Centerless grinding machine for centering grinding

The workshops specializing in cylindrical grinding and grinding processes often need to change the type of work. The workpieces are changed from inner diameter and outer diameter grinders to centerless grinding machines for processing. If you can understand the rationality behind this transformation, then you can determine where the centerless grinder can play its biggest role.

When a part is sent to the grinding shop, the part has been milled, turned, heat treated, and other operations. Each process will create more added value for the part, and each process may take longer than expected. In addition, there are competitive pressures from other advanced technologies. However, Mr. John Shegda, owner of M&S Hatboro Grinding and Processing Company in Pennsylvania, was confident in this, because that kind of work was only a matter of “hand in hand” for him. In fact, this kind of competition mainly comes from turning technology. At present, his processing workshop is in a thriving situation. Since 2006, his processing plant has expanded three-fold, and most of its processing equipment is being upgraded.

Most of the recent successes in this workshop have been attributed to the proper configuration of its resources. They know exactly when they should deploy their power, apply the newest centerless grinding technology to cylindrical grinding, and when they should adopt other methods. In order to maximize the high-precision machining level and profitability of the workpiece, the shop has made some adjustments to the processing normally associated with the outside diameter and inside diameter, converting the workpiece to the newly purchased throughfeed centerless grinding machine. In order to achieve this goal, the subcontractor of the grinding process demonstrated not only the most effective machining level of the centerless grinder, but also demonstrated the various functions of the current centerless grinder.

Figure 1 Monza 410 centerless grinding machine, which allows the shop to control the geometry of the parts with high precision, in order to achieve the processing requirements of high-end work. After completing this process, the following work is relatively simple

Due to the lack of understanding of the dynamics of this process, it is impossible to understand the astonishing power of high-precision grinding technology. However, Mr. Shegda abandoned this concept of grinding, so that this technology can play its biggest role. He and his 14 employees applied this type of grinding technology in a more logical way. They learned the analytical techniques and grinding knowledge left by Mr. Meron Shegda and started the business in 1957. Since 1990, Mr. John Shegda and Mr. Mark Shegda have been in charge of M&S. Mr. Meron Shegda is a chess and card lover. His interest in the game helped him further improve his analytical skills. Practice has proved that this ability is very beneficial to him in creating this business.

Mr. John Shegda said: "All we do and know is due to my father. He is the most intelligent person I know." In those days, the company's work was completely dependent on His ideas, as well as a variety of processing equipment, including CNC machine tools, automatic machine tools and manual machinery. The company's business scope includes various types of cylindrical grinding processes, mainly for the medical and aerospace industries. M&S can grind any kind of parts for these industries, including multiple processing steps, various angles, taper and radius. They have about 500 customers, including many machining workshops. They contacted M&S and asked them to help them rework, correct some parts out of roundness, and also require prompt delivery.

Since recognizing the performance of unmotivated grinding technology, M&S began to apply it to practice. In fact, the unmotivated grinding technology has further increased the confidence of the machining shop, enabling them to successfully complete the machining tasks according to the high precision roundness and tolerance size requirements.

Completing the complex work on demand is a task that Mr. Shegda and his staff need to accomplish. These high-precision machined workpieces range from about 1 to 10,000 parts. They require extremely high roundness and concentricity, with an accuracy of 0.02 in. (1 in = 25.4 mm).

Mr. Shegda explained: “For most of the new parts we undertake, the tolerances of diameter and roundness are very high (usually parts for the aviation industry), and some are even parts of the medical industry. The shape is very small, and the processing requirements are achieved. Amazingly."

Precision technology and basic principles

The centerless grinding process itself is not a problem for the grinding of such workpieces and will certainly be successful. Therefore, M&S will definitely adopt this processing method whenever possible.
Mr. Shegda explained: “The most important thing is that the speed of the unmotivated grinding is faster. Generally speaking, this kind of process itself has a higher processing accuracy, because the machine does not need to run at a very small incremental level. So we can Maximum control of tolerances."

One difference between centerless grinding and other cylindrical grinding processes is that the workpiece is not mechanically limited. Cylindrical grinding machines generally hold the workpiece in the top or chuck so that the workpiece rotates against the grinding wheel. The centerless grinding machine does not have any "center point" to hold the workpiece. It relies on the principle of grinding of the interaction forces between three key components, namely the grinding wheel, adjusting wheel and workpiece blade.

In the centerless grinding process, the workpiece blade is used to support the outer diameter of the workpiece. The workpiece blade is installed between the high-speed grinding wheel and the small-diameter, low-speed adjusting wheel. In order to achieve the purpose of turning and grinding the workpiece, the workpiece leaf must be installed in a position, that is, the centerline of the workpiece should be located on the center line of the grinding wheel and adjusting wheel.

