Metal-cutting machine tools in the mechanical parts such as gears, worm gear, lead screw nut and so on, due to transmission of torque, the role of pressure, resulting in wear and tear and damage to machine accuracy and performance degradation, affecting the quality of the workpiece processing: as well as equipment failure, downtime regular repair, reduces the effective working hours, the impact of productive efficiency: some parts due to congenital defects in design, sometimes as is repaired, the result is not good, therefore, must be improved to enhance the service life of machine parts.
Machine tools in the repair, there was no simple repair as is, but a concrete analysis of specific situations, for different parts of the state of damage, repair to develop a detailed program for those vulnerable parts from the material selection, structural measures taken to improve the two aspects, Parts made to improve the life of the good results. Following are some examples to illustrate this.
1 material selection
We have encountered many maintenance machine parts are damaged as a result of materials, heat treatment process caused by improper selection, such as:
X53T milling, T618 boring main drive gear box X53T milling, T618 boring machinery manufacturers in the use of very common, these two problems is the largest machine tool from the main spindle motor to the main transmission case between the gear teeth often collapse, for which often stands repair, the production of large losses.
Previously, most enterprises use to change the transmission chain from the point of view, the structure drastically change, although the results have been received, but the heavy workload, the time and effort involved. Our analysis of the two machine tool gear tooth is broken, then that these gear module m = 3 ~ 4mm, the strength of the design parameters can have a broken tooth is mainly due to the intermittent processing of cutting force when the trigger vibration caused by the impact of: the original machine most of gear materials selected for the 45 steel, the Ministry of teeth to deal with high-frequency quenching, due to lack of tooth root strength by impact fracture, and even the use of a week or so the gear was broken.
Find the reasons, we made the following test, still using 45 steel manufacturers, but improved technology, forged gear blank Rough → → → quenched semi-refined car pull spline hole → → → Finish rolling before shaving shaving gear → → high-frequency quenching (tooth), which is the key to process crude, refined, together between the increase of quenching and tempering heat treatment process, so that parts of the overall intensity increased and, of course, increased the strength of the tooth root. By the processing conditions in the same trial, the processing of gear, as soon as possible can be used for three months, the longest available for about a year.
To further enhance the strength and life of gear, we have chosen to create 20CrMnTi gear alloy material, heat treatment for the carburization quenching process, tooth hardness 58 ~ 63HRC, through the use of more than a decade, has yet to produce the phenomenon of collapsing teeth, broken tooth problem solved .
Y38-1 take-off and landing gear-hobbing machine tool leadscrew nut tool Y38-1 hobbing screw-nut pairs of take-off and landing, the original screw steel with 45 made by quenching and tempering treatment, nuts with gray cast iron HT200 manufacturing, two shifts of production to about half a year time, due to wear and tear on the need to replace a large quantity.
We try QSn6-6-3 cast brass nut manufacturer, also available only for about a year. To this end, we analyzed the movements hobbing tool of power screw nut, the nut-shaped lateral teeth not only have to bear a lot of cutting force, but also to bear the weight of tool, while gray iron and QSn6-6-3 Brass low tensile strength, so wear quickly, we must choose兼优wear resistance and mechanical strength of the material, ductile iron possess the advantages of these two.
After analysis, we selected QT60-2 ductile iron, and its strength is QSn6-6-3 of 4 times, using it to produce nuts. By the actual use to prove that greatly increased life expectancy, you can use more than 5 years, and the cost of materials only QSn6-6-3 copper 1 / 6.
In the actual repair and replacement of many examples of selected materials, the two just to illustrate it. But bearing in mind that different machines in different parts of the mechanical parts, it is necessary to carry out a full analysis, first of all to meet the functional requirements of the original machine, then have to pay attention to economy, to reduce costs, it can be played to use the material effectively. Note that for a number of machine tool equipment was originally designed to use parts of the insurance is not free to change the materials and to improve their strength, otherwise it will create equipment accidents, personal accidents.

1. Screw 2. Nut Block
3. Nut 4. Straddle screw
Figure 1
1. Screw 2. Nut Block
3. Nut 4. Fastening nut
Figure 2
2 to improve the part structure
As a result of the original structural design of machine parts unreasonable that the use of these parts are often damaged in such a situation is not uncommon. Improve on them in repair, spare parts can also be played to enhance the effectiveness of life. Chamfering machine, such as the original YB9332C nut seat design as shown in Figure 1. Straddle screw out of the frequent damage to enable the nut, resulting in failure. To this end, we plot 2 shows its structure improvements. Thus, from the nut completely solved the problem of failure to prevent a repeat happen again.
To sum up, repair and improvement of machine parts to the structure of a combination of materials and to reduce equipment failure rates, extending the service life.