combined pulse local loading;

[0029] Step 6: The blank is continuously fed into the high-frequency pulse loading area along the axial direction, and the radial size of the front wall of the blank is reduced; then the blank is continuously fed along the axial direction, the deformed area continues to extend toward the front end, and the front end of the undeformed area continuously enters the loading area, achieving overall uniform deformation to obtain a forging;

[0030] Step 7: Reversely eject the formed forging from the feed end.

[0031] Furthermore, the component material of the blank includes steel, aluminum alloy, titanium alloy, magnesium alloy, and a composite material with any one of these metal materials as a matrix.

[0032] The combined pulse local loading continuous shrinking forming method provided by the embodiment of the present application has at least the following beneficial effects:

[0033] By using each hammer in at least two-stage hammer combinations continuously arranged along the axial direction to perform pulsed radial local loading on the blank in the continuous feeding, the loading area can cover the long-distance continuous deformation section of the component, and evenly disperse the overall large shrinkage deformation into pulsed small deformation at different axial positions. By axially step-by-step hierarchical design of the combined hammers, combined with the coordinated optimization of the axial / circumferential distribution (axial width / spacing, circumferential distribution / angle relationship, etc.) of the working surfaces of each hammer, and graded regulation of the radial load and loading frequency at different deformation positions, it is possible to accurately control the local stable forming and continuous extension of the deformation zone, and realize the long-distance continuous shrinkage forming of the component.

[0034] In addition, compared with the overall loading shrinkage forming method, the radial local loading of the present invention can change the deformation mode of shrinkage forming, so that the maximum principal stress direction of the blank deformation zone changes from axial to radial, forming an overall circumferential compressive stress, effectively suppressing the instability wrinkling defect. Combined pulse loading can also uniformly and discretely control the overall shrinkage deformation of the component structure, and continuously and uniformly accumulate local small deformation loading, significantly improving the shrinkage forming limit, especially for large-sized components with complex structures such as large aspect ratio, large diameter-thickness ratio, and long-distance continuous deformation sections. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of the combined pulse continuous radial local loading forming method provided according to an embodiment of the present application;

[0036] Figure 2 A schematic diagram of an axial continuous loading area composed of a multi-stage hammer head combination according to some embodiments;

[0037] Figure 3 A schematic diagram of a two-stage hammer assembly provided according to an embodiment of the present application;

[0038] Figure 4 This is a schematic diagram of the principle of this application;

[0039] Figure 5 A schematic diagram of independently setting the loading frequency and loading amount of the loading area where each level of hammer assembly is located according to an embodiment of the present application;

[0040] Figure 6 A schematic diagram of changes in blank feed speed and radial strain according to an embodiment of the present application;

[0041] Figure 7 , Figure 8 This is a schematic diagram of the overall structure of an axially graded radial pulse loading mold device of the present application;

[0042] Fig. 9 This is a schematic diagram of an exploded state of an axially stepped radial pulse loading mold device of the present application;

[0043] Fig.10 It is a structural schematic diagram of the hammer head assembly in this application;

[0044] Fig.11 It is a structural schematic diagram of the annular chuck in this application;

[0045] Fig.12 It is a schematic diagram of the structure of the hammer head in this application;

[0046] Fig.13 It is a structural schematic diagram of the chute in this application;

[0047] Fig.14 For along Figure 3 Schematic diagram of the cross-sectional structure along the CC direction.

[0048] Numbers in the figure

[0049] 1- annular chuck; 10- mounting cover; 11- feeding hole; 12- guide groove; 13- groove; 14- receiving blind hole;

[0050] 2-Roller drive;

[0051] 310-first-stage hammer assembly; 320-second-stage hammer assembly; 330-third-stage hammer assembly;

[0052] 3- hammer head; 301- working surface; 302- driving surface; 31- hammer head slider; 32- hammer head member; 33- torsion spring; 34- gasket;

[0053] 4-chute; 41-first structure; 42-second structure;

[0054] 5-Elastic reset element. DETAILED DESCRIPTION

[0055] Hereinafter, the present application will be further described based on preferred embodiments with reference to the accompanying drawings.

[0056] In addition, various components on the drawings are enlarged (thickened) or reduced (thinned) for ease of understanding, but this practice is not intended to limit the scope of protection of the present application.

[0057] Words importing the singular also include the plural and vice versa.

[0058] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the products of the embodiments of the present application are usually placed when in use, it is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, in the description of the present application, in order to distinguish different units, the words first, second, etc. are used in this specification, but these are not limited by the order of manufacture, nor can they be understood as indicating or implying relative importance, and their names may be different in the detailed description and claims of the present application.

[0059] The vocabulary in this specification is used to illustrate the embodiments of the present application, but is not intended to limit the present application. It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, an indirect connection through an intermediate medium, or a connection between the two elements. For those skilled in the art, the specific meanings of the above terms in this application can be specifically understood.

[0060] The present application provides a combined pulse continuous radial local loading continuous shrinking forming method, which is used for loading and forming a blank fed along the axial direction.

