CN118023454A - Rotary forging processing method of magnesium alloy bar and small-diameter magnesium alloy bar - Google Patents
Rotary forging processing method of magnesium alloy bar and small-diameter magnesium alloy bar Download PDFInfo
- Publication number
- CN118023454A CN118023454A CN202410148547.XA CN202410148547A CN118023454A CN 118023454 A CN118023454 A CN 118023454A CN 202410148547 A CN202410148547 A CN 202410148547A CN 118023454 A CN118023454 A CN 118023454A
- Authority
- CN
- China
- Prior art keywords
- magnesium alloy
- alloy bar
- rotary forging
- die
- pass
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000005242 forging Methods 0.000 title claims abstract description 137
- 229910000861 Mg alloy Inorganic materials 0.000 title claims abstract description 129
- 238000003672 processing method Methods 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 58
- 230000008569 process Effects 0.000 claims abstract description 42
- 238000000227 grinding Methods 0.000 claims abstract description 28
- 239000002994 raw material Substances 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- 239000013078 crystal Substances 0.000 claims abstract description 15
- 230000005484 gravity Effects 0.000 claims description 8
- 238000005485 electric heating Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 description 12
- 238000004321 preservation Methods 0.000 description 10
- 239000000956 alloy Substances 0.000 description 6
- 238000007599 discharging Methods 0.000 description 6
- 230000007547 defect Effects 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 239000007943 implant Substances 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 230000003746 surface roughness Effects 0.000 description 3
- 229910009378 Zn Ca Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000000149 penetrating effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J7/00—Hammers; Forging machines with hammers or die jaws acting by impact
- B21J7/02—Special design or construction
- B21J7/14—Forging machines working with several hammers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
- B21C37/045—Manufacture of wire or bars with particular section or properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D3/00—Straightening or restoring form of metal rods, metal tubes, metal profiles, or specific articles made therefrom, whether or not in combination with sheet metal parts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/002—Hybrid process, e.g. forging following casting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Forging (AREA)
Abstract
The invention relates to a rotary forging processing method of a magnesium alloy bar, which is characterized by comprising the following steps: and (3) carrying out multi-pass four-die rotary forging, straightening bars and removing the superfine crystal hard layer. The multi-pass four-die rotary swaging comprises multiple single-pass four-die rotary swaging which is sequentially carried out, and the single-pass four-die rotary swaging comprises the steps of heating and preserving heat of a raw material magnesium alloy bar by utilizing a feeding device and then feeding the raw material magnesium alloy bar into a four-die rotary swaging machine for four-die rotary swaging. Performing multi-pass four-die rotary forging to obtain a rotary forging magnesium alloy bar with the diameter of 4-8mm and the surface provided with an ultrafine grain hard layer; straightening the rotary forging magnesium alloy bar by adopting a straightener under the condition of heating to obtain a straightened magnesium alloy bar; finally, adopting a multipass grinding process to remove the superfine crystal hard layer on the surface of the straightened magnesium alloy bar, and finally obtaining the small-diameter magnesium alloy bar with the diameter of 3-7 mm.
Description
Technical Field
The invention relates to the field of alloy material manufacturing, in particular to a rotary forging processing method of a magnesium alloy bar and the magnesium alloy bar manufactured by the processing method.
Background
The magnesium alloy material has excellent degradability and good biocompatibility, and the human body implant taking the magnesium alloy as the material gradually shows important strategic positions. However, the mechanical properties of the magnesium alloy bar formed by casting and extrusion cannot meet the strength requirements of related human implants, so that the magnesium alloy material implants are degraded too quickly after being implanted into a human body, and the risk of early functional failure is caused.
In the prior art, a screw type feeding device is adopted to uniformly feed a magnesium alloy extrusion bar into two forging dies of a rotary forging machine, and multi-pass rotary forging processing is carried out under the preset rotary forging temperature, single-pass deformation and preset rotary forging rate. The high-frequency pulse is loaded on the surface of the magnesium alloy bar, radial compressive stress is generated to gradually extend to the inside of the material, and dynamic recrystallization and plastic deformation are generated in the internal grain structure, so that the internal grain structure of the material is tiny and uniform, and the mechanical property of the material is improved.
