CN115846664A - Preparation method of hard alloy micropore wire-drawing die - Google Patents

Preparation method of hard alloy micropore wire-drawing die Download PDF

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Publication number
CN115846664A
CN115846664A CN202211697835.8A CN202211697835A CN115846664A CN 115846664 A CN115846664 A CN 115846664A CN 202211697835 A CN202211697835 A CN 202211697835A CN 115846664 A CN115846664 A CN 115846664A
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China
Prior art keywords
hard alloy
sintering
wire
drawing die
compact
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CN202211697835.8A
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Chinese (zh)
Inventor
吴建兵
黎铭
张亚军
朱振忠
彭英健
谢浩
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Zhuzhou Cemented Carbide Group Co Ltd
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Zhuzhou Cemented Carbide Group Co Ltd
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Priority to CN202211697835.8A priority Critical patent/CN115846664A/en
Publication of CN115846664A publication Critical patent/CN115846664A/en
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Abstract

The invention discloses a preparation method of a hard alloy micropore wire-drawing die, belonging to the technical field of hard alloy, comprising the following steps: pressing the hard alloy mixture, processing and sintering; the sintering is pressure sintering, and the gas pressure during sintering is 40-60 MPa. The invention processes the pressed compact of the hard alloy mixture, then presses and sinters the pressed compact, the precision of the size of the micropore wire-drawing die pressed compact after pressure sintering is high, the precision of the outer diameter and the height can reach the micron level, the finished product can be directly embedded without processing the outer diameter, the processing procedure is simple, and the time consumption is short.

Description

Preparation method of hard alloy micropore wire-drawing die
Technical Field
The invention belongs to the technical field of hard alloy, and particularly relates to a preparation method of a hard alloy micropore wire-drawing die.
Background
The hard alloy micropore wire drawing die mainly refers to a wire drawing die with the aperture of less than 1.0mm, and is mainly used for drawing various metal wires with smaller diameters, including tantalum wires, niobium wires, gem cutting wires, steel cords for tires and the like.
The precision requirement of the tire steel cord is very high, so the precision requirement of the micropore wire-drawing die is also very high. The allowable deviation of the outer diameter is +/-0.01 mm, the allowable tolerance of the inner diameter is-0.02 mm, and the allowable tolerance of the height is +/-0.05 mm, but when the traditional pressing and sintering method is adopted, the dimensional precision can not meet the requirements, finished product processing needs to be carried out after sintering, the dimensional precision can be achieved, the processing procedure is complex, the consumed time is long, and waste products such as edge falling are easily generated.
Therefore, the invention provides a preparation method of a hard alloy micropore wire-drawing die, which aims to solve the problems in the background technology.
Disclosure of Invention
The present invention is directed to a method of making a cemented carbide micro-porous die that addresses at least one of the problems and deficiencies set forth in the background above.
According to one aspect of the invention, a method for preparing a hard alloy micropore wire-drawing die is provided, which comprises the following steps:
pressing the hard alloy mixture, processing and sintering;
the sintering is pressure sintering, and the gas pressure during sintering is 40-60 MPa. When the pressure is too low, densification is difficult to be sufficiently completed during sintering, and excessively coarse pores are formed, while when the pressure is too high, excessive consumption of gas is caused.
According to an exemplary embodiment of the invention, the sintering temperature is 1370-1450 ℃, so that the compactness of the hard alloy mixture is better.
According to another exemplary embodiment of the invention, the sintering time is 40-60 min, so that the compactness of the cemented carbide mixture is better. If the time is too short, densification is difficult to complete fully during sintering, too large pores can be formed, and if the time is too long, abnormal growth of crystal grains can be caused, so that the impact resistance of the alloy is reduced, and the wear resistance of the alloy is reduced.
According to another exemplary embodiment of the invention, the preparing step of the cemented carbide mixture comprises:
and carrying out ball milling and mixing on the WC powder, the cobalt powder and the grain growth inhibitor, and then carrying out spray drying to obtain the hard alloy mixture.
According to another exemplary embodiment of the present invention, the grain growth inhibitor comprises VC and Cr 3 C 2 Wherein VC accounts for 25 to 35 percent, and Cr 3 C 2 65% -75%, and excessive inhibitors can affect the compactness of products, form excessive or oversized pores, and cause the reduction of the impact resistance of the alloy. If the amount of the inhibitor is too small, the growth of grains cannot be effectively inhibited, and abnormally large grains are formed.
According to another exemplary embodiment of the present invention, the WC powder has a particle size of 0.1 μm to 0.3 μm.