[0061] Figure 1 In some embodiments, a schematic diagram of the forming method is shown, Figure 1 As shown, the method includes the following operations:

[0062] Step 620, continuously feeding the blank in the axial direction;

[0063] Step 640: Use each hammer in at least two stages of hammer assemblies continuously arranged along the axial direction to perform pulsed radial local loading on the continuously fed blank.

[0064] Wherein, step 620 is used to continuously feed the blank in the axial direction so that it enters a continuous loading area composed of at least two stages of hammer heads for radial pulse loading.

[0065] In some optional embodiments, the blank may have a shell shape, for example, a tube blank with equal wall thickness or unequal wall thickness, and the shape of the cross section of the tube may be various, for example, its outer wall and / or inner wall may be of equal diameter (i.e., circular) or of unequal diameter. Obviously, regardless of the wall thickness or cross-sectional characteristics, the tube blanks of various shell shapes have an axis, so the ends of the tube blanks may be clamped by a fixture and allowed to enter the continuous loading area along the axial direction through a feeding mechanism.

[0066] In some optional embodiments, the blank can be made of steel, aluminum alloy, titanium alloy, magnesium alloy, or a composite material with any of the above metal materials as a matrix. According to the characteristics of the blank material, it can be preheated to the deformation temperature before entering the loaded area to facilitate the subsequent loading process.

[0067] Step 640 is used to perform continuous pulsed radial local loading on the blank during the axial feeding process.

[0068] Specifically, in the present application, the continuous loading area is composed of at least two stages of hammer heads that are continuously arranged in the axial direction.

[0069] Figure 2 , Figure 3 Schematic diagrams of axial continuous loading areas composed of a multi-stage hammer assembly in a specific embodiment are respectively shown, in which the first-stage hammer assembly 310, the second-stage hammer assembly 320 and the third-stage hammer assembly 330 are continuously arranged along the feeding direction of the blank, and accordingly, the fourth-stage, fifth-stage ... n-stage hammer assemblies can be further arranged thereafter, and each stage of the hammer assembly is composed of four hammers distributed along the circumferential direction, wherein one end of each hammer facing the blank is its working surface, and during the continuous axial feeding of the blank, each hammer moves radially to The hammer head combination of any one level is used to perform pulsed radial local loading on the outer surface of the blank by using its working surface. Obviously, when each hammer head included in any one-level hammer head combination is at the position with the smallest radial distance from the blank, its working surface forms the outer contour dimension of the blank at that level of hammer head combination along the circumferential direction. Generally, the outer contour dimensions of each level of hammer head combination are continuously distributed along the axial direction, and the outer contour dimensions of each level of hammer head combination form a closed curved surface along the circumferential direction, and finally form a complete outer contour dimension together, with only a tiny gap between the working surfaces of adjacent hammer heads.

[0070] The following is combined with Figure 4 The mechanism and advantages of using a multi-stage hammer combination to perform pulsed continuous radial local loading on the billet during feeding are explained.

[0071] In a specific embodiment, the multi-stage hammer combination is used to perform pulsed continuous radial local loading on a billet (tube blank) in the form of a tube. The axis of the outer contour dimension formed by the working surface of each stage of the hammer combination coincides with the axis of the tube blank. During the continuous feeding of the tube blank through the clamping end of the clamp along its axial feeding direction, its front end first enters the loading area formed by the first-stage hammer combination. Under the pulse loading action of each hammer of the hammer combination at this stage, a diameter reduction and thickening deformation occurs in which the radial dimension is reduced and the wall thickness is increased. Subsequently, the tube blank is continuously fed along the axial direction, the deformed area continues to extend toward the front end, and the front end of the undeformed area continuously enters the deformation zone, thereby achieving overall uniform forming of the shell.

[0072] According to the difference in deformation rules at different axial positions of the blank, the loading rate and radial deformation amount ( Figure 5 ), and dynamically adjust the billet feed rate ( Figure 6 ) to adapt to the shrinkage deformation process requirements of different structural characteristics.

[0073] Figure 6 The figure shows the schematic diagram of the gradual change of the feed speed and radial strain at different hammer combinations during the continuous feeding of the shell-shaped blank in the working surface area formed by the hammer combinations of various levels, as shown in FIG. Figure 6As shown in the figure, when a shell-shaped blank (such as a tube blank) is subjected to a loading and forming process, the axial cross-section of the outer contour dimensions of each level of hammer head combination shrinks continuously or stepwise along the axial feed direction of the blank. As a result, as the feed displacement of the tube blank increases, its radial strain gradually increases to show a trend of reducing diameter and increasing thickening, and its axial feed speed gradually decreases.

[0074] Obviously, the axial length, quantity, circumferential distribution of each level of hammer combination, as well as the loading frequency and loading amount of pulsed radial local loading on different parts of the blank using each level of hammer combination can be determined according to the material properties, initial shape, final desired forming shape, etc. of the blank.