However, the magnesium alloy material has poor room temperature deformability, and the defect of extremely rapid growth, hot cracking and the like of the internal grain structure of the material can be caused by the overhigh temperature; in addition, radial compressive stress mainly acts on the surface of the material in the rotary forging process, so that an obvious superfine crystal hard layer is easily formed on the surface of the bar, and the defects of surface cracking, peeling and the like occur in the rotary forging process; in addition, as the radial compressive stress is continuously applied in the rotary forging process, the internal stress of the material is continuously accumulated, and the straightness of the small-specification magnesium alloy bar is continuously deteriorated along with the rotary forging of multiple passes, so that the irreversible influence is caused for the subsequent product processing.
Therefore, when the medical magnesium alloy bar with small diameter (4-8 mm) is produced by rotary forging, the problems of poor straightness, easy formation of an ultrafine grain hard layer on the surface, increased surface defects and the like exist.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention provides a rotary forging processing method of magnesium alloy bars by a four-die rotary forging machine, which is characterized by comprising the following steps of
Multi-pass four-die swaging comprising:
Sequentially carrying out multiple single-pass four-die rotary forging, wherein the single-pass four-die rotary forging comprises the steps of heating and preserving heat of a raw material magnesium alloy bar by using a feeding device, and then conveying the raw material magnesium alloy bar into a four-die rotary forging machine for four-die rotary forging; a guide sleeve is arranged at the discharge end of a die cavity of the four-die rotary forging machine, so that raw material magnesium alloy bars passing through the four-die rotary forging machine pass through the guide sleeve;
wherein the raw material magnesium alloy bar in the first single-pass four-die rotary forging is a magnesium alloy bar blank with the diameter of 10-15 mm;
Performing multi-pass four-die rotary forging to obtain a rotary forging magnesium alloy bar with the diameter of 4-8mm and the surface provided with an ultrafine grain hard layer;
Straightening the bar, namely straightening the rotary forging magnesium alloy bar by adopting a straightener under the condition of heating to obtain a straightened magnesium alloy bar;
And removing the superfine crystal hard layer, and removing the superfine crystal hard layer on the surface of the straightened magnesium alloy bar by adopting a multipass grinding process to finally obtain the small-diameter magnesium alloy bar with the diameter of 3-7 mm.
Further, the rotary swaging processing method as described above, wherein in the multi-pass four-die rotary swaging process, a total of 3 to 5 times of single-pass four-die rotary swaging is performed.
Further, according to the rotary forging processing method, the feeding device comprises a heating heat-preserving structure and a spiral feeding structure, and the heat-preserving temperature of the heating heat-preserving structure is 200-400 ℃.
Further, in the above-mentioned method for processing a single-pass four-die rotary forging, the heat preservation time of the magnesium alloy rod blank in the heating and heat preserving structure is 15-30 minutes, and then the heat preservation time in each single-pass four-die rotary forging is reduced compared with the heat preservation time in the last single-pass four-die rotary forging, and the reduced heat preservation time ranges from 25 min to 5min.
Further, according to the rotary forging processing method, the feeding end and the discharging end of the die cavity of the four-die rotary forging machine form conical channels, and the conical angle of the conical channel of the feeding end is larger than that of the conical channel of the discharging end, and the difference is 1-3 degrees.
Further, according to the rotary forging processing method, the guide sleeve comprises a guide pore canal penetrating through the guide sleeve, the radius of the guide pore canal is larger than the maximum radius of the discharge end, and the maximum difference is 0.5mm.
Further, according to the rotary forging processing method, the rotary forging speed of the four-die rotary forging machine is 0.5-3 m/min, the deformation of the single-pass four-die rotary forging is 15-45%, and the conical angle formed by the four dies of the four-die rotary forging machine is 5-15 degrees.
Further, according to the rotary forging processing method, the deformation of the obtained rotary forged magnesium alloy bar is less than or equal to 90% compared with the deformation of the magnesium alloy bar blank after the multi-pass four-die rotary forging.
Further, according to the rotary forging processing method, the straightening machine is an electric heating gravity straightening machine, the heating temperature is 150-300 ℃, the weight for gravity straightening is 40-100 kg, and the straightening time is 1-5 min. .
Further, in the rotary forging processing method, in the process of removing the superfine crystal hard layer, through the multi-pass grinding process, the accumulated grinding amount of the straightened magnesium alloy bar is less than or equal to 1mm, and the single grinding amount is 0.1-0.02 mm.
