Justification of the choice of means of controlling the parameters of the crankshaft after processing for the repair size

. An assessment of the quality of the control of the parameters of the crankshaft after processing for the repair size was carried out. The company's metrological support system must guarantee the accuracy and quality of the crankshaft repair, eliminating the possibility of defects during subsequent assembly. When repairing engines, defects in the crankshafts are detected, after which they are replaced with new ones or processed according to the repair size. After processing the crankshaft for the repair size, it is necessary to carry out control according to six parameters. It was revealed that to measure the diameters of the main and connecting rod necks of the crankshaft of the Zavolzhsky Engine Plant, as well as their ovality, it is necessary to replace the micrometer 50-75 (0.01) used at the enterprise, the maximum measurement error of which is twice as large as permissible, with a lever bracket 50-75 (0.002) to reduce the measurement error and improve the quality of control. To control the greatest beating of the second, third and fourth root necks relative to the first and fifth root necks, the hour-type indicator used at enterprises fully satisfies the specified conditions, the maximum error does not exceed the permissible one. To control the axial clearance of the already assembled crankshaft along the thrust bearing, dial indicator 0-10 (0.01) is also used, which provides the specified measurement accuracy with a three-fold margin. When measuring the length of the third root neck, the use of a caliper calipers 0-125 (0.05) leads to an excess of the permissible measurement error by 3 times, but there are no other more accurate universal measuring instruments to control this parameter, since the control is carried out by special sponges for measuring holes, which are available only for calipers. It is recommended to design a gauge to measure the length of the third root neck.


Introduction
In connection with the growing demands of consumers of repair services, repair enterprises are strengthening quality control by introducing quality systems [1,2], designing and standardizing control operations [3,4].This also applies to enterprises involved in the repair of domestic machines [5,6,7], where it is necessary to improve the quality of control services [8,9], comply with the requirements for testing parameters of finished products [10], and also ensure the tolerances specified in the technical documentation and fit parts in repaired units [11,12,13].
The enterprise's metrological support system must guarantee the accuracy and quality of repairs to the crankshaft of the ZMZ engine, excluding the possibility of defects during subsequent assembly [14].The control accuracy must be at a high level, especially when monitoring worn shaft elements during defects and after processing the crankshaft journals to the repair size.The higher the control accuracy, the lower the likelihood of defects and associated losses.Universal measuring instruments used at repair enterprises, as a rule, have sufficient accuracy for high-quality performance of the necessary measurements [15,16], including operations for monitoring the shape and location of surfaces [17,18].We will check the compliance of the measuring instruments used to control the specified dimensions.

Materials and methods
The purpose of this study is to assess the quality of control of the crankshaft of the engine of the Zavolzhsky Motor Plant, which was processed to repair dimensions.For this purpose, data analysis methods and statistical indicators such as mean, variance, standard deviation, etc. are used.It will be used to determine the degree of compliance of the crankshaft parameters with the required standards and specifications of the Zavolzhsky Motor Plant.In addition, in order to establish the competitiveness of the products, a comparative assessment of the quality of control of crankshafts produced at other automotive enterprises of the industry will be carried out.
The result of the study will be the identification of possible shortcomings and improvements in the repair of crankshafts of the Zavolzhsky Motor Plant, which will improve their quality and competitiveness in the market.
The crankshaft of the engine of the Zavolzhsky Motor Plant model 409.10 was taken as the object of the study.
The study used the basic principles of the theory of accuracy and interchangeability of parts and connections, as well as the provisions of regulatory documents on the choice of linear dimension measuring instruments (RD 50-98-86).
As a result of the study, an assessment of the quality of control of the crankshaft of the engine of the Zavolzhsky Motor Plant model 409.10, which was processed to repair dimensions, was obtained.
The results obtained allowed us to identify some shortcomings in the repair of crankshafts of the Zavolzhsky Motor Plant.Deviations from the required standards were identified, which may affect the quality and competitiveness of products.These disadvantages may be related to the technological processes used at the enterprise, or to the quality of materials used in the processing of crankshafts.
To improve the quality and competitiveness of the products of the Zavolzhsky Motor Plant, a comparative assessment of the control of crankshafts produced at other automotive enterprises of the industry was carried out.This made it possible to determine how competitive the manufactured crankshafts are, and to identify potential improvements in the process of their repair.
Based on the results of the study, it is recommended to make certain changes in the process of repairing the crankshafts of the Zavolzhsky Motor Plant.This may include the improvement of technological processes, the introduction of new methods of quality control, as well as increasing the requirements for the materials used.Such changes will improve the quality of the crankshafts and ensure their compliance with the required standards and specifications.
In the future, it is planned to conduct additional studies in order to verify the effectiveness of the changes made and assess their impact on the competitiveness of products.It is also possible to extend the study to other engine parts and components in order to provide a more complete understanding of the quality and production processes at the enterprise.
In general, this study is an important step in improving the quality and competitiveness of the products of the Zavolzhsky Motor Plant.This makes it possible to identify problematic issues and identify areas for further improvement of production processes.

