CN-121989495-A - Method for improving weight, height and density uniformity of PTS compression molding part

Abstract

The invention belongs to the field of material molding, in particular to a method for improving weight, height and density homogeneity of PTS compression molding parts, which comprises the following steps: the method comprises the steps of filling powder into a mold cavity through a vibration auxiliary quantitative feeding device at the temperature T, and heating and preserving heat of the feed bin to ensure that the powder has good fluidity. A mechanical arch breaker is arranged to solve the problem of blanking interruption. And a vibration feeder device is adopted to ensure the consistent quality of materials filled into the die cavity each time. The traditional single-pressure pressing is abandoned, and a multi-stage (pre-pressing, main pressing and coining) pressure curve is adopted. The bidirectional pressing technology is introduced, so that the pressure loss caused by unidirectional friction is effectively counteracted, and the powder body is stressed more uniformly in the height direction. The key is that the pressure and displacement are monitored in real time to form closed-loop control, so that the influence caused by material fluctuation can be automatically compensated.

Inventors

• YANG LIN
• Lv Zunhua
• ZHANG JUNHUA
• WEN XIANJUN
• QING HONG
• LI BINGKUN
• Su Mulin

Assignees

• 四川嘉宜新材料科技有限公司

Dates

Publication Date

20260508

Application Date

20260331

Claims (7)

1. 1. A method for improving the weight, height and density uniformity of a PTS compression molded article, comprising the steps of: S1, filling, namely placing powder into a feed bin with a temperature control function and a mechanical arch breaker, and filling the powder into a die cavity through a vibration auxiliary quantitative feeding device at the temperature T; S2, intelligent mould pressing, namely applying pressure to the upper punch and the lower punch of the mould, and executing bidirectional synchronous pressing, wherein in the pressing process, the pressure P and the upper punch displacement H are monitored in real time, real-time data of the P and the H are compared with a P-H target curve preset on the basis of a powder compression constitutive model, and the pressure application is dynamically regulated through a controller, so that an actual P-H curve tracks the target curve; and S3, maintaining the pressure and demolding, namely maintaining the pressure for a period of time after the target pressing end point is reached, and then releasing the pressure and demolding.
2. 2. The method for improving weight, height and density uniformity of PTS compression molded parts according to claim 1, wherein said temperature T is controlled at 40-50 ℃.
3. 3. The method of improving the weight, height and density uniformity of PTS compression molded parts according to claim 1, wherein the vibration frequency of said vibration auxiliary quantitative feeding device in step S1 is 35-50Hz and the amplitude is 0.1-0.5mm.
4. 4. The method for improving the weight, the height and the density uniformity of PTS compression molded parts according to claim 1, wherein the intelligent compression molding in the step S2 comprises the following steps: S21, establishing a P-H target curve, namely obtaining the pressure-displacement relation of the specific graphite powder in the densification process through a preliminary experiment, and defining the pressure-displacement relation as the target curve; s22, bidirectional synchronous pressing, namely controlling the upper punch and the lower punch to move oppositely at the same speed, ensuring that a neutral layer is formed in the middle of the powder body, and reducing density gradient; s23, multi-stage self-adaptive control is carried out, wherein the pressing process is divided into a low-pressure pre-pressing area, a medium-pressure transition area and a high-pressure coining area.
5. 5. The method of increasing weight, height and density uniformity of PTS compression molded parts according to claim 4, wherein displacement control is the main means in said low pressure pre-compression zone to ensure air discharge.
6. 6. The method of improving weight, height and density uniformity of PTS compression molded parts according to claim 4, wherein the medium pressure transition zone and the high pressure coining zone are switched to be mainly controlled by pressure, and the pressure value and dwell time of the final stage are finely adjusted in real time according to the deviation of the actual displacement from the target displacement.
7. 7. The method of claim 4, wherein the intelligent pressing control unit comprises a servo press, a pressure sensor, a displacement sensor and a central processor for executing a P-H double closed-loop control algorithm; The pressure sensor is used for monitoring the pressure P in the pressing process in real time, the displacement sensor is used for monitoring the upper punch displacement H in real time, and the central processing unit is used for receiving real-time data of P and H, comparing the real-time data with a preset P-H target curve and dynamically adjusting a pressure application strategy.

