First, the design background of comprehensive safety protection device for lathe work training.
In technical colleges, mechanical students often have the following three kinds of internship teaching safety accidents during the practice operation of ordinary lathes:
1. Case 1
Many beginners do not take out the chuck key immediately after installing the workpiece in the lathe chuck because of their weak safety awareness, which violates the operation safety regulations. They go to install turning tools or do other preparatory work, forget that the chuck key is still inserted in the chuck, and then start the machine tool, causing the chuck key to fly out of the high-speed rotating chuck, which is likely to hit people near the front and back of the machine tool or the machine tool, or even break the chuck key. For example, a student in 06 electromechanical class had the above situation during the training. Fortunately, the chuck key did not hit people, but was hit on the lathe guide rail, and the chuck key was severely deformed due to fracture.
2. Case 2
When students need to cut near the chuck end according to the processing technology of parts, they often just watch the lathe tool cut the workpiece because of nervousness or inexperience, but don't notice the distance between the square tool holder and the chuck claw. At the same time, due to the high-speed rotation of the chuck, their eyes are prone to illusion that there is still a distance between the chuck claw and the tool holder, which causes the square tool holder to hit the chuck claw rotating at high speed, resulting in the collapse of the tool holder and jaw. In addition, when cutting at the proximal end, the novice is not skilled. This happens the most. Before installing safety devices on more than 30 lathes in our school, more than 96% square tool holders were injured to varying degrees.
3. Case 3
Some students can't stop when operating the reversing handle to quickly move the tool vertically, because they violate the safety operation rules or make mistakes, which causes the tool holder box to hit the three-bar bracket at the end of the lathe when reversing, resulting in the damage of the tool holder box. For example, out of curiosity, a student in the electromechanical integration class of Grade 07 violated the operating requirements of the trainer, and used the lead screw to drive the carriage, put on the high-speed gear and move the knife in the opposite direction at high speed. As a result, the pallet box hit the three-bar bracket at the end of the lathe, which caused the pallet box to be damaged and scrapped.
Over the years, the above-mentioned accidents have occurred from time to time in the practice of ordinary lathes, which has caused the trainee teachers to be nervous and have certain psychological pressure, and they are afraid of safety accidents in the practice class. According to statistics, two years before the installation of the device, more than 30 lathes in our school had more than a dozen accidents such as machine collision caused by students' unskilled operation, misoperation or violation of safety operation rules, and 9 chucks were broken and deformed when flying out. Two crates were smashed and scrapped, two were repaired by collision, and five were moderately collided; 96% of the square tool holders have different degrees of collision, collapse and injury. This has caused certain economic losses to the school, and also affected the normal and smooth development of practical teaching.
In order to ensure the safe and smooth development of practical teaching and prevent accidents, the author has carried out innovative design of safety technical transformation for practical lathes. At the beginning of 2008, through R&D design and production, the technical transformation of "multifunctional lathe training comprehensive safety protection device" was completed. After more than two years of practical verification, the effect is remarkable, and the goal of "no accidents in the practical teaching of ordinary lathes" has been realized.
At the national conference on propaganda and ideological work held in February, 2003, President Hu Jintao clearly put forward: "We should publicize and carry forward the spirit of emancipating the mind, being determined to reform, working hard and pioneering, and constantly enhance the creativity of the Chinese nation ..." We are in the era of advancing with the times and reform and opening up, shouldering the heavy responsibility of teaching reform, technological reform and management reform on the front of technical education, and more importantly, cultivating students' awareness of safe and civilized production. As a technical school practice instructor, the author analyzes and summarizes the causes of personal and equipment safety accidents caused by students' nervousness or careless operation in lathe practice, carries out technical transformation on the lathe, and designs and manufactures safety protection devices with comprehensive protection functions.
Second, the main structure and function of comprehensive safety protection device for lathe work training
The device consists of three parts: safety protection device for starting chuck key, anti-collision protection device for square tool rest and anti-collision protection device for carriage. These three sets of devices are respectively installed at the lower left of the headstock at the front of the lathe bed, below the front end of the guide rail at the rear of the lathe bed and below the rear end of the guide rail at the rear of the lathe bed (Figure 1, Figure 2 and Figure 3).
1. Main structure and function of "chuck key start safety protection device"
The "device" consists of a micro-control switch, a chuck key socket, a plastic pressing block and other components, as shown in figure 1. When the chuck key is inserted into the cylindrical socket, press the electric control switch and the machine tool can be started; When the chuck key is forgotten to be taken out of the chuck, the machine tool cannot be started. This "device" effectively prevents students from starting the lathe after leaving the chuck key on the chuck socket, and plays a role in protecting students' personal safety and machine tool equipment.
