Jangka hayat acuan
- 2024-10-29
Jangka hayat acuan merujuk kepada bilangan bahagian yang boleh dibentuk sambil memastikan kualiti bahagian tersebut. Ia termasuk mengasah berulang dan menggantikan bahagian yang terdedah sehingga bahagian utama acuan diganti, menghasilkan sejumlah bahagian yang layak terbentuk.
5 Penyelenggaraan dan penyelenggaraan
Kegagalan acuan terbahagi kepada kegagalan abnormal dan kegagalan biasa. Kegagalan tidak normal (kegagalan awal) merujuk kepada ketidakupayaan acuan untuk digunakan sebelum ia mencapai jangka hayat yang diiktiraf pada peringkat industri tertentu. Bentuk awal kegagalan termasuk ubah bentuk plastik, patah tulang, dan kehausan setempat yang teruk. Kegagalan biasa merujuk kepada ketidakupayaan acuan untuk meneruskan perkhidmatan akibat ubah bentuk plastik yang perlahan, haus seragam, atau patah keletihan selepas pengeluaran dan penggunaan berskala besar.
Bilangan produk layak yang dihasilkan sebelum kegagalan biasa acuan dipanggil hayat biasa acuan, disingkatkan sebagai hayat acuan. Bilangan produk berkelayakan yang dihasilkan sebelum pembaikan pertama acuan dipanggil hayat pertama; Bilangan produk layak yang dihasilkan daripada satu pembaikan acuan kepada pembaikan seterusnya dipanggil hayat pembaikan acuan. Jangka hayat acuan ialah jumlah jangka hayat awalnya dan jangka hayat setiap pembaikan berikutnya.
Jangka hayat acuan adalah berkaitan dengan bentuk dan strukturnya, dan ia merujuk kepada sifat bahan, reka bentuk, dan tahap pembuatan acuan dalam tempoh masa tertentu. Refleksi komprehensif tahap rawatan haba, penggunaan dan penyelenggaraan acuan. Jangka hayat acuan mencerminkan sedikit sebanyak tahap industri pembuatan metalurgi dan mekanikal di rantau atau negara.
Terdapat banyak jenis acuan dengan perbezaan ketara dalam keadaan kerja dan bahagian yang rosak, tetapi mod kegagalan boleh diringkaskan secara kasar kepada tiga jenis: haus, patah dan ubah bentuk plastik.
(1) Kegagalan haus dan lusuh
Apabila acuan dalam perkhidmatan, ia bersentuhan dengan bilet yang terbentuk dan menghasilkan gerakan relatif. Fenomena kehilangan bahan secara beransur-ansur dari permukaan sentuhan akibat pergerakan relatif permukaan dipanggil haus.
(2) Kegagalan patah tulang
Apabila acuan mempunyai keretakan besar atau berpisah kepada dua atau beberapa bahagian dan kehilangan keupayaan servisnya, ia menjadi kegagalan patah. Patah boleh dibahagikan kepada patah plastik dan patah rapuh. Bahan acuan kebanyakannya adalah keluli berkekuatan sederhana hingga tinggi, dan bentuk patah kebanyakannya adalah patah rapuh. Fraktur rapuh boleh dibahagikan kepada patah satu kali dan patah keletihan.
(3) Kegagalan ubah bentuk plastik
Acuan plastik mengalami tekanan yang ketara dan tidak sekata semasa perkhidmatan. Apabila tegasan di bahagian tertentu acuan melebihi had hasil bahan acuan pada suhu tersebut, ubah bentuk plastik akan berlaku melalui gelinciran kekisi, berkembar, gelinciran sempadan bijian, dsb., mengubah bentuk atau saiz geometri, dan tidak boleh dibaiki. sebelum perkhidmatan, yang dipanggil kegagalan ubah bentuk plastik. Mod kegagalan ubah bentuk plastik termasuk menjengkelkan, membongkok, pengembangan rongga, runtuh, dll.
Ubah bentuk plastik acuan ialah proses menghasilkan bahan logam yang digunakan dalam acuan. Sama ada ubah bentuk plastik berlaku terutamanya ditentukan oleh beban mekanikal dan kekuatan suhu bilik acuan. Kejadian ubah bentuk plastik dalam acuan yang berkhidmat pada suhu tinggi terutamanya bergantung pada suhu kerja acuan dan kekuatan suhu tinggi bahan acuan.
(1) Pengaruh struktur acuan
Struktur acuan mempunyai kesan yang ketara ke atas keadaan tegasan acuan. Struktur acuan yang munasabah boleh memastikan acuan ditekankan secara seragam semasa operasi, kurang terdedah kepada pemuatan sipi, dan kurang kepekatan tegasan. Terdapat banyak jenis acuan, dengan perbezaan yang ketara dalam bentuk dan persekitaran kerja,
(2) Pengaruh keadaan kerja acuan
1) Material and temperature of formed parts
① The materials used for forming parts include metal and non-metal. Generally speaking, non-metallic materials have low strength, require less forming force, have less stress on the mold, and have a longer mold life. Therefore, the lifespan of metal forming molds is lower than that of non-metal forming molds.
② When forming high-temperature workpieces, the mold heats up due to the heat it receives. As the temperature increases, the strength of the mold decreases, making it prone to plastic deformation. At the same time, there is a significant temperature difference between the surface of the mold in contact with the workpiece and the non-contact surface, which causes temperature stress in the mold.