[0075] For example, in some embodiments, the number of hammers included in each hammer assembly may be the same, and the hammers in each hammer assembly and the hammers in its adjacent hammer assembly are aligned with each other, that is, their circumferential distribution is the same; in other embodiments, Figure 2 As shown, the number of hammers in each hammer assembly is the same, but the hammers in each hammer assembly are staggered circumferentially. The advantage of using staggered circumferential distribution is that the gaps between the hammers can be prevented from extending axially so that the blank at that location is always unable to be subjected to the loading force. In addition, more preferably, the circumferential distribution of each hammer included in each hammer assembly can be deflected in the same rotation direction as the number of stages increases. For example, the circumferential distribution of the second-stage hammer assembly 320 is deflected clockwise by an angle θ relative to the first-stage hammer assembly 310. Similarly, the circumferential distribution of the third-stage hammer assembly 330 is also deflected clockwise by an angle θ relative to the second-stage hammer assembly 320, so that when the blank gradually passes through each hammer assembly, its circumferential direction is loaded more evenly.

[0076] Each level of hammer combination can also contain different numbers of hammers, for example, Figure 3 In the illustrated embodiment, the first-stage and second-stage hammer assemblies include three hammers and four hammers, respectively.

[0077] The axial length of the hammers in each level of hammer combination can be the same, or it can also be determined according to the radial load of the blank at different positions in the loading area, that is, the axial length of the hammers in each level of hammer combination can also be determined based on the radial size change rate of the working surface. For example, in the area where the first level of hammer combination is located, the radial load of the blank is small, and only a slight radial strain occurs, that is, the axial projection line of the working surface of each hammer in this level of hammer combination has a small average curvature, so the axial length of each hammer in the first level of hammer combination can be extended; with the continuous feeding of the blank, the radial load of the blank at the second and third level of hammer combination gradually increases, so the axial projection line of the working surface of each hammer in each level of hammer combination increases with the radial size change rate of the working surface, and the radial strain required to be generated per unit axial distance also increases continuously, and at this time, the blank needs to be subjected to more refined radial loading, so the axial length of the hammer in the second and third level of hammer combination is continuously reduced. By using this variable axial length of the hammer, a good balance can be achieved between loading efficiency and loading accuracy.

[0078] In addition, the radial load and / or frequency of the hammers in each level of hammer combination can be independently controlled to be the same and / or different to achieve specific loading targets for different loading areas. Combined with the dynamic regulation of the billet feed rate, it can adapt to the differences in deformation laws at different axial positions of the component. For example, Figure 5 As shown, the loading frequency f and the loading amount h of the loading area where each level of hammer head combination is located can be set independently.

[0079] In some preferred embodiments, changing the shape of the working surface can shrink the tubes and shells with different diameter changes, curvature changes, and symmetrical / asymmetrical cross-sectional shapes, and can also be applied to the continuous diameter reduction forming of shells or rods.

[0080] Compared with the integral loading and diameter reduction and thickening deformation method used in the prior art, the forming method provided by the present application can change the shell diameter reduction and thickening deformation mode, so that the direction of the maximum compressive stress in the deformation zone of the blank changes from axial to radial, effectively suppressing unstable wrinkling defects, and at the same time discretely controlling the overall loading and deformation forming process of the shell structure (that is, in the traditional integral loading process, the deformation of each part of the blank is not coordinated due to the large structural differences, and the traditional overall loading deformation can be uniformly discreted by uniformly accumulating local small deformation amounts), promoting uniform deformation, and significantly improving the formability of the shell, especially for shells with large size, large aspect ratio, large diameter-thickness ratio, variable diameter / variable wall thickness and other complex structures.

[0081] In addition, as described above, the forming method provided in the present application can also be used to load and form a loaded part (such as a columnar blank) that has a solid shape other than a shell.

[0082] In some preferred embodiments, a core rod may be provided to constrain radial flow of metal, thereby improving the inner hole size accuracy and forming quality. The forming method may form components with a diameter range of 20 to 500 mm and a length of ≥ 2 m.

[0083] In some preferred embodiments, when the loaded part is a solid blank such as the above-mentioned columnar blank, the forming method further comprises the following steps:

[0084] A mandrel is used to abut against the end face of the loaded part in its feeding direction and the position of the mandrel is fixed, or the mandrel is used to abut against the end face of the loaded part in its feeding direction and the mandrel is continuously fed in a direction opposite to the feeding direction of the loaded part, wherein the mandrel is parallel to the axis of the loaded part.

[0085] By abutting the core rod in the feeding direction of the loaded part, the solid blank can be processed into a shell with a blind hole and a desired outer wall shape using the method.

[0086] From the above analysis, it can be seen that since this method uses a multi-stage hammer combination to perform continuous pulsed radial local loading on different parts of the blank, at the same time, the positions and speeds of each hammer in each hammer combination are different, which puts forward higher requirements for controlling the movement of the hammers in each hammer, especially when the pulse frequency is high, how to achieve high-frequency pulse loading between each hammer is an important factor to ensure the forming effect. Obviously, at this time, the conventional drive scheme is used to control each hammer separately through multiple motors, which will require complex programming and multiple sets of motors, resulting in a significant increase in equipment structure, control difficulty and economic cost.

