A high-precision oleic acid adding method and device

Abstract

This invention provides a high-precision oleic acid addition method and apparatus. Liquid oleic acid is placed in an environment below its melting point, causing it to completely solidify into a solid oleic acid block. While maintaining a low temperature below the melting point of oleic acid, the solid oleic acid block is physically crushed into particles, which are then sieved. The required oleic acid mass is calculated based on the required oleic acid volume and the density of oleic acid at the current ambient temperature. The sieved solid oleic acid particles are then weighed according to the required mass. The weighed solid oleic acid particles are transferred to a ball mill jar and ball-milled together with the basic raw materials required in the cemented carbide production process. The solid oleic acid particles naturally melt under the frictional heat generated by the ball mill and the ambient temperature, thus completing the oleic acid addition.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy and cemented carbide manufacturing technology, specifically relating to a high-precision oleic acid addition method and apparatus. Background Technology

[0002] In the production of cemented carbide, the ball milling and mixing of basic raw materials such as tungsten carbide (WC) powder and cobalt (Co) powder with trace amounts of forming agents is a core process that determines the quality of the final alloy product. Oleic acid, as one of the most commonly used forming agents, is typically added at a level of only 1-2 ml per kilogram of mixture. This amount is extremely small, but it has a decisive impact on the uniformity of the mixture, its pressing performance, and the carbon content, phase composition, and mechanical properties of the alloy after sintering.

[0003] Oleic acid not only acts as a lubricant during forming, but also, as an organic carbon source, directly participates in the carbon balance during sintering. In cemented carbide grades near the carbon balance critical point, even slight fluctuations in the amount of oleic acid added will lead to a shift in the total carbon content of the alloy, resulting in drastic changes in cobalt magnetic properties and phase composition. Taking the WC-10Co-0.6Cr3C2 cemented carbide system as an example, systematic experiments show that when the actual effective amount of oleic acid added is significantly lower than the process set value (e.g., 1.5 ml), the alloy is in a carbon-deficient state, and a brittle η phase (Co3W3C) will be generated after sintering, leading to an abnormal decrease in the cobalt magnetic property. However, when the oleic acid is added accurately and sufficiently, the alloy carbon content is normal, and the cobalt magnetic property remains stable within the ideal range of 8.0%-8.5%. Even a shift of only 0.5% in cobalt magnetic properties indicates a significant change in the amount of tungsten dissolved in the cobalt binder phase, which will directly cause unacceptable batch-to-batch fluctuations in product hardness, bending strength, and fracture toughness, severely damaging the performance consistency of cemented carbide tools.

[0004] Currently, the industry commonly uses glass graduated cylinders for manual measurement and addition of liquid oleic acid. This method has the following inherent drawbacks: 1. Severe adhesion loss and uncontrollable error: Oleic acid has a high viscosity and will adhere to the inner wall of the container in large quantities during pouring. For a single addition of 1.5ml, the actual loss due to adhesion can reach 0.1-0.2ml, and the amount of adhesion is random each time, thus introducing an uncontrollable addition error of up to 3%-10%.

[0005] 2. Volumetric measurement is greatly affected by ambient temperature: the density of oleic acid decreases significantly with increasing temperature. Seasonal or diurnal temperature variations can cause the actual mass corresponding to the same volume of oleic acid to drift, disrupting the stability of process conditions between different batches.

[0006] 3. Low reading accuracy and cumbersome operation: It relies on manual visual reading of the concave liquid surface, which is subject to subjective parallax, and the high viscosity of the liquid can easily lead to irregular liquid surface; this manual method is difficult to integrate with the automated batching system. Summary of the Invention

[0007] Based on this, the present invention provides a high-precision oleic acid addition method and apparatus, which aims to solve the problems of large adhesion loss, strong environmental temperature interference, low addition accuracy, and ultimately uncontrolled carbon content, cobalt magnetic deviation and poor mechanical property consistency of the existing liquid oleic acid addition method.

[0008] A first aspect of this invention provides a high-precision oleic acid addition method, comprising the following steps: Liquid oleic acid is placed in an environment below its melting point, causing it to completely solidify into a solid oleic acid block. Under conditions of maintaining a low temperature below the melting point of oleic acid, the solid oleic acid block is physically crushed to form particles, and the crushed particles are then sieved. Calculate the required oleic acid mass based on the required oleic acid volume and the oleic acid density at the current ambient temperature, and weigh the sieved solid oleic acid particles according to the required oleic acid mass. The weighed solid oleic acid particles are transferred into a ball mill jar and ball-milled together with the basic raw materials required in the production of cemented carbide. During the ball milling process, the solid oleic acid particles naturally melt under the frictional heat and ambient temperature, thus completing the addition of oleic acid.

