Fundamentals of Mechanical Manufacturing Technology” is a new main technical foundation course recommended by the Steering Committee of Mechanical Engineering in 1998, which is a very strong theoretical and practical course with important engineering application value.
The course is mainly supported by the basic theory and basic knowledge of mechanical process and cutting principle, and the organic combination of machine tools, tools and fixtures, etc. The teaching process of the course must have the corresponding practical teaching link with it, that is, the experimental teaching link. Through experimental teaching sessions, not only can digest and understand the theoretical knowledge learned in the classroom, improve their hands-on ability, and can train students to analyze and solve problems, for further study and graduate from the professional work to lay a solid foundation.
In teaching the “Fundamentals of Mechanical Manufacturing Technology” course, I found the following problems: First, the structure of the tool is abstract, and some of them are complicated.
First, the tool structure abstract, some complex tool structure is difficult for students to understand, this is the general problem of the experiment.
Second, the experimental teaching content is old-fashioned and boring, which does not stimulate the students’ interest in learning.
Third, students’ learning purpose is not clear enough, do not pay attention to the experimental teaching link, some students on the experimental class just to cope with, to get credit;.
Fourth, the experimental apparatus is aging and obsolete. Therefore, it is imperative to carry out teaching reform for the experiment of “Understanding and Measuring Geometric Angles of Tools” in “Fundamentals of Mechanical Manufacturing Technology”. In recent years, based on the analysis of the characteristics of this laboratory course, we have carried out reform and exploration in teaching contents and teaching methods, and applied it to undergraduate laboratory teaching, and achieved good teaching effect.
1 Reform of teaching content
Mechanical manufacturing is a profession with strong engineering and practicality, which emphasizes hands-on ability. The experimental teaching link is the main manifestation of its practicality, and students can give full play to and improve their hands-on ability through this link.
As the experiment class involves more tools, the structure of tools is more complex and abstract, and the experimental class time is limited, how to make students proficient in tool-related knowledge, tool measurement methods and strengthen the cultivation of students’ ability within the limited time has become the key to the reform of this experimental teaching.
Therefore, according to the characteristics of the experiment, combined with the current employment needs of students, the experimental lecture content made a superb selection, not only to ensure that students have a comprehensive understanding of the knife, but also focus on the knowledge that students will use in the future in the actual work.
In the process of teaching, it is crucial to develop a main line of the course and link the knowledge points together with this main line, so that the content of the experimental class becomes well organized and has a strong logic.
The content of this laboratory class is divided into three major parts: (1) the application of spatial stereo model to define the tool angle; (2) the recognition of typical tools and the introduction of angle; (3) the measurement method of turning tool angle and its labeling.
1.1 Application of spatial three-dimensional model
Since the tool angle is a spatial concept, here the spatial three-dimensional model is applied to introduce and explain to students the points, lines and surfaces that define the tool angle. The ‘point’ refers to the tool tip, the ‘line’ refers to the main cutting edge and the secondary cutting edge, and the ‘face’ involves two categories, one is the inherent face of the tool itself, which are the front tool face, the main rear tool face, the secondary back tool face; the other category is the 3 planes that need to be constructed in the tool angle definition, which are the base plane, cutting plane and orthogonal plane.
The tool angle is defined in these three planes for both simple and complex tools. With the help of this model, the angle of a common turning tool can be visualized in front of the students, making the difficult to understand spatial concepts visualized. The application of the model in the laboratory class not only simplifies the problems that are difficult to understand, but also enriches the content of the laboratory class and stimulates the enthusiasm of the students.
1.2 Introduction to typical tools and angles
Machining often requires machining surfaces such as external surfaces, hole machining, flat surfaces and complex surfaces. Depending on the surface to be machined, there are different types of tools. General external surface processing commonly used turning tools, turning tools are divided into: external turning tools, end turning tools, internal hole turning tools, cutting tools, grooving tools, etc.; hole processing to achieve many methods, different processing methods to complete different processes.
Commonly used are: drilling, reaming, reaming, boring and pulling holes, where drilling involves tools with twist drill, center drill, deep hole drill, etc. The reaming drill is similar to the twist drill, with more teeth and no horizontal edge. Reamers are used for reaming, and boring tools are used for boring; the common method for processing flat and complex surfaces is milling, which requires different milling tools for different surfaces. Different tools have their own tool angles, and their corresponding geometric angles can be found according to the definition of tool angles. In the laboratory class, the geometric angles of different tools are explained in relation to the application of commonly used tools.
1.3 Measuring and marking of turning tool angles
The angle of a turning tool is simpler than the angle of other tools, and in this experiment the geometric angle of a turning tool is measured with a universal angle table. Then use the adjustable part of the goniometer to find the position of the measuring plane and the position of each plane (or line) that constitutes the angle to be measured, and the geometric angle of the turning tool can be measured according to the experimental measurement method.
2 Improvement of teaching methods
2.1 Application of multimedia technology
In the past, the traditional teaching methods were mostly teacher-based fill-in-the-blank teaching, which was dull and boring to students and did not stimulate their interest in learning. In view of the characteristics of the experiment: the angle of some tools space three-dimensional is very strong, and these abstract problems only by the teacher to explain, it is difficult for students to digest and understand. The above problem is solved by integrating multimedia technology into the experimental class. The combination of graphics, animation, video and other multimedia together makes the typical tool structure come alive in front of the students, which not only deepens their knowledge and understanding of the tool structure, but also stimulates their interest in learning, making the boring class lively and interesting.
2.2 Interaction between teaching and learning
The traditional teaching method of experimental class is that the teacher guides students step by step according to the experimental steps, and the whole class is carried out according to the rules and regulations planned by the teacher [4-5]. Ultimately, students just follow the teacher’s method to come up with an experimental result, and it is not very clear how and why the experiment is done. It is difficult to give full play to students’ intelligence in this way of teaching and limited in terms of improving their hands-on skills. Based on this, and considering that the experiment is not a safety hazard, we propose an interactive teaching-learning model.
First of all, before doing the experiment, students are assigned to review the experimental content after class, and then the experimental class is first reviewed by the teacher and students on the theoretical knowledge of the laboratory class, while the teacher introduces the structure of the instruments and equipment used in the experiment, working principles and methods of use, this part can be regarded as the experimental “preamble” link, the experimental preparatory work are After completion, students will be divided into two groups, each group of 8 people, in each group elected student representatives to explain the experiment, the rest of the students do it themselves, to achieve the interaction between teaching and learning.
After the experiment was completed, each student who did the experiment was asked to talk about his or her experience and what could be improved in the experiment class, and finally the teacher summarized the class situation. After several rounds of classes, the teaching method has achieved excellent results!
After several sessions of experimental teaching practice, we have been exploring the teaching rules of the experimental class “Geometric angle of tool recognition and measurement” in the “Fundamentals of Mechanical Engineering” class, using various teaching concepts and teaching methods, consistently insisting on the organic combination of theory and practice, vigorously stimulating students’ interest in learning, motivating them to learn, and fully broadening their horizons. We have been able to stimulate students’ interest in learning, motivate them to learn, broaden their horizons, give full play to their creativity, greatly improve their hands-on ability and cultivate their sense of innovation. The quality of teaching and the effectiveness of teaching have been greatly improved.