[0087] The forming method relies on radial loading equipment to realize radial loading of combined array hammers. At the same time, relative rotational motion needs to be generated between the hammers and the blank. The implementation methods include but are not limited to the following forms:

[0088] Rotary forging equipment: the hammer head rotates, and the blank is only fed axially without rotating, or rotates in the reverse direction;

[0089] Radial forging equipment: The hammer head is radially loaded and does not rotate, and the billet is axially fed and rotated.

[0090] To this end, in some preferred embodiments of the present application, a mold device that can implement the forming method is also provided for illustration, and the mold device is used to drive the hammer head assembly of each stage to accurately perform pulsed continuous radial local loading on the blank. The mold device includes at least two stages of hammer head assemblies distributed in sequence along the axial feed direction of the blank, an annular chuck 1, and a driving component, such as Figure 7-Figure 14As shown, each level of hammer head combination includes at least two hammer heads 3 distributed along the circumferential direction and capable of radial reciprocating motion, a feed hole 11 is opened at the central axis of the annular chuck 1, which is used to feed the blank along the axial direction of the feed hole 11, and at least two guide grooves 12 are provided on the annular chuck 1, at least two of the guide grooves 12 are distributed along the circumferential direction of the annular chuck 1 and radially penetrate the inner and outer walls thereof, at least two of the hammer heads 3 are respectively accommodated in each of the guide grooves 12, and the guide grooves 12 are used to guide the radial movement path of each hammer head 3 one by one.

[0091] Furthermore, each of the hammer heads 3 has a working surface 301 facing the axis of the feed hole 11, and at least a portion of the other end radially protrudes from the outer wall of the annular chuck 1, and is connected to the annular chuck 1 through an elastic reset member 5, and the elastic reset member 5 is used to elastically reset the hammer head 3 radially outward; the driving component is arranged on the outside of the annular chuck 1 and contacts with the radially protruding portion of the hammer head 3, and the driving component drives the hammer head 3 to move radially in the guide groove 12 until the working surface 301 of the hammer head 3 moves to protrude from the inner wall of the annular chuck 1.

[0092] When each hammer 3 included in any one-stage hammer combination is at the position with the smallest radial distance from the axis of the feed hole 11, the working surface 301 of the hammer 3 forms the outer contour size of the blank at the hammer combination of this stage along the circumferential direction. By axially grading the radial blank and co-optimizing the axial / circumferential distribution (axial width / spacing, circumferential distribution / angle relationship, etc.) of the multi-stage hammer combination, the radial load and loading frequency of different loading areas can be regulated in stages. It can be applied to the plastic forming and manufacturing of different shells, pipes, and rod components with equal diameter / non-equal diameter and equal wall thickness / non-equal wall thickness, and the cross-sectional shape of the component includes different structures such as rotating body / non-rotating body.

[0093] In some preferred embodiments, along the axial feeding direction of the blank, the axial cross-section of the outer contour dimensions of each level of hammer head combination shrinks continuously or stepwise, so that as the feeding process of the blank progresses, the radial dimension of the forged part continues to shrink.

[0094] In some preferred embodiments, the number of hammer heads 3 included in each level of hammer head combination is unequal or equal. When the number of hammer heads 3 included in each level of hammer head combination is equal, the circumferential distribution of each hammer head 3 included in any level of hammer head combination is the same as or staggered with the circumferential distribution of each hammer head 3 included in the adjacent hammer head combination, which is used to improve the uneven deformation of the blank, which is prone to causing instability and wrinkling and other defects.

[0095] Furthermore, the circumferential distribution of each hammer head 3 contained in each level of hammer head combination deflects to the same rotation direction as the number of levels increases, so as to avoid the problems of large-sized billets having large changes in wall thickness and radial dimensions at different axial positions, large differences in stress / strain distribution states, and uneven overall deformation, which can easily lead to defects such as instability and wrinkling.

[0096] In some preferred embodiments, the upper limit of the number of graded groups and the axial length of the hammer head 3 increases with the increase of the radial dimension change rate of its working surface 301, that is, the larger the curvature of the working surface 301 toward the feed hole 11, the larger the axial length of the hammer head 3. The multi-stage hammer head combination adopts high-frequency pulse small deformation loading, uniform discrete shrinking deformation and large deformation, thereby improving the shrinking forming limit.

[0097] Furthermore, the frequency of the radial reciprocating motion of the hammer head 3 increases with the increase in the radial size change rate of its working surface, that is, along the axial direction of the blank, the greater the degree of curvature of the surface of the blank to be forged, the greater the radial displacement distance of the hammer head 3 along the annular chuck 1, and accordingly, the forging frequency will also increase, making the curved surface at the forged location smoother.

[0098] In some preferred embodiments, a driving surface 302 is provided at one end of the hammer head 3 radially protruding from the outer wall of the annular chuck 1, and the driving surface 302 faces away from the working surface 301, and is arranged in an arc surface with a high top middle part and low ends, so that the radial depression amount and displacement curve of each group of hammer heads 3 can be adjusted by designing different arc surface angles and asymmetric arc surfaces, thereby optimizing the motion matching degree of the designed combined array hammer heads.