2. The main structure and function of the "square tool holder anti-collision safety protection device"
The "device" is composed of micro electronic control switch, adjustable iron, limit stop iron and buffer spring, as shown in Figure 2.
When students cut the workpiece near the chuck end or automatically feed the tool to the terminal limit position (that is, the contact point between the chuck claw and the square tool holder), there is still a distance of 3 ~ 5 mm (this distance can be adjusted freely), and the adjustable weight will trigger the micro-electric control switch, at which time the machine tool will automatically stop, thus avoiding the collision between the square tool holder and the high-speed rotating chuck and realizing the shutdown protection. However, due to the inertia force of the emergency stop, the tool rest will still move forward on the tool rest. At this time, the buffer spring and the limit stop iron of the device play a buffering role and a top stop positioning role, so that the carriage stops completely before the limit position, which plays an absolutely safe and reliable protection role. The device effectively prevents the collision accident between the square tool rest and the chuck, and plays a role in ensuring the safety of the equipment.
3. The main structure and function of the "car anti-collision protection device"
The "device" consists of a miniature electric control switch, an adjustable weight, a switch bracket and a bolt, as shown in Figure 3.
When the reversing handle is operated to carry out longitudinal reverse fast automatic feed, and the machine can't stop due to negligence or misoperation, the adjustable iron touches the micro-electric control switch, and the machine tool automatically stops after power failure, thus preventing the accident that the carriage collides with the bracket in the reverse direction and playing a reliable role in protecting the safety of the equipment.
Third, the main innovation of comprehensive safety protection device for lathe work training
The comprehensive safety protection device for lathe work practice is designed and made by analyzing and summarizing the common safety accidents that students have encountered in lathe work practice for many years. The device has the omni-directional safety protection functions of "chuck key start safety protection", "square tool rest anti-collision safety protection" and "sliding box anti-collision protection", which is safe, reliable and effective, protects students' personal and equipment safety, and realizes the goal of "zero accident" in practice class.
It is understood that this equipment has not been found as a "multifunctional comprehensive safety protection device" in the training lathes of various vocational colleges at present, and it has three functions. This project innovates and fills the gap in the invention of multifunctional safety protection equipment for lathe work practice in technical colleges. Because of its obvious function, good effect and remarkable economic and social benefits, this design won the second prize in the "First Innovative Design Competition for Teachers and Students in Guangzhou Municipal Technical Colleges" sponsored by Guangzhou Human Resources and Social Security Bureau on 20 10 and the "Ninth National Excellent Achievement Selection of Technical Colleges" organized by China Vocational Association.
Four, lathe worker comprehensive safety protection device use effect training
The practice in the past three years has proved that since the installation of "Multifunctional Comprehensive Safety Protection Device" on the general lathe in our school in 2008, there have been no teaching accidents such as chuck spoon flying out, square tool rest being hit, sliding box being hit, etc., which effectively prevented the accidents caused by students' inexperience, irregularity and violation of safety operation rules in lathe training, ensured the personal safety of students and equipment safety, and avoided the economic losses caused by the accidents. This "device" does have a comprehensive protection, safety and reliability, and remarkable effect. The device has also made a useful attempt and a good demonstration for the technical transformation of safety performance of other teaching equipment such as training machine tools in the future.
The Popularization and Application Value of verb (the abbreviation of verb)
The comprehensive safety protection device for lathe training has the characteristics of simple structure, low production cost (material cost 100 yuan/set), beautiful appearance, multiple protection functions, safety and reliability, obvious effect and great practical value. After installation, the appearance and machining performance of the machine tool are not affected, and the function and effect are ideal.
According to the survey, general teachers generally report that the practice instructor is much more relaxed after being equipped with this "device", and there is no mental tension and psychological pressure for fear of safety accidents in previous practice classes. As more than 30 ordinary lathes in our school are all equipped with this device, students have never had a safety accident of machine tool collision or personal injury in actual operation. At the same time, more than 90% of the students reported: "Even if the operation is unskilled or careless, we are not afraid of colliding with the machine, because the' device' will automatically stop for protection, and we will not have the ideological burden of being criticized for crashing the machine tool, so we can practice on the machine easily and happily." The "device" has obvious practical effect, obvious economic and social benefits, and can be popularized to the installation and use of general lathe training in vocational colleges and the safe transformation of machine tools and equipment in enterprises.
(Author: Guangzhou Public Utilities Senior Technical School, Guangdong Province)