Rresearch results and their analysis
When the engines are received for repair, defects in the crankshafts are detected, after which they are replaced with new ones or proceed to the operation of processing the root and connecting rod necks for the repair size.After processing the crankshaft necks for the repair size, it is necessary to check it in accordance with six parameters.In addition to the diameters of the crankshaft necks, the shape deviation is controlled by the ovality of these necks, and using the same tool as the diameter meter.It is also necessary to control the deflection of the crankshaft, which is determined by the beating of the intermediate root necks relative to the extreme ones.The main controlled parameters during the repair of the crankshaft of the engine of the Zavolzhsky Motor Plant model 409.10 are presented in Table 1.
After the operation of processing the crankshaft necks for the repair size, six parameters must be checked.Important characteristics that need to be checked are the diameters of the crankshaft necks, the ovality of these necks and the deflection of the crankshaft.
To control the diameters of the crankshaft necks, a special tool is used to measure the exact values of these parameters.The permissible deviations from the standard dimensions are indicated in Table 1, which presents the main controlled parameters during the repair of the crankshaft of the engine model 409.10 of the Zavolzhsky Motor Plant.The dispersion of the sizes of the root and connecting rod necks is shown in Figures 1 and 2.  However, in addition to the diameters of the necks, it is also important to control the ovality of these necks.Ovality may occur as a result of wear or deformation of the crankshaft.To control the ovality, the same tool is used as for measuring diameters.If a significant ovality is detected, the crankshaft must be replaced to ensure proper engine operation.
In addition, it is necessary to control the deflection of the crankshaft.The deflection is determined by the beating of the intermediate root necks relative to the extreme ones.For this purpose, special equipment is used to measure the deflection with high accuracy.If the deflection exceeds the permissible values, the crankshaft also needs to be replaced.The whole process of checking the parameters of the crankshaft is an important part of the repair work.This allows you to check the correct geometry and condition of the shaft, which, in turn, ensures reliable and efficient operation of the engine.After successful inspection and elimination of all defects, the crankshaft can be installed back into the engine, ready for use.
Based on the presented table 1, it can be concluded that the tolerances for processing the main and connecting rod necks are 19 microns, which corresponds to the sixth accuracy standard.In repair production, worn-out metal-cutting equipment is usually used [19,20], including for processing crankshafts to sizes that require repair.Because of this, achieving the specified accuracy may become problematic [21], since the size of the scattering zone may exceed the permissible one.Therefore, it is important to ensure the specified measurement accuracy [22,23].In addition, it should be taken into account that the use of more accurate measuring devices can lead to economic benefits by reducing the level of defects [24,25].
However, it is important to note that there are ways to improve the accuracy of processing and measurements in repair production.Firstly, it is possible to carry out regular maintenance and calibration of metal-cutting equipment in order to minimize its wear and maintain its operability at an acceptable level.This will allow for more precise processing and reduce the size of the dispersion zone.
Secondly, it is worth considering the possibility of using more modern and precise equipment specifically designed for repair work.Such tools can be equipped with more accurate measurement and control systems that will ensure the specified accuracy when processing crankshafts.
In addition, it is important to pay attention to the training and qualifications of personnel working with metal-cutting equipment.The correct use of tools and processing methods can significantly affect the achievement of the required accuracy.Conducting specialized trainings and training programs will help improve the skills of employees and provide more accurate results.
Thus, although repair production often faces accuracy problems due to the use of wornout equipment, there are methods and approaches that can improve the accuracy of processing and measurements.This includes regular maintenance of equipment, the use of modern tools and staff training.The application of these measures will help to achieve the required accuracy and reduce the level of defects, which will lead to economic benefits for the enterprise.
The means of measuring the parameters of the crankshaft of the engine of the Zavolzhsky Motor Plant during repair are presented in Table 2. From the presented Table 2 it can be seen that the maximum error in measuring the diameters of the main and connecting rod necks with a micrometer MK 75-0.01 exceeds the permissible measurement error by two times.This means that using this micrometer may lead to inaccurate results and incorrect measurements.
In such cases, it is recommended to use the MK 75-0.002lever bracket, which has a smaller measurement error -only ± 2 microns.This is significantly less than the maximum error of the micrometer MK 75-0.01, and allows you to get more accurate results.
