No matter in school or in society, everyone will inevitably come into contact with papers. With the help of papers, we can discuss problems and conduct academic research. So how to write a general paper? The following are my collected papers about machinists and fitters. Welcome to reading. I hope you will like them.

Abstract: Fiddler is a traditional manual labor with a history of more than 2,000 years. In recent years, with the continuous development and progress of science and technology, many fitter processes have been mechanized, but the processing operation of assembly fitter still plays an irreplaceable role and is an indispensable work in mechanical manufacturing. The basic technical points of assembly fitter are briefly introduced.

Keywords:: assembly fitter technical points

Compared with machining, locksmith has higher operation intensity, lower chemical precision and lower efficiency. In machining, many machining processes that are difficult to be completed by machinery are completed by fitters, which is essential for some special parts manufacturing, especially assembly fitters, and has a great influence on the quality and performance of products. Therefore, it is necessary to master the technical points of the fitter, strictly follow the process regulations in the production process, and ensure the product quality.

1 Basic skills of assembly fitter

1. 1 underscore

According to the drawings and actual processing requirements, draw corresponding points, lines, surfaces, etc. Draw the boundary as the machining reference on the blank or semi-finished product with the marking tool. The scribing operation must ensure that the scribing or scribing points and surfaces are clear and the size positioning is accurate, so as to ensure the machining accuracy. Generally, the scribing accuracy is required to be between 0.25 and 0.5 RAM. By marking, the machining allowance of the workpiece can be determined more intuitively, and the machining size limit is clear at a glance. At the same time, unqualified workpieces can be found and handled in time. Marking needle, marking gauge, steel rule and marking disk are common tools for marking operation. In the process of using the marking tool, in order to avoid scratching or damaging the tool and ensure the marking accuracy, try to keep a certain distance between the marking tool and the blank. In addition, we should pay attention to the maintenance of marking tools and deal with rust and dirt in time.

1.2 archiving

Archiving is widely used. It can not only file flat surfaces and curved surfaces, but also file complex internal and external surfaces with different shapes, such as grooves. The filing accuracy can reach 0.0 1 mm, and the operation method is very important when filing. Generally, the right hand holds the handle, the palm supports the handle end, the thumb presses the upper end of the handle, and the other four fingers hold the handle tightly. Hold the front end of the file with the middle finger and the ring finger of the left hand, and press the head of the file with the thumb, so that the index finger and the little finger naturally meet. When operating, pay attention to control the center of gravity, stand naturally, make the file in a state of horizontal linear motion, and control attention at the same time. The file frequency is generally about 40 min.

1.3 sawing

As the name implies, sawing is the process of sawing a workpiece with a saw. When operating, the right hand holds the handle of the saw bow, the thumb presses the index finger, and the left hand controls the direction of the saw bow. The left thumb is pressed on the back of the bow, and the other fingers hold the front end of the saw bow. In the process of pushing the saw blade, the left hand is kept up and the right hand is pressed down hard. On the return trip, the right hand is raised and the left hand is followed by the saw bow. The frequency of sawing is basically the same as that of filing, about 40 times per minute. It is worth noting that when sawing, the force should be controlled to avoid breaking the saw blade with excessive force and hurting the human body; The vertical direction of the eye and the saw blade coincides to ensure straight-line processing and sawing; When installing the saw blade, avoid breaking the saw blade with excessive force.

1.4 drilling

In order to ensure the accuracy of drilling, the center line of the cross should be drawn at the target position before drilling to determine the specific hole position. At the same time, the center template should be perforated to make it coincide with the center line of the cross. If there is any deviation, it should be corrected in time. When drilling holes, the machining size of punching holes should be as small as possible. When machining holes with small diameter or large depth, it is necessary to reduce the feed of the drill bit as much as possible, and at the same time, it is necessary to continuously retract and cut to avoid damaging the drill bit by pressing and plugging the hole. When the drilling hole is about to penetrate, reduce the feed force of the drill bit, reduce the cutting resistance and prevent the occurrence of safety accidents caused by the fracture of the drill bit. In addition, it is necessary to strengthen the heat dissipation measures of the drill bit, add an appropriate amount of cutting fluid when drilling, and minimize the friction on the drill bit, which will not only help to prolong the life of the drill bit, but also improve the surface quality of the hole. There are the following precautions when drilling: First, don't wear gloves when drilling, which is easy to cause safety accidents; Second, when drilling, inspection is not allowed. If necessary, stop the car first and then check it. Third, in order to prevent people from being injured by flat-nose pliers, the handle end should be placed on the left side of the drilling machine workbench; Fourth, when drilling a larger hole, drill it with a small bit first, and then use a big bit to enlarge the hole.