According to another exemplary embodiment of the invention, the cobalt content of the WC powder is 3% to 12%, too high or too low may affect the impact resistance of the cemented carbide mixture, too low may cause a decrease in the impact resistance of the product, and too high may cause a decrease in the abrasive wear resistance.
According to another exemplary embodiment of the present invention, the grain growth inhibitor accounts for 0.2% to 1.0% of the total volume of the grain growth inhibitor and the sum of the WC powder and the Co powder, and an excessive amount of the inhibitor affects the compactness of the product, forms pores, and causes a decrease in the impact resistance of the product. If the amount of the inhibitor is too small, the growth of grains cannot be effectively inhibited, and abnormally large grains are formed. .
According to another exemplary embodiment of the present invention, when the mixing is performed by using a ball mill, the ball-to-material ratio is 5; if the ball-to-material ratio is too low, the material storage amount is too large, the over-crushing phenomenon is increased, and the ball-milling efficiency is also reduced.
According to another exemplary embodiment of the invention, when the mixing is performed by using the ball mill, the ball milling time is 90-96 h, too long time can cause the particle size of the WC powder to be too small, and too short time can cause the particle size of the WC powder to be too large, so that the requirement cannot be met easily.
According to another exemplary embodiment of the present invention, the pressing is performed using a servo press which enables a high precision of the pressing depth with respect to a conventional mechanical press and a high degree of repeated positioning.
According to another exemplary embodiment of the invention, the pressing is performed with a servo press, the cemented carbide mixture is pressed into a green compact with through holes, leaving a small number of technological steps at the outlet, the width of the technological steps being 0.04mm to 0.1mm, to prevent excessive damage of the punch. According to another exemplary embodiment of the present invention, the machining includes positioning the compact, and the positioning of the compact is performed by using a CCD machine vision system compact, which has high position accuracy, thereby preventing the inner hole from being eccentric to the outer circle after the machining due to the position deviation between the compact and the cutter.
According to another exemplary embodiment of the present invention, the apparatus for processing includes a boat rest on which the cells are scribed, the top surface of the boat rest having a square shape, the number of the transverse lines of the cells being 15 to 19, the number of the longitudinal lines being 15 to 19, the number of the transverse lines and the longitudinal lines of the cells being equal, each line being uniformly distributed, each cell having a hole of 1mm to 2mm, facilitating the positioning of the CCD machine vision system through the hole.
According to another exemplary embodiment of the invention, in the processing equipment, a negative pressure dust collecting device is arranged below the boat placing platform, and the inner hole of the wire-drawing die core is placed at the position of the boat hole and used for removing material particles generated in processing, sucking away the material particles, and preventing the inner hole from being stuck and blocking the hole.
Compared with the prior art, the invention has the beneficial effects that:
the compact after the hard alloy mixture is pressed is processed and then is subjected to pressure sintering, the size precision of the compact of the micropore wire-drawing die after the pressure sintering is high, the precision of the outer diameter and the height can reach the micron level, the outer diameter of a finished product is not required to be processed, the finished product can be directly inlaid, the processing procedure is simple, and the consumed time is short.
Drawings
In order to facilitate understanding for those skilled in the art, the present invention will be further described with reference to the accompanying drawings.
FIG. 1 is a schematic view of the structure of the equipment required for processing;
FIG. 2 is a green compact with a process step after pressing;
fig. 3 is a compact of the present invention after removal of the process step formed by pressing.
In the figure: 1. pressing into a blank; 2. a boat placing table; 3. a manipulator; 4. processing a cutter; 5. a machining workbench; 6. a machining control center; 7. a CCD machine vision system; 8. a negative pressure dust collecting device; 9. a dust cover; 10. a loading and unloading work center; 11. and (5) processing steps.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are further specifically described below by way of embodiments and with reference to the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as limiting the invention.
Furthermore, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in schematic form in order to simplify the drawing.
In one embodiment, a method for preparing a cemented carbide micro-porous wire-drawing die comprises the following steps:
pressing the hard alloy mixture, processing and sintering; sintering is pressure sintering, and the gas pressure during sintering is 50MPa.
In this embodiment, the preparation steps of the cemented carbide mixture are as follows:
s1, adding a grain growth inhibitor into WC powder;
s2, mixing by using a ball mill;
and S3, spray drying to obtain a hard alloy mixture.
In this example, the WC powder had a particle size of 0.2. Mu.m.
In this embodiment, the cobalt content of the WC powder is 8%, so that the wear resistance of the impact-resistant abrasive grains of the cemented carbide mixture is good.
In this example, the grain growth inhibitors are VC and Cr 3 C 2 Mixing, wherein VC accounts for 30 percent, and Cr accounts for 3 C 2 Accounting for 70 percent.