[0099] In some preferred embodiments, in order to enable the hammer head 3 to better forge a desired forming surface and extend its service life, the present embodiment further optimizes the structure of the hammer head 3, such as Fig.12 As shown, the hammer 3 includes a hammer slider 31, a hammer member 32, a torsion spring 33 and a gasket 34. The side of the hammer member 32 facing the feed hole 11 is a working surface 301, and the side of the hammer slider 31 facing away from the feed hole 11 is a driving surface. The hammer slider 31 and the hammer member 32 are elastically connected along the radial direction of the annular chuck 1 through the torsion spring 33. The gasket 34 is arranged between the connecting surfaces of the hammer slider 31 and the hammer member 32 to provide a buffer for the relative movement between the hammer slider 31 and the hammer member 32.

[0100] In some preferred embodiments, in order to reduce the friction force when the hammer head 3 and the annular chuck 1 move relative to each other, the mold device further includes a slide groove 4, such as Fig.13As shown, the slide groove 4 is composed of a first structure 41 and a second structure 42, and also includes a slide groove 4, the slide groove 4 is composed of a first structure 41 and a second structure 42, the second structure 42 is connected to the end of the first structure 41, and extends outward along the circumference of the annular chuck 1, the first structure 41 is accommodated in the guide groove 12, the second structure 42 is limited between the outer wall of the annular chuck 1 and the radially protruding part of the hammer head 3, and the elastic reset member 5 is connected to the hammer head 3 through the second structure 42.

[0101] Specifically, Fig.11 As shown, the annular chuck 1 also includes a groove 13, and the groove 13 is arranged on the outer wall of the annular chuck 1 along the circumference of the annular chuck 1, and is connected with the guide groove 12, and the end of the second structure 42 and the driving surface 302 are both limited in the groove 13, and when the hammer head 3 is at the position with the smallest radial distance from the axis of the blank, the outer wall of the annular chuck 1 and the driving surface 302 have a smooth transition, so that the driving device drives the hammer head 3 to move radially by rotation.

[0102] In some preferred embodiments, the annular chuck 1 also includes an accommodating blind hole 14, and each groove 13 is provided with at least two accommodating blind holes 14, at least two of the accommodating blind holes 14 are arranged on both sides of the guide groove 12, and one end is connected with the groove 13, and the accommodating blind hole 14 is used to accommodate the elastic reset member 5.

[0103] In some preferred embodiments, a through hole structure corresponding to the accommodating blind hole 14 is provided on the second structure 42, one end of the elastic reset member 5 passes through the through hole structure of the second structure 42, and is connected to the radially protruding portion of the hammer head slider 31, and the elastic reset member 5 is used to elastically reset the hammer head radially outward.

[0104] In some preferred embodiments, the elastic return member 5 includes an elastic material with elastic restoring force such as a spring, a rubber band, a balloon, etc. Of course, since the impact force of the hammer head 3 in this embodiment is relatively large during the forging process, a spring is more suitable for this embodiment, but the spring in this embodiment does not limit the form of the elastic return member 5.

[0105] In some preferred embodiments, the driving assembly includes at least one roller driving device 2 and a driving motor, wherein the roller driving device 2 is covered on the outside of the annular chuck 1, and each roller of the roller driving device 2 is in contact with the outer wall of the annular chuck 1, and the driving motor is used to drive the annular chuck 1 and each roller in the roller driving device 2 to perform circumferential relative movement. When the roller driving device 2 rotates, the roller driving device 2 presses over the driving surface 302 of the hammer head 3, thereby driving the hammer head 3 to move toward the feed hole 11 to forge the blank.

[0106] In some preferred embodiments, the roller drive device 2 is arranged corresponding to the hammer head combination of each stage, and the diameter or number of the rollers of each roller drive device 2 is determined by the average curvature of the axial projection line of each hammer head working surface 301 in its corresponding hammer head combination, that is, if the amplitude of the radial displacement of the hammer head 3 is small, the diameter of the roller can be set to a small size, and accordingly, the number of rollers will increase; if the frequency of the radial displacement of the hammer head 3 increases, the diameter of the roller can be set to a large size.

[0107] In some preferred embodiments, the number of the annular chucks 1 is greater than 1, and two adjacent annular chucks 1 are connected integrally along the axial direction, or are connected separately along the axial direction, and each of the separately connected annular chucks 1 rotates synchronously along the circumferential direction, and the integrally connected annular chucks 1 are used to accommodate no more than two levels of hammer head combinations, so as to realize axial step-by-step grading of the mold device.

[0108] In some preferred embodiments, each layer of the annular chuck 1 is circumferentially positioned by a key / keyway and axially fixedly connected by bolts.