The invention also relates to a small-diameter magnesium alloy bar manufactured by the magnesium alloy bar rotary forging processing method, wherein the tensile strength of the small-diameter magnesium alloy bar can reach more than 320Mpa, and the yield strength can reach more than 300 Mpa.
The invention has the advantages that
1. According to the invention, the four-die rotary forging machine is adopted for rotary forging to produce the small-diameter magnesium alloy bar, and the stress distribution of the bar is more uniform in the rotary forging process due to the effect of the high-frequency loading four-way pressure stress, so that the stress concentration caused by the non-uniform pressure stress of the two-die rotary forging is effectively prevented, and the defects of peeling, cracks, poor surface roughness and the like of the bar in the rotary forging process are avoided; meanwhile, the guide sleeve is arranged at the discharge end of the die cavity of the four-die rotary forging machine, so that bar linearity difference caused by combined action of high-speed rotation centrifugal force and stress concentration of the rotary forging machine is effectively prevented.
2. According to the invention, the four-die rotary forging machine is adopted for rotary forging to produce the small-specification magnesium alloy bar, and due to the effect of high-frequency loading four-way pressure stress, the uniformity of the bar flowing along the circumferential direction can be effectively controlled, and the ovality error of the small-specification magnesium alloy bar can be controlled within 0-0.1 mm.
3. The tensile strength of the small-diameter magnesium alloy bar can reach more than 320Mpa, and the yield strength can reach more than 300 Mpa.
4. By adopting the magnesium alloy bar rotary forging method, straightening and multi-pass grinding can be carried out on the premise of not changing the internal grain structure, tensile strength, yield strength and other mechanical properties of the rotary forged magnesium alloy bar, and the straightness is less than 0.3mm/m.
5. According to the magnesium alloy bar rotary forging method, the superfine crystal hard layer generated by rotary forging for multiple passes on the surface of the straightened magnesium alloy bar can be removed through the multiple passes grinding process, so that the structural stability and subsequent processability of the bar are obviously improved.
Drawings
FIG. 1 is a flow chart of the method for swaging magnesium alloy bar material of the present invention.
FIG. 2 is a front view of the discharge end of the four-die rotary forging machine of the present invention
Fig. 3 is a cross-sectional view of a four die rotary forging machine die cavity of the present invention.
Fig. 4 is a cross-sectional view of the guide sleeve of the present invention.
FIG. 5 is a schematic view showing the internal structure of a swaged Mg-Zn-Ca alloy bar having a diameter of 5.5mm obtained by the multipass four-die swaging process of the present invention.
FIG. 6 is a schematic diagram of the internal structure of a 5mm diameter small diameter magnesium alloy bar obtained by removing the ultra-fine grain hard layer from a 5.5mm diameter swaged Mg-Zn-Ca alloy bar.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "one side", "one end", "one side", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, in the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
It is also to be understood that the terminology used in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
Various structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and their relative sizes, positional relationships shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required.
As shown in fig. 1, the method for swaging a magnesium alloy rod according to the present invention includes: and (3) straightening the magnesium alloy bar blank with the diameter of 10-15 mm after multi-pass four-die rotary forging, and finally removing the superfine crystal hard layer by multi-pass grinding to obtain the small-diameter magnesium alloy bar with the diameter of 3-7 mm.
The multi-pass four-die rotary swaging process comprises a plurality of single-pass four-die rotary swaging processes which are sequentially carried out, and preferably 3-5 single-pass four-die rotary swaging processes are carried out. The single-pass secondary four-die rotary forging comprises the steps of heating and preserving heat of a raw material magnesium alloy bar by using a feeding device, and then conveying the raw material magnesium alloy bar into the four-die rotary forging machine for four-die rotary forging; and a guide sleeve is arranged at the discharge end of the die cavity of the four-die rotary forging machine, so that the raw material magnesium alloy bar passing through the four-die rotary forging machine passes through the guide sleeve.
In single-pass four-die rotary forging, the feeding device comprises a heating heat-preserving structure and a spiral feeding structure. The heat preservation temperature of the heating heat preservation structure is 200-400 ℃.