2) Equipment characteristics
① The precision and stiffness of the equipment are provided by the force of the mold forming the workpiece. During the forming process, the equipment will undergo elastic deformation due to the force applied.
② The force exerted by the speed equipment on the mold and workpiece gradually increases over a period of time, and the equipment speed affects the force application process. The higher the equipment speed, the greater the impact force on the mold per unit time (high impact); The shorter the time, the less time it takes for the impact energy to be transmitted and released, making it easier to concentrate locally, resulting in local stresses exceeding the yield stress or fracture strength of the mold material. Therefore, the higher the equipment speed, the more prone the mold is to fracture or plastic deformation failure.
3) Lubrication
Lubricating the relative motion surface between the mold and the billet can reduce direct contact between the mold and billet, decrease wear, and reduce forming force. At the same time, lubricants can also hinder heat transfer from the billet to the mold to a certain extent, reduce mold temperature, and be beneficial for improving mold life.
(3) The influence of mold material properties
The performance of mold materials has a significant impact on the lifespan of molds, including strength, impact toughness, wear resistance, corrosion resistance, hardness, thermal stability, and heat fatigue resistance.
(4) The impact of mold manufacturing process
1) During module forging, the temperature difference between the inside and outside caused by module heating and cooling will generate thermal stress; Improper selection of technical parameters during processes such as upsetting, punching, and expanding holes can easily lead to cracking of the forging blank. In addition, when the forging ratio exceeds a certain value, the transverse mechanical properties sharply decrease due to the formation of fibrous tissue, leading to anisotropy.
2) In the electrical machining of molds, varying degrees of deterioration layers may occur. In addition, due to local sudden heating and cooling, residual stress and cracking are easily formed.
3) Heat treatment of molds
Mold heat treatment is arranged after module forging and rough machining, and is almost the final process of mold processing. The selection of mold materials and the determination of heat treatment processes have a significant impact on the performance of molds.
(1) Purpose: To maintain optimal performance and prolong the service life of the equipment, ensuring normal production.
(2) Scope of application: Suitable for the repair and maintenance of molds.
(3) Regular inspection and maintenance: Regular maintenance and inspection should be carried out by mold repair and upper and lower mold personnel.
(4) The electrolytic ultrasonic cleaning method has better cleaning effect on the processed molds. While cleaning, it also plays a role in rust prevention
1. Daily routine inspection and maintenance:
Is the mold in operation in normal condition
a. Is there low-voltage locking protection; b. Whether the active parts such as guide posts, top rods, and rows are worn and lubricated properly. It is required to refuel at least once every 12 hours, and for special structures, the refueling frequency should be increased. c. Are the screws and locking clips of the fixed template of the mold loose;
1.2 Normal production conditions: Check whether the defects of the product are related to the mold;
1.3 When dismounting, a comprehensive inspection of the mold should be conducted and rust prevention treatment should be carried out: wipe dry the moisture in the mold cavity, core, ejection mechanism, and row position, and spray mold rust inhibitor or apply butter.
1.4 The mold after being removed from the machine should be placed in the designated location and recorded:
a. Mold condition: intact or in need of repair. b. The anti rust treatment method during mold making.
2. Quarterly routine inspections:
Mainly for cleaning and maintaining molds that have not been used for more than two months.
2.1 Open the mold and check the internal rust prevention effect. If there are any abnormal situations, rust prevention treatment must be carried out again. Molds that are not used for a long time should be coated with butter.
2.2 Return to its original position and make records.
Mold is the basic process equipment for mechanical industry production and an indispensable tool in the production of industrial products. The performance of molds made of mold steel requires strict production process supervision, and the raw materials for mold production must also be strictly controlled to prevent early failure, heat treatment cracking, and other defects caused by material problems.
The control of raw materials for molds is carried out from the following aspects:
1. Macro inspection
The chemical composition is decisive in ensuring the performance of steel, but qualified composition cannot fully explain the performance of steel. Due to the unevenness of the internal structure and composition of steel, macroscopic inspection largely supplements this deficiency. Macroscopic testing can observe the crystallization of steel, the failure of steel continuity, and the non-uniformity of certain components. Eight common macroscopic defects: segregation, porosity, inclusions, shrinkage, bubbles, white spots, cracks, and folds.
2. Evaluation of annealed tissue
The purpose of annealing is to reduce the hardness of steel, facilitate machining, and also prepare the structure for subsequent heat treatment.
3. Non-uniformity of carbides
Cr12 type martensitic steel contains a large amount of eutectic carbides in its microstructure, and the unevenness of carbides has a very important impact on its performance. Therefore, strict control must be exercised over the distribution of carbides.
In summary, due to the complexity of the production objects in mold factories and workshops, and the fact that they are mostly single pieces or small batches, it brings certain difficulties to the formulation and management of mold production quotas. In addition, the production methods, equipment, and technical qualities of each factory and workshop are not the same. Therefore, when formulating quotas, it is necessary to find appropriate methods to develop advanced and reasonable working hour quotas based on the actual situation of the factory and workshop, in order to improve labor productivity.
-
TAG：
Hantar Pertanyaan Anda Sekarang