In this embodiment, the grain growth inhibitor is added to prevent grain growth or uneven growth of the sintered body during sintering.
In this embodiment, the grain growth inhibitor accounts for 1.0% of the total grain growth inhibitor volume and the sum of the two powders of WC powder, so that the effect of preventing grain growth or uneven growth of the sintered body during sintering is good.
In the embodiment, the sintering temperature is 1400 ℃, so that the density of the hard alloy mixture is better.
In the embodiment, the sintering time is 50min, so that the density of the hard alloy mixture is better.
In the embodiment, when the ball mill is used for mixing, the ball-material ratio is 6.
In this embodiment, the ball milling time is 90 hours, so that the particle size after ball milling is better.
In the embodiment, the mixture is obtained after spray drying, the Vickers hardness of the mixture is 1900-2500, the service life of the microporous wire-drawing die core is prolonged, and the requirements of users can be met.
In the embodiment, the pressing is performed by using a servo press, the hard alloy mixture is pressed into the pressed blank 1 with the through hole, a small amount of process steps 11 are left at the outlet, and the width of the process steps 11 is 0.05mm, so that the excessive damage of the punch is prevented.
In the embodiment, compared with the traditional mechanical press, the servo press can realize high-precision press-in depth, the repeated positioning is high, the position control precision is 0.005mm, and the height fluctuation of the pressed blank 1 can be controlled within 0.005mm. And can control various dwell positions and dwell time through programming, still make the single fluctuation of micropore wire drawing die pressed compact 1 can control within 0.01g, consequently can control the fluctuation of in-process single weight well to ensure the single weight size stability of pressed compact 1, with the size control of pressed compact 1 in required scope, make pressed compact 1 need not to carry out the finishing and can inlay the cover.
In the embodiment, the die body is made of the hard alloy mixture, so that the wear resistance is good, and the service life is long. After 5000 die bodies are pressed, the die bodies are worn by more than 0.01mm, and after 20000 die bodies are pressed, the wear value of the die bodies made of hard alloy is not more than 0.005mm.
In this embodiment, the size of the green compact 1 needs to be measured periodically to ensure that the diameter error of the green compact 1 is controlled within ± 0.01mm, thereby ensuring the outer diameter of the green compact 1.
In this embodiment, referring to fig. 1, during pressing, the green compact 1 is placed on the boat placing table 2, so that the manipulator 3 can grasp and position the green compact in the subsequent processing.
In this embodiment, referring to fig. 1, a mechanical arm 3 has two suction cups, one suction cup is used for sucking a green compact 1 to be processed, then the mechanical arm 3 rotates, a feeding and discharging center 10 translates to a processing table 5, the mechanical arm 3 places the green compact 1 to be processed on the processing table 5, a CCD machine vision system 7 is used for photographing and positioning the green compact, the accurate position of the green compact is fed back to a processing control center 6, and the processing control center 6 processes the green compact 1 according to the fed-back position information. After the machining is completed, the other suction cup of the robot arm 3 again places the green compact 1 back in place.
In this embodiment, the grid is scribed on the boat holding table 2, the top surface of the boat holding table 2 is 300mm, the number of the transverse lines of the grid is 17, the number of the longitudinal lines is 17, each line is uniformly distributed, the green compacts 1 are placed according to the drawn grid, each grid is provided with 2mm holes, and the manipulator 3 is positioned through the holes.
In this embodiment, the negative pressure dust collecting device 8 is arranged below the boat placing table 2, and the inner hole of the wire-drawing die core is placed at the boat hole position, so as to remove material particles generated during machining, suck the material particles away, and prevent the inner hole from being stuck and blocking the hole.
In this embodiment, during machining, the green compact 1 is placed on the boat placing table 2, the manipulator 3 picks up the green compact according to a set program, the green compact is placed on the machining table 5, and after photographing and positioning are performed by the CCD machine vision system 7, the machining tool 4 performs machining according to the positioning.
In this embodiment, after the CCD machine vision system 7 photographs and positions the green compact 1, the precise position of the green compact 1 is fed back to the machining control center 6, and the machining control center 6 adjusts the coordinates of the X axis and the Y axis of the machining tool 4 according to the obtained position information, and then performs machining.
In this embodiment, the dust cover 9 plays a role of preventing the material particles from splashing during the processing.
In this embodiment, the manipulator 3 is further provided with a loading and unloading work center 10 for controlling loading and unloading.
In this embodiment, manipulator 3 adopts the sucking disc to get pressed compact 1, and the sucking disc is the mode that the negative pressure was absorb, prevents because the pressed compact 1 that snatchs and cause from falling the corner.