[0009] Furthermore, in the step of placing liquid oleic acid in an environment below its melting point to completely solidify it into a solid oleic acid block, the liquid oleic acid is placed in an environment of 0°C to 10°C.

[0010] Furthermore, in the step of physically crushing the solid oleic acid block into particles under conditions of maintaining a low temperature below the melting point of oleic acid, the solid oleic acid block is physically crushed under low temperature conditions of 0℃~10℃.

[0011] Furthermore, in the step of sieving the crushed particles, the particle size of the sieved particles is 0.35mm~0.55mm.

[0012] Furthermore, in the step of weighing the sieved solid oleic acid particles according to the required oleic acid mass, the accuracy of the balance used for weighing shall not be less than 0.01g.

[0013] Furthermore, the ambient temperature is 24℃~26℃.

[0014] A second aspect of the present invention provides a high-precision oleic acid addition device for implementing the high-precision oleic acid addition method described in the first aspect of the present invention, the device comprising: A low-temperature solidification module is used to provide a low-temperature environment to solidify liquid oleic acid; The low-temperature crushing and screening module is used to crush and screen the solid oleic acid block obtained by the cooling and solidification module. It has a built-in crushing mechanism and a vibrating screen. The built-in crushing mechanism integrates an auxiliary refrigeration element to maintain a low-temperature environment. The heat-insulating storage and vibrating feeding module is used to temporarily store qualified particles obtained from the low-temperature crushing and screening module, and to feed them to the weighing module through a vibrating feeder. The weighing module, which includes an electronic balance and a weighing container, controls the start and stop of feeding through closed-loop feedback to ensure that the target quality is achieved. An integrated control module is used to coordinate the temperature and operation of each module, and it has an ambient temperature compensation function, enabling one-click automated operation.

[0015] This invention provides a high-precision oleic acid addition method and apparatus. Liquid oleic acid is placed in an environment below its melting point, causing it to completely solidify into a solid oleic acid block. While maintaining a low temperature below the melting point of oleic acid, the solid oleic acid block is physically crushed into particles, which are then sieved. The required oleic acid mass is calculated based on the required oleic acid volume and the density of oleic acid at the current ambient temperature. The sieved solid oleic acid particles are then weighed according to the required mass. The weighed solid oleic acid particles are transferred to a ball mill jar and ball-milled together with the basic raw materials required in the cemented carbide production process. The solid oleic acid particles naturally melt under the frictional heat generated by ball milling and the ambient temperature, thus completing the oleic acid addition. Specifically, by utilizing the physical property of oleic acid solidifying at low temperatures, high-viscosity liquid oleic acid is transformed into free-flowing, non-sticky solid particles, thereby changing the measurement method from vague "volume measurement" to precise "mass weighing," fundamentally eliminating random error sources in carbon content control. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the implementation of a high-precision oleic acid addition method proposed in an embodiment of the present invention.

[0017] The following detailed embodiments will be further described in conjunction with the above-mentioned accompanying drawings. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0019] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein 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. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Please see Figure 1 The following is a flowchart illustrating the implementation of a high-precision oleic acid addition method proposed in an embodiment of the present invention, wherein the preparation method includes the following steps: Step S01: Place the liquid oleic acid in an environment below its melting point to allow it to completely solidify into a solid oleic acid block.

[0022] Specifically, liquid oleic acid has a melting point of 13℃~14℃. When liquid oleic acid is placed in an environment of 0℃~10℃, it can be completely solidified into solid oleic acid blocks.

[0023] Step S02: Under conditions of maintaining a low temperature below the melting point of oleic acid, the solid oleic acid block is physically crushed to form particles, and the crushed particles are then sieved.

[0024] Specifically, the solid oleic acid block is physically crushed at a low temperature of 0℃ to 10℃, and the particle size of the obtained particles by sieving is 0.35mm to 0.55mm. It can be understood that physical crushing at low temperature is intended to prevent the particles from melting locally and re-adhering due to frictional heat.

[0025] In this embodiment of the invention, the particle size is preferably 0.45 mm. It should be noted that if the particle size is greater than 0.55 mm, the specific surface area is too small, and it takes a long time to completely melt during ball milling, which affects the uniform distribution of the molding agent in the initial stage of mixing. Particles smaller than 0.35mm have an excessively large specific surface area, which easily absorbs heat, softens, clumps, and adheres to equipment during weighing and transfer, and also generates dust. With a particle size between 0.35mm and 0.55mm, it balances good flowability and anti-adhesion properties, and can quickly melt and disperse in the early stage of ball milling to achieve the process objectives.

[0026] Step S03: Calculate the required oleic acid mass based on the required oleic acid volume and the oleic acid density at the current ambient temperature, and weigh the sieved solid oleic acid particles according to the required oleic acid mass.