The MK 75-0.002lever bracket can also be used to measure the ovality of necks after grinding them.The ovality of the necks is an important parameter that must be controlled during the manufacture of parts.Using a lever bracket will allow you to more accurately determine the ovality of the necks and make sure that the part meets the required standards.
The use of the MK 75-0.002lever bracket is more preferable in this case, since it provides a smaller measurement error and allows you to get more accurate results of checking the diameters of the necks and ovality after grinding them.This is important to ensure the quality of production and compliance of parts with the required standards.
At enterprises where the production of crankshafts is carried out, monitoring their quality and compliance with the specified parameters is an important task.To do this, an ICH 10-0.01 clock type indicator is used, which allows you to control the largest beating of the second, third and fourth root necks relative to the first and fifth root necks.
The ICH 10-0.01 indicator is a reliable and accurate tool that allows you to measure the heartbeat with high accuracy.Its use in enterprises ensures that the crankshaft has the necessary characteristics and meets the requirements.
In addition, the same indicator is used to monitor the axial clearance of an already assembled crankshaft on a thrust bearing.It provides the specified measurement accuracy with a three-fold margin, which allows detecting even the slightest deviations from the required parameters.
Thanks to the use of the ICH 10-0.01 indicator, a high level of quality control of manufactured crankshafts is achieved at enterprises.This allows you to prevent possible defects and confidently produce products that meet all requirements and standards.
In addition, the ICH 10-0.01 indicator has a simple and convenient design, which facilitates its use in production.It is securely attached to the crankshaft and allows the operator to make measurements quickly and accurately.
It is important to note that the use of this indicator not only improves the quality of products, but also saves time and resources.Thanks to its use, possible defects can be quickly detected and eliminated, which reduces production time and avoids additional costs.
As a result, the use of the ICH 10-0.01 hour-type indicator at enterprises engaged in the production of crankshafts is an integral part of the quality control process.This ensures accurate measurements and ensures that the products meet all requirements and standards.
When it comes to measuring the length of the third root neck, the caliper SHC 125-0.05 is the most common tool.However, when using it, there is a problem with the measurement error, which exceeds the permissible value by 3 times.This means that the accuracy of measurements with this tool is limited.
Unfortunately, at the moment there are no other, more accurate and universal measuring instruments for monitoring this parameter.Control of the length of the third root neck is carried out with the help of special sponges, which are available only in the caliper.This limits the possibility of using other tools to measure this parameter more accurately.
In light of this, it is recommended to develop a specialized gauge for measuring the length of the third root neck.Such a caliber will be specially designed and manufactured for these purposes, providing more accurate measurements.This will improve the control of the length of the third root neck and reduce the measurement error.
It is important to note that the development and production of such a caliber may require additional costs and efforts.However, this will be justified, given the importance of controlling the length of the third root neck in various fields, such as mechanical engineering and the automotive industry.
Thus, the development of a specialized sensor for measuring the length of the third root neck is a recommended solution to improve the accuracy and reliability of monitoring this parameter.

Conclusions
Thus, an analysis of the quality of the process of measuring the parameters of the crankshaft machining field for the repair size showed that the ICH 10-0.01 clock type indicator used to control intermediate necks relative to the extreme ones, as well as to control the axial clearance of the already assembled crankshaft, fully meets the conditions for ensuring measurement accuracy.The maximum measurement error of the micrometer MK 75-0.01 when checking the diameters of the main and connecting rod necks is twice the permissible measurement error.It is recommended to use a lever arm MK 75-0.002instead of a micrometer, in which the measurement error will meet the requirements.It is also suitable for measuring the ovality of necks after grinding.For the purposes of controlling the length of the third root neck, it is recommended to design a caliber, since the caliper SHC 125-0.05exceeds the permissible error by three times.

Fig. 2 .
Fig. 2. Dispersion of the sizes of connecting rod necks.

Table 1 .
Controlled parameters during the repair of the crankshaft of the Zavolzhsky Motor Plant.
Fig. 1.Dispersion of the sizes of the root necks.

Table 2 .
Means for measuring parameters of the crankshaft of the engine of the Zavolzhsky Motor Plant during repairs.