[0109] In some preferred embodiments, in order to facilitate the positioning of the hammer head 3 in the guide groove 12 and the displacement path, the mold device also includes a mounting cover 10, and the mounting cover 10 is installed on the outer side of the annular chuck 1, so that the mounting cover 10 can serve as a side wall of the guide groove 12 to position the hammer head 3 in the guide groove 12 without axial displacement.

[0110] The following is a detailed description of this application in conjunction with the specific process:

[0111] Each hammer head member 32 is rigidly connected to the hammer head slider 31 on the outside along the radial direction through a torsion spring 33. During the rotation of the annular chuck 1, the arc-shaped driving surface 302 of each hammer head slider 31 interacts with the roller of the roller drive device 2, thereby realizing a combined radial pulse loading motion. When the driving surface 302 at the top of the hammer head slider 31 rotates to the top of the roller, the radial maximum load of the hammer head 3 is reached. At this time, the hammer head 3 is at the minimum radial distance from the axis of the blank. Then, the centrifugal force of the rotation process and the elastic reset member 4 are used to reset the hammer head 3. At this time, the arc-shaped top of the driving surface 302 rotates to the roller gap, and the hammer head 3 is at the maximum radial distance from the axis of the blank.

[0112] On this basis, since at least two levels of hammer head combinations are provided, the circumferential distribution of each hammer head 3 contained in each level of hammer head combination deflects to the same rotation direction as the number of levels increases, so that when the driving assembly drives the annular chuck to rotate, at least two levels of hammer head combinations rotate and work in the same direction, and each hammer head forges the blank in the radial direction, ensuring that each forging surface of the blank is hammered more evenly and the force is more balanced under the action of radial movement and circumferential rotational movement.

[0113] In some preferred embodiments, a combined pulse continuous radial local loading forming method specifically comprises the following steps:

[0114] Step 1: Using a thin-walled tube designed according to a forging as an initial blank, design and manufacture an array hammer suitable for combined pulse radial local loading;

[0115] Step 2: Assemble an array of hammers on the radial loading forming equipment to form at least two levels of hammer combinations continuously arranged along the axial direction, preheat the working surface and core rod of each level of hammer combination before forming, or adopt cold forming (without preheating) or without setting the core rod according to actual process requirements;

[0116] Step 3: Preheat the tube to the deformation temperature. The non-uniform temperature field of the billet can be set according to the actual process requirements, or cold forming can be performed according to the material deformation characteristics of the billet;

[0117] Step 4: Fix the blank on the clamping chuck and adjust the blank until its axis coincides with the axis of the combined pulse local loading deformation zone;

[0118] Step 5: Start the radial loading forming equipment to perform high-frequency combined pulse local loading;

[0119] Step 6: The blank is continuously fed into the high-frequency pulse loading area along the axial direction, and the radial size of the front wall of the blank is reduced; then the blank is continuously fed along the axial direction, the deformed area continues to extend toward the front end, and the front end of the undeformed area continuously enters the loading area, achieving overall uniform deformation to obtain a forging;

[0120] Step 7: Reversely eject the formed forging from the feed end.

[0121] Furthermore, the component material of the blank includes steel, aluminum alloy, titanium alloy, magnesium alloy, and a composite material with any one of these metal materials as a matrix.

[0122] The above-mentioned operation steps are described in detail below in conjunction with specific embodiments. The specific forming method includes the following steps. Specific implementation method one:

[0124] Step 1: Assembly work

[0125] A three-stage combined array hammer head is designed for a forging with a maximum diameter of 300 mm, a minimum diameter of 160 mm at the necking, a maximum wall thickness of 30 mm, a minimum wall thickness of 15 mm, and an axial distance of 700 mm in the necking diameter reducing section.

[0126] Design a special rotary forging device to drive the combined pulse-loaded hammer to radially load and rotate. Assemble the array hammers, the die device includes at least two levels of hammer assemblies, an annular chuck 1, a roller drive device 2 and a drive motor, which are sequentially distributed along the axial feed direction of the blank. Each level of the hammer assembly includes at least two hammers 3 distributed along the circumference and capable of radial reciprocating motion. The number of hammers 3 included in each level of the hammer assembly is different. Each hammer 3 is distributed along the circumference of the annular chuck 1 and radially penetrates the inner and outer walls of the annular chuck 1. At least a part of one end of the hammer 3 protrudes radially from the outer wall of the annular chuck 1 and is connected to the annular chuck 1 through an elastic reset member. The other end of the hammer 3 has an axial working surface facing the feed hole 11, so that each hammer 3 in the hammer assembly at each level is radially limited by the annular chuck 1 and can rotate synchronously along the axial direction driven by the annular chuck.

[0127] When each hammer included in any one-stage hammer combination is at the position with the smallest radial distance from the axis of the feed hole 11, its working surface forms the outer contour dimension of the blank at the hammer combination of this stage along the circumferential direction, and the axial section of the outer contour dimension shrinks stepwise along the axial feed direction;

[0128] The roller drive device 2 is coated on the outside of the annular chuck 1, and each roller of the roller drive device 2 is in contact with the outer wall of the annular chuck 1. The drive motor is electrically connected to the annular chuck 1, so that when the drive motor drives the annular chuck 1 to rotate, each hammer head in the hammer head assembly can perform pulsed continuous radial loading on the tube blank under the action of the rollers in the roller drive device.