[0027] The required oleic acid mass is the product of the oleic acid volume and the oleic acid density at the current ambient temperature. An electronic balance with an accuracy of not less than 0.01g is used to accurately weigh the preset mass of solid oleic acid particles.

[0028] Step S04: The weighed solid oleic acid particles are transferred into a ball mill jar and ball-milled together with the basic raw materials required in the production process of cemented carbide. The solid oleic acid particles melt naturally under the frictional heat generated by the ball mill and the ambient temperature to complete the addition of oleic acid.

[0029] In this embodiment of the invention, the basic raw materials required for the production of cemented carbide include WC powder, Co powder, etc., and the ambient temperature is controlled at 24℃~26℃.

[0030] To achieve the above method, embodiments of the present invention also provide a high-precision oleic acid addition device, comprising: A low-temperature solidification module is used to provide a low-temperature environment to solidify liquid oleic acid; The low-temperature crushing and screening module is used to crush and screen the solid oleic acid block obtained by the cooling and solidification module. It has a built-in crushing mechanism and a vibrating screen. The built-in crushing mechanism integrates an auxiliary cooling element to maintain a low-temperature environment. The screen aperture is configured to obtain particles with an average particle size of 0.35mm to 0.55mm. The heat-insulating storage and vibrating feeding module is used to temporarily store qualified particles obtained from the low-temperature crushing and screening module, and to feed them to the weighing module through a vibrating feeder. The weighing module, which includes an electronic balance and a weighing container, controls the start and stop of feeding through closed-loop feedback to ensure that the target quality is achieved. An integrated control module is used to coordinate the temperature and operation of each module, and it has an ambient temperature compensation function, enabling one-click automated operation.

[0031] To facilitate understanding of the present invention, several embodiments are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0032] Example 1 In Embodiment 1 of this invention, a high-precision oleic acid addition method is provided. Specifically, the operating conditions are: workshop temperature 25℃, and the process requirement is to add 1.5 ml of oleic acid per kilogram of WC-10Co-0.6Cr3C2 mixture. At this temperature, the density of oleic acid is approximately 0.895 g / cm³. 3Theoretically, the added mass should be 1.343g.

[0033] The operation steps are as follows: 1. Cooling and solidification: Liquid oleic acid is placed in the 5°C cooling chamber of the device and left to stand for 24 hours to solidify into a solid.

[0034] 2. Low-temperature crushing and screening: Start the device, and the temperature of the low-temperature module stabilizes at 5℃. Put in the solid oleic acid block, and after being crushed by the rotating blades, the particles with an average particle size of 0.45mm are collected through a combination of 40-mesh and 60-mesh screens.

[0035] 3. Precise Weighing: Input the target mass "1.343g" into the control system. The vibrating feeder adds material to the weighing hopper, and the balance (accuracy 0.001g) provides real-time feedback. It stops instantly after reaching the target value. Repeat 10 times.

[0036] 4. Addition and sintering: Pour all the particles into a ball mill jar, press them, and sinter them at 1420℃.

[0037] result: Addition accuracy: The results of 10 weighings were all between 1.342g and 1.344g, with a range of only 0.002g, which basically achieved the addition of the theoretical mass.

[0038] Product performance: The cobalt magnetic values ​​of the 10 samples were concentrated and stable in the ideal range of 8.2%-8.4% (with a range of only 0.2%), and the microstructure showed no η phase. The Vickers hardness HV30 range decreased to 9, and the fracture toughness KIC range was only 0.3 MPa·m-1 / 2.

[0039] Conclusion: This invention ensures the absolutely precise addition of trace amounts of oleic acid, making the carbon content of the alloy stable and under control, and fundamentally improving the consistency of the mechanical properties of the product.

[0040] Example 2 In Embodiment 2 of this invention, a high-precision oleic acid addition method is also provided. The difference from Embodiment 1 is that when the workshop temperature rises from 25°C to 35°C, the system automatically increases the cooling power and shortens the feeding residence time to ensure that the temperature throughout the process is below the melting point of oleic acid. After repeated testing under high-temperature conditions, the particle morphology and weighing accuracy were not affected, and the cobalt magnetism remained stable between 8.0% and 8.5%.

[0041] Comparative Example 1 Comparative Example 1 of this invention provides a conventional method for adding oleic acid, with the same operating conditions as in Example 1. The procedure is as follows: 1.5 ml of liquid oleic acid is measured using a glass graduated cylinder and poured into a pre-weighed ball mill jar. The mass difference before and after weighing is measured, and this process is repeated 10 times. The mixture is then pressed and vacuum sintered at 1420℃ to form an alloy sample.