In the first single-pass four-die rotary forging process, the heat preservation time of the magnesium alloy bar blank serving as the raw material magnesium alloy bar in the heating heat preservation structure is 15-30min. With the four-die rotary forging process, the heat preservation time can be shortened with the diameter reduction of the raw material magnesium alloy bar. Except the first single-pass four-die rotary forging process, the heat preservation time in the other four-die rotary forging processes is reduced by 25-5min compared with that in the last four-die rotary forging process
As shown in fig. 2 and 3, the four die rotary forging machine includes four forging dies 1. A cavity 2 having a circular cross section is formed in the middle of the four forging dies 1. The die cavity 2 comprises a feeding end and a discharging end. The feeding end and the discharging end of the die cavity 2 form conical channels (21, 22), and the conical angle of the conical channel 21 at the feeding end is larger than the conical angle of the conical channel 22 at the discharging end, and the difference is 1-3 degrees. Further the conical angle of the conical channel 21 of the feed end is 5-15. By matching with the four-die rotary forging machine lubricating system, the friction resistance of feeding can be effectively reduced, and the spiral feeding is easier. As shown in fig. 4, the guide sleeve in the invention is a hollow round tube with the length of 300-600 mm, and comprises a guide pore canal 3 penetrating through the guide sleeve and a guide inlet 4 positioned at one end of the guide sleeve and communicated with the guide pore canal 3, wherein the guide inlet 4 is communicated with a conical channel 22 at the discharge end, and when a raw material magnesium alloy bar is subjected to rotary forging by a four-die rotary forging machine, the raw material magnesium alloy bar directly enters the guide sleeve.
Preferably, the diameter of the guiding hole 3 is 4-21 mm, and is larger than the maximum diameter of the conical channel 22 at the discharging end, and the difference of the radius is 0.5mm at the maximum. Therefore, before the raw material magnesium alloy bar enters the four-die rotary forging machine, a proper guide sleeve is required to be selected according to the shape of the die cavity 2, so that the problem that the straightness of the magnesium alloy bar is poor due to the combined action of the high-speed rotation centrifugal force and the stress concentration of the rotary forging machine can be effectively prevented, and the straightness of the raw material magnesium alloy bar and the rotary-forged magnesium alloy bar after rotary forging is smaller than 1mm/m.
Preferably, the guiding inlet 4 is a conical channel, and the conical angle of the guiding inlet 4 is 30-60 degrees, so that the raw magnesium alloy bar can enter the guiding pore canal 3 conveniently.
Preferably, the four forging dies 1 of the four-die rotary forging machine are provided with gaskets with the precision of 0.05mm, so that the precision of deformation among each pass can be more effectively controlled, and the error between the theoretical deformation and the actual deformation among each pass is smaller than 0.05mm.
In single-pass four-die rotary forging, the heat-preserving raw material magnesium alloy bar is conveyed into a rotary forging die hole of a four-die rotary forging machine through the spiral feeding structure to be subjected to four-die rotary forging, and the rotary forging speed of the four-die rotary forging machine is 0.5-3 m/min. The deformation of the raw material magnesium alloy bar after the single-pass four-die rotary forging is 15-45%.
After one single-pass four-die rotary forging is completed, the forging die with smaller die cavity aperture and the corresponding guide sleeve are required to be replaced, and then the next single-pass four-die rotary forging is performed. The multi-pass four-die rotary forging makes the internal grain structure of the rotary forging bar uniform and tiny through four-way compressive stress and high-frequency pulse loading. After 3-5 single-pass four-die rotary forging, the rotary forging magnesium alloy bar with the diameter of 4-8 mm and the surface provided with the superfine crystal hard layer is obtained. As shown in fig. 2, the internal grain structure of the rotary forging magnesium alloy bar comprises a homogeneous layer 1 and an ultra-fine grain hard layer 2, and the rotary forging magnesium alloy bar is compared with the magnesium alloy bar blank, and the deformation amount is less than or equal to 90%.
The rod straightening is to straighten the rotary forging magnesium alloy rod by a straightener under the premise of heating and not damaging the internal grain structure and mechanical property of the rotary forging magnesium alloy rod, so as to obtain the straightened magnesium alloy rod with straightness less than 0.5 mm/m. Wherein the mechanical properties include tensile strength, yield strength, and the like.