1.5 tapping

The process of machining internal thread in workpiece hole with tap is called tapping, for example, the thread to be machined is 4×M 10. At the beginning, the hole of C10.5 was chamfered with a point drill with a diameter of 18 mm, and then the bottom hole was drilled. The last step was tapping 4×M 10. Precautions for operation: 1. Tapping operation can only be carried out after chamfering of bottom hole orifice is completed; Second, ensure that the workpiece is clamped in a horizontal state; Third, check and correct the vertical position of the tap at any time during the tap cutting process to ensure the machining accuracy; Fourth, when there are obstacles in the taphole, exit the taphole in time and clean up the iron filings in the hole to prevent the taphole from being damaged or the processing depth from reaching the requirements.

2 Assembly of common measuring tools

Vernier caliper and dial gauge are two main measuring tools in assembly. As an indispensable measuring tool in the assembly process, vernier caliper can measure not only the length and thickness of the workpiece, but also the inner and outer diameter, hole depth and center distance of the hole. When using vernier caliper, first observe the integer near the zero dividing line of the ruler, and find out the dividing line that coincides with a dividing line of the ruler body from the zero dividing line. The product of the precision value and the value of this fractional line is the decimal part of 1 ram, and then the read integer and decimal are added up, and the result is the final measured value. When measuring with vernier caliper, the burr of the workpiece should be removed first to avoid scratching the caliper.

3 assembly drawing

Assembly drawing is an important reference in the process of mechanical manufacturing and an indispensable reference tool for assembly workers. The assembly drawing can fully reflect the designer's design intention and the working principle of mechanical parts. Designers show the assembly relationship, specific structure and actual situation of components through assembly drawings, providing reliable dimensions and technical indicators for assembly, inspection and installation. Therefore, before installation, we should fully understand the size and performance of the parts in the drawings.

The steps of assembly drawing are as follows: first, observe the content of title bar, and have a preliminary understanding of the function, name, material and quantity of parts. When encountering unfamiliar or complicated assembly drawings, consult relevant technical data and specifications to master the specific functions and structural characteristics of parts. Second, observe the research view, grasp the expression purpose of the assembly drawing through the front view, top view and left view, and clarify the relationship between the views. Third, further study the view and conceive the structure and shape in your mind. Fourthly, make clear the size requirements of the assembly drawing, study and analyze all the size requirements, and determine the specific form of size benchmark and size category marking on the premise of meeting the design process requirements to ensure the rationality of the assembly process. Finally, according to the technical requirements, the whole map is comprehensively analyzed and mastered.

4 Adjustment of axial clearance of rolling bearing

First of all, there is a certain gap (usually about 0.2~0.4 mm) between the two sides of the shaft through the centripetal bearing, and this centripetal shaft has an irreconcilable gap. Secondly, the axial clearance of the rolling bearing with adjustable radial clearance is not clearly defined in the drawing. Thirdly, the axial spacing of bearings is controlled by adjusting screws and nuts. In addition, the feeler gauge and dial indicator should be measured and adjusted. Fourthly, the adjustment of axial clearance of double-row tapered roller bearings. Fifth, the adjustment of axial clearance of four rows of tapered roller bearings.

Five points for attention during disassembly

According to the different actual structures, different disassembly sequences are adopted to clarify the main points of disassembly; Pay attention to the protection of tool parts when disassembling, and choose tools reasonably; Dismantled parts are placed in turn according to different models, nested together according to the original structure, and marked well.

6 conclusion

In a word, locksmith is a manual process with strict requirements on accuracy, and the operation needs to be carried out in strict accordance with the technological requirements. Therefore, while mastering theoretical knowledge, it is also necessary to accumulate experience in actual production practice and improve the mastery of technology to ensure product quality and production safety.

refer to

[1] sheets. Key points of fitter assembly technology [J]. Machining and manufacturing, 20 12 (iv): 15- 17.

[2] Li Zhenren. On the basic technology and operation of locksmith [J]. Heilongjiang Science and Technology Information, 2009 (9): 29.

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