[0129] Step 2: Preheating and clamping of blanks

[0130] The initial blank is a thin-walled tube with a large aspect ratio and a large diameter-thickness ratio, with an initial diameter of 200 mm, a wall thickness of 12 mm, and a length of 800 mm. The high-frequency induction heating device is used to locally heat the blank forming section. After heating, the clamping end of the propulsion device is clamped at the end of the tube blank and adjusted so that the axis of the tube blank coincides with the center line of the feed hole 11 of the mold device.

[0131] Step 3: Start the forming device

[0132] The propulsion unit and the driving motor are started, and the driving motor drives the annular chuck 1 to rotate, while the propulsion unit pushes the tube blank to continuously feed along the feeding direction at a predetermined speed.

[0133] Step 4: Forming device working

[0134] In the axial feeding direction, the pusher continuously pushes the tube into the feed hole 11. The distance and frequency of the radial reciprocating motion of the hammers in each level of hammer assembly are different. The feed rate of the pusher gradually slows down according to the accumulation of deformation in the forming section. The tube passes through the outer contour dimensions of each level of hammer assembly in turn. Under the high-frequency hammering action of the first-level hammer and the second-level hammer, the tube undergoes plastic deformation with radial dimension reduction and wall thickness increase.

[0135] At this time, the outer wall of the tube billet passes through each level of hammer head combination in turn, and the hammer head 3 in each level of hammer head combination performs pulsed radial local loading on the outer wall of the tube billet. As the tube billet continues to be fed, the locally deformed area of ​​the tube billet continues to extend toward the next level of hammer head combination, and the undeformed area continues to be fed continuously.

[0136] Step 5: Get the forging

[0137] When the tube billet is pushed to the last stage of the hammer assembly and the forging completes the axial distance required for the forming section, the formed structural part is withdrawn from the feed end of the die device in the opposite direction of the feed direction to obtain the forging.

[0138] In some preferred embodiments, the axial distance of the combined pulse loading array mold hammer forming section is greater than or equal to 800 mm.

[0139] In some preferred embodiments, the diameter of the tube blank is less than or equal to 400 mm, and accordingly, the outer diameter of the annular chuck 1 is greater than or equal to 1 meter, and the outer diameter of the roller drive device 2 is greater than or equal to 1.4 meters.

[0140] In some preferred embodiments, the rotation speed of the annular chuck 1 driven by the motor is greater than or equal to 20 r / min, and the pulse loading frequency of each hammer 3 in the hammer assembly is greater than or equal to 600 times / min.

[0141] In some preferred embodiments, in order to achieve different radial reciprocating distances of the hammers in each level of hammer assembly, the size of the rollers in the roller drive device 2 and the arc size of the driving surface of the hammer 302 can be modified. For example, one hammer 3 corresponds to a plurality of small-sized rollers, and the other hammer 3 corresponds to a large-sized roller. Accordingly, when the small-sized rollers pass through the driving surface of the hammer 3, the radial reciprocating distance of the hammer 3 will be reduced. Specific implementation method 2:

[0143] Step 1: Assembly work

[0144] A four-section combined array hammer is designed for a forging with a maximum diameter of 400 mm, a minimum diameter of 180 mm at the necking, a maximum wall thickness of 40 mm, a minimum wall thickness of 20 mm, and an axial distance of 800 mm in the necking diameter-changing section.

[0145] A special radial forging equipment is designed, the principle of which is that the hammer is loaded radially without rotating, and rotates during the feeding of the billet. An array-type hammer die is assembled, and multiple sets of eccentric shaft mechanical structures are used to drive the combined hammer to reciprocate radially. The eccentricity of the eccentric shaft is changed to adjust the different radial loads and loading frequencies of the multi-stage hammers. Similarly, when each hammer included in any one-stage hammer combination is at the position with the smallest radial distance from the axis of the feed hole 11, its working surface forms the outer contour dimensions of the billet at this stage of the hammer combination along the circumferential direction, and the axial section of the outer contour dimensions shrinks stepwise along the axial feeding direction.

[0146] Step 2: Preheating and clamping of blanks

[0147] The initial blank is a thin-walled tube with a large aspect ratio and a large diameter-thickness ratio, with an initial diameter of 400 mm, a wall thickness of 20 mm, and a length of 1.4 m. A high-frequency induction heating device is used to locally heat the blank forming section. After heating, the clamping end of the propulsion device is clamped at the end of the tube blank and adjusted so that the axis of the tube blank coincides with the center line of the feed hole 11 of the mold device.

[0148] Step 3: Start the forming device

[0149] The propulsion unit and the drive motor are started, and the drive motor controls multiple sets of eccentric shaft mechanical structures to drive multiple sets of hammers to reciprocate radially. The propulsion unit pushes the tube billet to continuously feed at a predetermined speed along the feeding direction, and drives the tube billet to continuously rotate at a predetermined speed during the axial feeding process.