And removing the superfine crystal hard layer by carrying out a multi-pass grinding process on the straightened magnesium alloy bar. The multi-pass grinding process comprises a plurality of single-pass grinding processes, wherein the grinding amount of the single-pass grinding process is 0.1-0.02 mm, and the accumulated grinding amount of the multi-pass grinding process is not more than 1mm. Finally removing the superfine hard layer 2 through a multi-pass grinding process to obtain the small-diameter magnesium alloy bar with the diameter of 3-7 mm and only the homogeneous layer 1, as shown in figure 3.
The superfine crystal hard layer is removed to improve the processability of subsequent products and the internal structure stability of the small-diameter magnesium alloy bar.
The invention also provides a small-diameter magnesium alloy bar manufactured by the rotary forging processing method of the magnesium alloy bar, which is characterized in that the diameter of the small-diameter magnesium alloy bar is 3-7 mm, the tensile strength can reach more than 320Mpa, and the yield strength can reach more than 300 Mpa.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The technical means used in the present invention are further described below by means of specific examples.
Examples
In the embodiment, the rotary forging processing method is used for processing the magnesium alloy rod blank with the diameter of 12 mm. As shown in fig. 2, in this embodiment, after 3 single-pass four-die swaging is sequentially performed on a magnesium alloy bar blank, a swaged magnesium alloy bar with an ultrafine grain hard layer 1 with a diameter of 5.5mm is obtained, and the deformation rate of the swaged magnesium alloy bar is 78.99% compared with that of the magnesium alloy bar blank. The process parameters of the multi-pass four-die rotary swaging of this example are shown in table 1:
Table 1 process parameters for multi-pass four-die swaging
In the embodiment, the bar straightening is to straighten the rotary forging magnesium alloy bar through an electric heating gravity straightener. The setting range of the straightening current of the electrothermal gravity straightener is 150-300A, the counterweight range is 40-100 kg, and the duration time of electrothermal gravity straightening is 1-5min. Specifically, the process parameters for straightening the bar in this example are shown in table 2:
Table 2 parameters of the electric heating gravity straightening process
The process for removing the superfine crystal hard layer in the embodiment is to perform 7-pass centerless grinding processing on the straightened magnesium alloy bar. The process parameters of the centerless grinding process are shown in table 3:
Table 3 technological parameters of centerless grinding process
In this embodiment, the removing the ultra-fine grain hard layer further includes polishing the surface of the magnesium alloy bar after the 7-pass centerless grinding process by using a polishing machine, wherein the polishing amount is 0.001-0.005 mm, and the surface roughness reaches 1500-2000 meshes.
Through multi-pass centerless grinding, an ultrafine grain hard embrittlement layer on the surface of the straightened bar is removed as shown in fig. 3, and a more uniform rotary forging structure in the interior is reserved, so that the structural stability and subsequent workability of the final small-diameter magnesium alloy bar are obviously improved.
A batch of small diameter magnesium alloy bars produced by the method of this example, from which three small diameter non-alloyed bars (material numbers 1, 2, 3, respectively) were arbitrarily selected, and their finished product sizes are shown in Table 4.
Table 4 finished bar size after centerless grinding
As shown in the table above, 10 points are selected on each small-diameter magnesium alloy bar for diameter measurement, wherein two measurement points in the same column on the same diameter reference numerals (1, 2,3, 4, 5) of the same material number represent measurement points which are 90 degrees apart on the same section of the same small-diameter magnesium alloy bar; and five-diameter marks in the same row of the same material number represent the same horizontal position of the same small-diameter magnesium alloy bar parallel to the axial direction at the positions of 5 diameter measuring points. Wherein max and min are the maximum value and the minimum value of 5 measuring points at the same horizontal position. The difference is the difference between max and min, and the average is the average of the diameters of 5 measurement points.
As can be seen from Table 4, the ovality error (i.e., the difference in diameter between two measurement points in the same column of the same material number) of the small-sized magnesium alloy bar is at most 0.001mm, and the straightness is at most 0.09mm/m.
The mechanical properties of 3 samples of the 3 small-diameter magnesium alloy bars are tested, and the test results are shown in table 5, wherein d0 is the average value of the diameters of the sections of the samples after fracture.