Description

Method for improving weight, height and density uniformity of PTS compression molding part Technical Field The invention belongs to the field of material molding, and in particular relates to a method for improving weight, height and density uniformity of PTS compression molding parts. Background PTS compression molding technology is widely applied to the fields of manufacturing mechanical parts, electrical and electronic elements, ceramic products and the like, and the basic process is that loose materials are filled into a die cavity, pressurized by a punch to densify the loose materials, and then demoulded and molded; at present, the blanking mode in the PTS compression molding process mainly depends on a hopper, and naturally flows into a die cavity by means of the gravity of powder, and when facing graphite powder with poor fluidity, the blanking mode has a plurality of defects: Firstly, the blanking is difficult and bridging is frequently generated, graphite pressed powder is easy to form an arch bridge-shaped structure at the outlet of a hopper, the blanking process is interrupted or discontinuous, the blanking process can be recovered only by manual intervention, the production efficiency is reduced, and the blanking quantity is difficult to keep uniform; secondly, the fluctuation of the weight and the height of the green body is large, the actual weight of the powder filled into the die cavity each time cannot be accurately controlled due to the discontinuous and unstable blanking process, and further, the height of the formed green body is obviously different, and the size consistency of the product is affected; Moreover, the density distribution of the green body is uneven, the powder density entering the die cavity at different time intervals is greatly different due to the instability of blanking, a remarkable density gradient is formed, the density gradient can be further amplified due to uneven shrinkage in the subsequent high-temperature treatment process, defects such as deformation and cracking of a product are easily caused, meanwhile, obvious anisotropism of product performance (such as strength and resistivity) is caused, and the use requirement of a high-quality product cannot be met. Besides the problems brought by the blanking mode, other core defects exist in the existing PTS compression molding process. In the pressing process, friction force is generated between powder particles and the inner wall of a die in the unidirectional pressing process, the friction force can lead to attenuation of pressing pressure along the pressing direction, and further a density distribution state of 'up-close and down-loose' is formed, the density non-uniformity can further cause uneven shrinkage of products in the subsequent sintering process, the risks of deformation and cracking are aggravated, meanwhile, the stability of the traditional PTS compression molding process is poor, the pressure and stroke parameters of the traditional PTS compression molding process are mainly set depending on the experience of operators, a real-time monitoring and dynamic feedback adjusting mechanism for the whole pressing process is lacked, large fluctuation exists in quality of different batches of products, and quality uniformity control in the batch production process is difficult to realize. To this end, the present invention provides a method for improving the weight, height and density uniformity of PTS compression molded parts. Disclosure of Invention In order to overcome the deficiencies of the prior art, at least one technical problem presented in the background art is solved. The technical scheme adopted by the invention for solving the technical problems is that the method for improving the weight, the height and the density homogeneity of the PTS compression molding part comprises the following steps: S1, filling, namely placing powder into a feed bin with a temperature control function and a mechanical arch breaker, and filling the powder into a die cavity through a vibration auxiliary quantitative feeding device at the temperature T; S2, intelligent mould pressing, namely applying pressure to the upper punch and the lower punch of the mould, and executing bidirectional synchronous pressing, wherein in the pressing process, the pressure P and the upper punch displacement H are monitored in real time, real-time data of P and H are compared with a P-H target curve preset on the basis of a powder compression constitutive model, and the pressure application is dynamically regulated through a controller, so that an actual P-H curve tracks the target curve; and S3, maintaining the pressure and demolding, namely maintaining the pressure for a period of time after the target pressing end point is reached, and then releasing the pressure and demolding. Preferably, the temperature T in step S1 is controlled to be 40-50 ℃. Preferably, in the step S1, the vibration frequency of the vibration auxiliary quantitative