[0042] result: Addition accuracy: The actual added masses in 10 tests were 1.15g, 1.31g, 1.08g, 1.27g, 1.17g, 1.38g, 1.22g, 1.06g, 1.29g, and 1.18g, respectively. The average was 1.21g, with a range of 0.32g. A significant amount of oleic acid remained in the graduated cylinder in an uncontrollable manner.

[0043] Product performance: The cobalt magnetic properties of the 10 samples fluctuated wildly between 7.2% and 8.8%, with a range of 1.6%. Several samples had cobalt magnetic properties below 7.5%, and the microstructure showed obvious decarburized η phase. The Vickers hardness HV30 range reached 62, and the fracture toughness KIC range was 1.8 MPa·m⁻¹ / ².

[0044] Conclusion: The uncontrollable addition error of traditional methods directly leads to runaway carbon content and severe dispersion of mechanical properties.

[0045] In summary, the high-precision oleic acid addition method and apparatus proposed in this invention involves placing liquid oleic acid in an environment below its melting point, causing it to completely solidify into a solid oleic acid block. While maintaining a low temperature below the melting point of oleic acid, the solid oleic acid block is physically crushed into particles, which are then sieved. The required oleic acid mass is calculated based on the required oleic acid volume and the density of oleic acid at the current ambient temperature. The sieved solid oleic acid particles are then weighed according to the required mass. The weighed solid oleic acid particles are transferred to a ball mill jar and ball-milled together with the basic raw materials required in the cemented carbide production process. The solid oleic acid particles naturally melt under the frictional heat generated by the ball mill and the ambient temperature, thus completing the oleic acid addition. Specifically, by utilizing the physical property of oleic acid solidifying at low temperatures, the high-viscosity liquid oleic acid is transformed into free-flowing, non-sticky solid particles, thereby changing the measurement method from vague "volume measurement" to precise "mass weighing," fundamentally eliminating random error sources in carbon content control.

[0046] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A high-precision oleic acid addition method, characterized in that, Includes the following steps: Liquid oleic acid is placed in an environment below its melting point, causing it to completely solidify into a solid oleic acid block. Under conditions of maintaining a low temperature below the melting point of oleic acid, the solid oleic acid block is physically crushed to form particles, and the crushed particles are then sieved. Calculate the required oleic acid mass based on the required oleic acid volume and the oleic acid density at the current ambient temperature, and weigh the sieved solid oleic acid particles according to the required oleic acid mass. The weighed solid oleic acid particles are transferred into a ball mill jar and ball-milled together with the basic raw materials required in the production of cemented carbide. During the ball milling process, the solid oleic acid particles naturally melt under the frictional heat and ambient temperature, thus completing the addition of oleic acid.

2. The high-precision oleic acid addition method according to claim 1, characterized in that, In the step of placing liquid oleic acid in an environment below its melting point to completely solidify it into a solid oleic acid block, the liquid oleic acid is placed in an environment of 0℃~10℃.

3. The high-precision oleic acid addition method according to claim 1, characterized in that, In the step of physically crushing the solid oleic acid block into particles under conditions of maintaining a low temperature below the melting point of oleic acid, the solid oleic acid block is physically crushed under low temperature conditions of 0℃~10℃.

4. The high-precision oleic acid addition method according to claim 1, characterized in that, In the step of screening the crushed particles, the particle size of the particles obtained by screening is 0.35mm~0.55mm.

5. The high-precision oleic acid addition method according to claim 1, characterized in that, In the step of weighing the sieved solid oleic acid particles according to the required oleic acid mass, the accuracy of the balance used for weighing shall not be less than 0.01g.

6. The high-precision oleic acid addition method according to claim 1, characterized in that, The ambient temperature is 24℃~26℃.

7. A high-precision oleic acid addition device, characterized in that, The apparatus for implementing the high-precision oleic acid addition method according to any one of claims 1 to 6 comprises: A low-temperature solidification module is used to provide a low-temperature environment to solidify liquid oleic acid; The low-temperature crushing and screening module is used to crush and screen the solid oleic acid block obtained by the cooling and solidification module. It has a built-in crushing mechanism and a vibrating screen. The built-in crushing mechanism integrates an auxiliary refrigeration element to maintain a low-temperature environment. The heat-insulating storage and vibrating feeding module is used to temporarily store qualified particles obtained from the low-temperature crushing and screening module, and to feed them to the weighing module through a vibrating feeder. The weighing module, which includes an electronic balance and a weighing container, controls the start and stop of feeding through closed-loop feedback to ensure that the target quality is achieved. An integrated control module is used to coordinate the temperature and operation of each module, and it has an ambient temperature compensation function, enabling one-click automated operation.

Images