About two years ago, the workshop made a strategic investment to further optimize the centerless grinding process. The workshop purchased a Monza 410 CNC CNC feed-through centerless grinder. Prior to this, the workshop had only six modified centerless grinders. Although the daily machining accuracy of these modified grinders can be maintained within the tolerance range of 0.0001 inch, it is impossible to meet the requirements of ultra-compact tolerances because these parts processing requirements are presented to them by the medical and aviation industries. of. In order to accept more high-precision machined parts, the workshop also added a Monza 310 type feed-through centerless grinder for the machining of flat head pins, flat head reels, and micro medical device parts up to 0.020 inches in diameter.

Mr. Shegda said: “If we had to work on machine tools for dimensional accuracy of roundness, flatness or diameter, then we would not be able to effectively handle this demanding high-end part. Monza's centerless grinding machine allows us to be more precise The level of control of the geometric accuracy of parts, to meet the processing requirements, reduce the complexity of the workpiece processing.However, the work of this nature is still not so easy to complete.But we can at least solve the problem of the parts themselves, rather than Deal with the limitations of equipment."

For the processing plant, part of the value of the new grinding machine lies in its ability to quickly commission settings. In fact, the operator can generally complete the basic debugging setup for centerless grinding of workpieces within 15 to 20 minutes. The ability to quickly set up workpieces on old machine tools and on Monza Centerless Grinding Machines is critical for M&S, because each machine tool may require 6-8 assembly checks per day.

Mr. Shegda said: “If it is based on the nature of our work and the number of constant commissionings that match it, it will be realistic for us to spend only 1 hour to complete everything.”

M&S is not relying too much on clever arrangements. Instead, it uses the Monza 410 type infeed grinders to complete its work. Due to the "reinforcing correction" feature of this machine, it allows the operator to adjust and correct the diameter size during operation of the machine.

The roundness, type, condition of the grinding wheel and the amount of material to be cut are also important factors affecting the commissioning setting. The reason why Mr. Shegda wanted to configure a feed-through centerless grinding machine was to have a "back-up" size in a precise workpiece machining process.

Mr. Shegda explained: “The worst thing that can be done to maintain the dimensional consistency is to stop using the feed-through centerless grinder. In order to effectively achieve the incremental accuracy of 0.000 01in, we can do it in Monza 410. The centerless grinding machine precisely controls the size without stopping the machine."

In addition to understanding the basics of a centerless grinder and properly evaluating the equipment required to perform a process operation, the staff in the processing plant must also understand the proper configuration of the equipment, which has a great influence on the profitability of the workshop and the overall effectiveness of the work.

Even if the workshop thinks that the outer diameter grinding is the best processing method, the roundness of the processing by this method can reach the level of 10 to 20 in parts per million. Compared with other methods, the accuracy can be kept high. This method is not necessarily suitable for all incoming processing. Mr. Shegda found that some customers often mistakenly believe that they only need the kind of grinding between the thimble, but in fact, what they need is the machining capacity of the centerless grinder. For example, the use of an outside diameter grinding process may cause problems for parts with a large length and diameter.

Fig. 2 For workpieces with a relatively large length and diameter, a centerless grinding machine is used, such as the one shown below.

Mr. Shegda explained: “If you need grinding parts that are very long and thin, then cylindrical grinding is more difficult. On the contrary, using a centerless grinding machine is handy. If a part has a diameter of 0.250in and a length of 10in, The total tolerance of the outer diameter to be machined is 0.0001 in. Processing on a cylindrical grinding machine will become a “nightmare.” If the part has a flat head on it, we can use a feed-through centerless grinding machine, grinding will be It is simpler and easier, and can even be processed on a larger infeed machine.The key is that the part must be supported on three sides: the carbide alloy blade is in the lower part, the adjustment wheel is on the side, and the grinding wheel is in another As long as these three supporting surfaces are in the normal position, theoretically speaking, grinding and processing a straight round bar should not be too problematic.Of course, the theory is very different from reality. If you really understand the part you are working on, you will be able to achieve very high tolerance dimensional accuracy.”

The pursuit of more challenging grinding processes indicates that this process is required to compete and compete with hard turning operations. For centerless grinding, the main competition is not from other grinding shops, but from other competitive technologies.

Mr. Shegda explained: “We consider hard turning to be a strong 'competitor' because the current machining shop can efficiently machine heat-treated steel workpieces with machining accuracy up to 0.0005 in. in many cases. Even higher precision machining can be achieved, and in order to develop and expand our business, this process actually allows us to shift to more discerning and more challenging work.Now, only those who can achieve high precision and high quality Work and breakthrough technologies that are in line with the times will be successful."

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