[0150] Step 4: Forming device working

[0151] Along the axial feeding direction, the propulsion unit continuously pushes the tube blank into the feed hole 11, and the distance and frequency of the radial reciprocating motion of the hammers in each level of hammer head combination are different. The feeding rate of the propulsion unit gradually slows down with the accumulated deformation of the forming section. The tube blank passes through the outer contour dimensions of each level of hammer head combination in sequence. Under the high-frequency and local small deformation hammering action of the first-level hammer head, the second-level hammer head, the third-level hammer head and the fourth-level hammer head, the tube blank undergoes plastic deformation with radial size reduction and wall thickness increase.

[0152] At this time, the outer wall of the tube billet passes through each level of hammer head combination in turn, and the hammer head 3 in each level of hammer head combination performs pulsed radial local loading on the outer wall of the tube billet. As the tube billet continues to be fed, the locally deformed area of ​​the tube billet continues to extend toward the next level of hammer head combination, and the undeformed area continues to be fed continuously.

[0153] Step 5: Get the forging

[0154] When the tube billet is pushed to the last stage of the hammer assembly and the forging completes the axial distance required for the forming section, the formed structural part is withdrawn from the feed end of the die device in the opposite direction of the feed direction to obtain the forging.

[0155] The above is a detailed introduction to the specific implementation methods of the present application. For those skilled in the art, several improvements and modifications may be made to the present application without departing from the principles of the present application. These improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A combined pulse local loading continuous shrinking forming method, used for loading and forming a blank fed along the axial direction, comprising the following operations: Continuously feed the blank in the axial direction, and Using each hammer in at least two-stage hammer combinations arranged continuously in the axial direction to perform pulsed radial local loading on the blank being continuously fed; It is characterized in that When each hammer included in any one-stage hammer combination is at the position with the smallest radial distance from the blank, its working surface forms the outer contour size of the blank at the hammer combination of this stage along the circumferential direction, and Each hammer in each stage of the hammer assembly performs pulsed radial local loading on the outer wall of the blank through radial reciprocating motion; The axial length of the hammers in each level of hammer assembly is determined based on the radial dimension change rate of the working surface.

2. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: The axial cross-section of the outer contour dimensions of each stage of the hammer head combination shrinks continuously or stepwise along the axial feeding direction of the blank.

3. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: The blank has a shell shape or a non-shell solid shape.

4. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: When the blank has a solid form other than a shell, the following steps are further included: A mandrel is used to abut against the end face of the blank in its feeding direction and fix the position of the mandrel, or the mandrel is used to abut against the end face of the blank in its feeding direction and the mandrel is continuously fed in a direction opposite to the feeding direction of the blank, wherein the mandrel is parallel to the axis of the blank.

5. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: The number of hammers contained in each level of hammer combination is unequal or equal.

6. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: When the number of hammers included in each level of hammer head combination is equal, the circumferential distribution of the hammers included in any level of hammer head combination is the same as or staggered with the circumferential distribution of the hammers included in the adjacent hammer head combination.

7. The combined pulse local loading continuous shrinking forming method according to claim 4, characterized in that: The circumferential distribution of each hammer head included in each level of hammer head combination deflects toward the same rotation direction as the number of levels increases.

8. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: The upper limit of the number of classification groups and the axial length of the hammer heads in each level of hammer head combination increases with the increase of the radial dimension change rate of the working surface; The multi-stage hammer combination adopts high-frequency pulse small deformation loading.

9. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: The radial load and / or frequency of the hammers in each stage of the hammer combination are the same and / or different.

10. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: The method also includes the step of preheating the blank.

11. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: The specific steps include: Step 1: Using a thin-walled tube designed according to a forging as an initial blank, design and manufacture an array hammer suitable for combined pulse radial local loading; Step 2: Assemble an array of hammers on the radial loading forming equipment to form at least two levels of hammer combinations continuously arranged along the axial direction, preheat the working surface and core rod of each level of hammer combination before forming, or adopt cold forming (without preheating) or without setting the core rod according to actual process requirements; Step 3: Preheat the tube to the deformation temperature. The non-uniform temperature field of the billet can be set according to the actual process requirements, or cold forming can be performed according to the material deformation characteristics of the billet; Step 4: Fix the blank on the clamping chuck and adjust the blank until its axis coincides with the axis of the combined pulse local loading deformation zone; Step 5: Start the radial loading forming equipment to perform high-frequency combined pulse local loading; Step 6: The blank is continuously fed into the high-frequency pulse loading area along the axial direction, and the radial size of the front wall of the blank is reduced; then the blank is continuously fed along the axial direction, the deformed area continues to extend toward the front end, and the front end of the undeformed area continuously enters the loading area, achieving overall uniform deformation to obtain a forging; Step 7: Reversely eject the formed forging from the feed end.

12. The combined pulse local loading continuous shrinking forming method according to claim 1, characterized in that: The component materials of the blank include steel, aluminum alloy, titanium alloy, magnesium alloy, and composite materials with any one of these metal materials as a matrix.

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