In this embodiment, the loading and unloading work center 10 can translate in the directions of the X axis, the Y axis, and the Z axis.
In this embodiment, adopt CCD machine vision system 7 to shoot the location to pressed compact 1, within its position precision is steerable 0.001mm to prevented because the offset between pressed compact 1 and the cutter, and caused the processing back hole and the different "concentricity" of excircle, the concentricity can be controlled within 0.002 mm.
In this embodiment, after the green compact 1 is processed, the robot 3 takes out the green compact 1 from the processing table 5 according to the programmed program and places it back on the boat table 2, and only one boat table 2 is required for this operation.
In this embodiment, the apertures of different sizes can be obtained by adjusting the vertical position of the cutter 4.
In the embodiment, in the machining process of the hard alloy micropore wire-drawing die core, an operator only needs to replace the material plate regularly and well perform process quality control.
In this embodiment, in the process of machining the hard alloy micropore wire-drawing die core, because the aperture is small, the diameter of a corresponding Polycrystalline diamond (PCD) cutter is also small, so that the strength of the cutter is low, the cutter is easy to break in the machining process, and the cutter is easy to damage when the machining amount is larger. According to the machining method, the service life of the used PCD cutter is longer than that of the machining blind hole green compact 1 because the process step 11 only needs to be machined is smaller.
The method provided by the invention is used for preparing the hard alloy micropore wire-drawing die, and the equipment adopted by the method is combined, so that a process table formed by pressing can be effectively removed, the concentricity of the outer circle and the inner hole can be controlled within 0.002mm, micropore wire-drawing dies with different apertures can be produced, a machining cutter does not need to be replaced, and the required aperture can be obtained by controlling machining parameters.
The process steps 11 at the outlet angle of the inner hole are removed by adopting processing equipment, the process steps 11 formed in pressing can be removed efficiently in batches, the subsequent grinding time of the inner hole is greatly reduced, and the grinding efficiency of the inner hole is improved.
Referring to fig. 2 and 3, the process step 11 in fig. 2 is more obvious, the process step 11 in fig. 3 is not obvious, and the effect of removing the process step 11 is better.
This processing equipment adopts CCD image location technique, has ensured the precision of adding the repeated location of pressed compact 1 man-hour, makes the concentricity control of excircle and hole within 0.002mm, has guaranteed the axiality between hole and the excircle, prevents that it from appearing "off-centre" phenomenon after the hole grinds including.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The preparation method of the hard alloy micropore wire-drawing die is characterized by comprising the following steps:
pressing the hard alloy mixture into a pressed compact, and processing and sintering the pressed compact;
the sintering is pressure sintering, and the gas pressure during sintering is 40-60 MPa.
2. The method according to claim 1, wherein the sintering temperature is 1370-1450 ℃.
3. The method according to claim 1, wherein the sintering time is 40-60 min.
4. The method according to claim 1, wherein the step of preparing the cemented carbide micro-porous wire-drawing die comprises the steps of:
and performing ball milling and mixing on the WC powder, the cobalt powder and the grain growth inhibitor, and performing spray drying to obtain a hard alloy mixture.
5. The method of claim 4, wherein the grain growth inhibitor comprises VC and Cr 3 C 2 Wherein VC accounts for 25 to 35 percent, and Cr 3 C 2 65 to 75 percent.
6. The method for preparing a hard alloy microporous wire-drawing die according to claim 4, wherein the cobalt powder content of the mixture is 3-12%.
7. The method for preparing a hard alloy microporous wire-drawing die according to claim 4, wherein the grain growth inhibitor accounts for 0.2-1.0% of the total amount of the two powders of the grain growth inhibitor.
8. The method for preparing a hard alloy microporous wire-drawing die according to claim 1, wherein the pressing is performed by a servo press, the hard alloy mixture is pressed into a green compact with a through hole, a small number of process steps are left at an outlet, and the width of the process steps is 0.04 mm-0.1 mm.
9. A method of making a cemented carbide micro-porous die according to claim 1, wherein the machining comprises positioning the compact using a CCD machine vision system.
10. A method for preparing a cemented carbide micro-hole wire-drawing die as claimed in claim 9, wherein the processing equipment comprises a boat holding table on which the wire grid is scribed, the top surface of the boat holding table is square, the transverse lines of the wire grid are 15 to 19, the longitudinal lines are 15 to 19, the number of the transverse lines and the longitudinal lines of the wire grid is equal, each line is uniformly distributed, and each grid has 1mm to 2mm holes.
CN202211697835.8A 2022-12-28 2022-12-28 Preparation method of hard alloy micropore wire-drawing die Pending CN115846664A (en)

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