The invention has the advantages that
1. According to the invention, the four-die rotary forging machine is adopted for rotary forging to produce the small-diameter magnesium alloy bar, and the stress distribution of the bar is more uniform in the rotary forging process due to the effect of the high-frequency loading four-way pressure stress, so that the stress concentration caused by the non-uniform pressure stress of the two-die rotary forging is effectively prevented, and the defects of peeling, cracks, poor surface roughness and the like of the bar in the rotary forging process are avoided; meanwhile, the guide sleeve is arranged at the discharge end of the die cavity of the four-die rotary forging machine, so that bar linearity difference caused by combined action of high-speed rotation centrifugal force and stress concentration of the rotary forging machine is effectively prevented.
2. According to the invention, the four-die rotary forging machine is adopted for rotary forging to produce the small-specification magnesium alloy bar, and due to the effect of high-frequency loading four-way pressure stress, the uniformity of the bar flowing along the circumferential direction can be effectively controlled, and the ovality error of the small-specification magnesium alloy bar can be controlled within 0-0.1 mm.
3. The tensile strength of the small-diameter magnesium alloy bar can reach more than 320Mpa, and the yield strength can reach more than 300 Mpa.
4. By adopting the magnesium alloy bar rotary forging method, straightening and multi-pass grinding can be carried out on the premise of not changing the internal grain structure, tensile strength, yield strength and other mechanical properties of the rotary forged magnesium alloy bar, and the straightness is less than 0.3mm/m.
5. According to the magnesium alloy bar rotary forging method, the superfine crystal hard layer generated by rotary forging for multiple passes on the surface of the straightened magnesium alloy bar can be removed through the multiple passes grinding process, so that the structural stability and subsequent processability of the bar are obviously improved.
The present invention is not limited to the above-mentioned embodiments, but is capable of modification and variation in all embodiments without departing from the spirit and scope of the present invention.
Claims (10)
1. The rotary forging processing method of the magnesium alloy bar is characterized by comprising the following steps of:
Multi-pass four-die swaging comprising:
Sequentially carrying out multiple single-pass four-die rotary forging, wherein the single-pass four-die rotary forging comprises the steps of heating and preserving heat of a raw material magnesium alloy bar by using a feeding device, and then conveying the raw material magnesium alloy bar into a four-die rotary forging machine for four-die rotary forging; a guide sleeve is arranged at the discharge end of a die cavity of the four-die rotary forging machine, so that raw material magnesium alloy bars passing through the four-die rotary forging machine pass through the guide sleeve;
wherein the raw material magnesium alloy bar in the first single-pass four-die rotary forging is a magnesium alloy bar blank with the diameter of 10-15 mm;
Performing multi-pass four-die rotary forging to obtain a rotary forging magnesium alloy bar with the diameter of 4-8mm and the surface provided with an ultrafine grain hard layer;
Straightening the bar, namely straightening the rotary forging magnesium alloy bar by adopting a straightener under the condition of heating to obtain a straightened magnesium alloy bar;
And removing the superfine crystal hard layer, and removing the superfine crystal hard layer on the surface of the straightened magnesium alloy bar by adopting a multipass grinding process to finally obtain the small-diameter magnesium alloy bar with the diameter of 3-7 mm.
2. The method for rotary swaging a magnesium alloy rod according to claim 1, wherein the four-die rotary swaging is performed 3 to 5 times in a single-pass four-die rotary swaging process.
3. The method for rotary swaging a magnesium alloy rod according to claim 1, wherein the feeding device comprises a heating and heat-preserving structure and a spiral feeding structure, and the heat-preserving temperature of the heating and heat-preserving structure is 200-400 ℃.
4. A method of working a magnesium alloy bar according to claim 3, wherein the heat-retaining time of the magnesium alloy bar blank in the heating and heat-retaining structure is 15 to 30 minutes during the first single-pass four-die rotary forging, and the heat-retaining time in each subsequent single-pass four-die rotary forging is reduced from that in the previous single-pass four-die rotary forging by 25 to 5 minutes.
5. The method of claim 1, wherein the feed end and the discharge end of the die cavity of the four-die rotary forging machine each form a conical channel, and the conical angle of the conical channel at the feed end is greater than the conical angle of the conical channel at the discharge end by a difference of 1-3 °.
6. The method of claim 5, wherein the guide sleeve comprises a guide channel extending through the guide sleeve, the radius of the guide channel is greater than the maximum radius of the discharge end, and the difference is 0.5mm at the maximum.
7. The method for rotary swaging a magnesium alloy bar according to any one of claims 1 to 6, wherein the rotary swaging rate of the four-die rotary swaging machine is 0.5 to 3m/min, and the deformation amount of the single-pass four-die rotary swaging is 15 to 45%; and after the multi-pass four-die rotary forging, the deformation of the obtained rotary forged magnesium alloy bar is less than or equal to 90 percent compared with that of the magnesium alloy bar blank.
8. The method for rotary forging a magnesium alloy bar according to claim 7, wherein the straightener is an electric heating gravity straightener, the heating temperature is 150-300 ℃, the weight for gravity straightening is 40-100 kg, and the straightening time is 1-5 min.
9. The method for rotary forging a magnesium alloy bar according to claim 7, wherein the accumulated grinding amount of the straightened magnesium alloy bar is 1mm or less and the single grinding amount is 0.1 to 0.02mm through the multi-pass grinding process in the process of removing the ultra-fine grain hard layer.
10. A small-diameter magnesium alloy bar manufactured by the rotary forging processing method of the magnesium alloy bar according to claims 1-9, which is characterized in that the straightness of the small-diameter magnesium alloy bar is less than 0.3mm/m, the tensile strength can reach more than 320Mpa, and the yield strength can reach more than 300 Mpa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410148547.XA CN118023454A (en) | 2024-02-02 | 2024-02-02 | Rotary forging processing method of magnesium alloy bar and small-diameter magnesium alloy bar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410148547.XA CN118023454A (en) | 2024-02-02 | 2024-02-02 | Rotary forging processing method of magnesium alloy bar and small-diameter magnesium alloy bar |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118023454A true CN118023454A (en) | 2024-05-14 |
Family
ID=90996335
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410148547.XA Pending CN118023454A (en) | 2024-02-02 | 2024-02-02 | Rotary forging processing method of magnesium alloy bar and small-diameter magnesium alloy bar |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118023454A (en) |
-
2024
- 2024-02-02 CN CN202410148547.XA patent/CN118023454A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105970019B (en) | Medical high-strength degree Ti-6Al-4V alloy wires and its preparation process and application | |
| CN101579800B (en) | Warm/cold forging process for precision forgings with integrated long shafts and inner ball cages | |
| JP4798674B1 (en) | Rack bar and manufacturing method thereof | |
| CN109248980A (en) | The manufacturing method of GH4169 alloy bar material | |
| US20120079918A1 (en) | Method and device for producing longitudinal components of metal with helical grooves, in particular spiral drill bits or screws | |
| CN105414426B (en) | A kind of hot-swage method of kirsite small specification tube or bar | |
| CN111346931B (en) | Continuous processing method of nickel-titanium shape memory alloy square thin wire | |
| CN106826118B (en) | A kind of preparation method for manufacturing the medical titanium alloy bar of pedicle screw | |
| CN111593215A (en) | Preparation method of high-strength plastic-matched titanium alloy Kirschner wire | |
| CN113399461B (en) | Method for processing niobium-containing austenitic heat-resistant stainless steel round pipe billet | |
| CN112281025A (en) | TC4 titanium alloy wire and preparation method thereof | |
| US20200061689A1 (en) | Method for machining a workpiece made of a metallic material | |
| CN118023454A (en) | Rotary forging processing method of magnesium alloy bar and small-diameter magnesium alloy bar | |
| CN111889535A (en) | Preparation method of zirconium alloy bar | |
| CN106862863A (en) | A kind of preparation processing method of the ultra-thin titanium alloy shell of great diameter and long | |
| CN109482667B (en) | A kind of preparation method of strong mechanical performance austenitic stainless steel spring silk material | |
| CN104438430B (en) | A kind of titanium alloy abnormal shape capillary tubes processing method | |
| CN215916421U (en) | Golf club made of titanium alloy | |
| CN113000622B (en) | Manufacturing method of orthopedic implant connecting rod | |
| KR20100048256A (en) | Manufacturing method for wire rod dispensing with heat treatment, dies and dies arrangement for manufacturing the wire rod | |
| CN108006198A (en) | New-energy automobile reducer gear axis and its manufacturing process | |
| CN110814249B (en) | Forming method of stainless steel long pipe forging | |
| CN114535330B (en) | Method for preparing 15-5PH stainless steel pipe | |
| CN113444991B (en) | Titanium alloy golf club and preparation method of club body | |
| CN111716080A (en) | Preparation method of hollow needle material for medical products |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |