When it comes to mechanical engineering, thread is one of the most frequently encountered geometric features, and it can be found in many different applications across a wide range of industries.  It is possible to process threads in a variety of ways, including by employing various technologies such as thread rolling (including plastic deformation-based thread rolling), turning (including milling), tapping (including threading), and thread grinding (including thread grinding).  Thread turning is one of the most frequently used machining techniques in single-piece or small-batch production, and it is described in greater detail below.  Thread turning is one of the most fundamental functions of a CNC lathe, and it is also one of the most difficult functions to master on one of these machines.

Thread NC machining differs from contour NC machining in that it is more precise.  Thread NC machining is also more expensive.  Threading is accomplished through the use of numerically controlled (NC) machining.  To name a few of its characteristics, it has the following characteristics:Creating threads with a machining center is a subset of the process of forming machined parts.  Unlike the cutting edge of a chisel, which is long, it is easy to gnaw and stabbing, necessitating the use of several different cutting tools.  In order to ensure accurate lead (or pitch) measurement, cutting in and cutting out lengths that are appropriate for the job must be used.  Because of the way the tool is designed and manufactured, it is virtually guaranteed that the thread profile and profile angle will be achieved during the thread machining process.  This means that the shape of the tool and how it is installed have an impact on the quality of the thread profile that is produced by it.  The feed rate and spindle speed must be kept within a specific range in order to maintain a strict transmission ratio during thread processing.  This range can be represented by the equation f = pH (mm / R).  As a result of this restriction, constant linear speed control is not permitted during the processing phase.  The cutting speed is relatively slow during the thread cutting process, which is based on the principle of no chip accumulation or tool plastic damage occurring during the cutting process. 

 

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It is common in the thread-turning process to find yourself having to reinstall and adjust the tool due to wear and tear on the thread-turning tool, as well as tool collapse, during the process.  It is essential to note that the accuracy cnc turning china of thread turning is directly related to the quality of tool installation and tool adjustment, with the latter being of the greatest importance.  As previously stated, the repair and turning of threads necessitate the use of secondary clamping and secondary tool adjustment.  As a result, the machining efficiency of thread machining performed on a numerically controlled lathe is significantly reduced.  In order to achieve high thread accuracy requirements, such as when the two sides of a trapezoidal thread need to be finished, it may be necessary to change the fine turning tool after rough machining to finish machining after roughing.  Numerically controlled thread turning will be ineffective unless and until the issues of tool loading and tool setting in the machining process are adequately addressed.

It is the purpose of this chapter to introduce the fundamentals of thread machining on a numerically controlled lathe.

NC Turning Thread has a distinct appearance that distinguishes it from ordinary lathe turning thread, which is immediately noticeable.  With each revolution of the spindle of an ordinary lathe, a lead screw is moved in the opposite direction by a gear mechanical transmission.  During the thread processing process, this transmission chain cannot be disconnected at any point; otherwise, the thread will become buckled, and the thread will break.

To turn a spindle using NC turning, a pulse signal is transmitted from a position encoder on the spindle to the NC system, which allows the spindle to rotate.  This machine is controlled by a numerical control system (NC system), which regulates machine operation and sends instructions to the servo motor, which controls the movement of the tool through the ball screw in order to achieve thread-turning results.  Due to the fact that the initial machining position of the thread is controlled by the detection of the pulse signal, it is necessary to ensure that the thread turning does not buckle disorderly during multi-tool walking in order to avoid this from occurring.  Upon initiation of program processing, the spindle begins to rotate, and the tool comes to a complete stop until the spindle encoder sends out the synchronization signal (zero position signal), which is received by the tool and allows it to resume turning.  After receiving the synchronization signal (zero position signal), the tool will either return to the starting point of the previous turning or turn again to ensure that the turning thread is always on the same helix when the second tool thread is turned, and when the tool thread is turned, when the tool thread is turned.  This means that in this situation, there will be no opportunity for deduction.

When thread turning is done, it is possible to have issues with the tool setting.

Prior to anything else, the clamping tool needs to be rotated.

Once a thread cutter is clamped to a workpiece for the first time, it's common to notice that there's a noticeable height difference between the thread cutter tip and the rotation center of the workpiece.  This is completely normal.  The majority of the time, it can be found in welding cutters, where it can be useful.  In order to compensate for rough manufacturing and inaccurate cutter rod size, the center height must be adjusted with shims after the turn is completed.  Additionally, the center height has an effect on the actual geometric angle after the turn is completed.  You should be aware that when you first install a new cutter, cnc milling parts is very easy to introduce a thread profile angle error as well as a tooth profile skew into the thread profile because the tip angle of the cutter is biased.  Because it vibrates during the machining process, if the thread cutter is left in place for an excessive amount of time, the surface roughness of the thread will be impacted negatively.

2) Selecting the most appropriate rough and fine turning tools for the job.

Using two thread cutters to separate your rough and fine turning will ensure that you achieve the best possible results when threading or trapezoidal thread machining.  This will assist you in achieving the best possible results.  As a result of the offset between the two cutters, thread scrapping will occur due to an increase in thread pitch diameter as a result of the increased thread pitch diameter.

3) Design of the repair workpiece tooling for the repair job

Configuration of the tooling for the repair workpieceA disorderly buckle will occur again during the repair and processing of the workpiece as a result of the secondary clamping of the workpiece, which has caused the repaired helix and the first rotation signal of the encoder to change.

Identifying issues and determining appropriate solutions

In order to ensure proper threading, the thread tool tip must remain at the same height as the central axis of rotation of the workpiece throughout the threading operation.  The tool setting template should be leaning against the workpiece axis to be set after it has been ground in order to ensure that the tool tip angle is installed in the proper position. . It is generally possible to clamp the tool using a numerical control (NC) machine because of the high manufacturing accuracy of the tool bar.  This allows the tool bar to be placed close to the side of the tool holder, which reduces the risk of tool damage.

Mark a specific point on the workpiece that will serve as a reference point before starting the rough and fine machining thread cutter setup process.  Then follow the standard operating procedures for the thread cutter setup process.  When it comes to the actual tool setting procedure, the trial cutting method is used as long as the tool compensation is only marginally different from the initial setting.

Secondly, if the thread machining tool becomes worn or broken during the thread machining process, it is necessary to reset the tool after it has been re-sharpened to prevent further damage.  As long as the workpiece is not being removed for repair, it is only necessary to align the thread cutter's installation position with the position before removal; otherwise, it is equivalent to machining the workpiece with the same turning tool.

The repair processing can only be completed successfully after the machining starting point position of the disassembled workpiece has been determined for the cnc machining services workpiece.  The test rod can be used for thread turning with surface depths ranging between 0. 05 and 0. 1mm and a surface depth of 0. 1mm to determine the starting point of the machining process and the location of the one turn signal, respectively.  A spiral line is engraved on the surface to indicate where the thread turning process begins.  The integer thread lead distance from the right end face of the thread starting point is represented by Z, and the spiral line indicates where the thread turning process begins.  In the following step, make a mark on the circular surface of the chuck at the appropriate location along its circumference. 

 

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A record of the signal position is made, the test bar is removed, and the threaded workpiece is clamped to allow it to be turned or repaired after the signal position has been recorded.  Consider the following example: When positioning a tool for machining, begin by turning the tool to the machining position first.  Then, with the turning tool in the scoring position of a collet chuck, rotate the chuck until the main cutting edge of the turning tool is aligned with the scoring position.  Continue to move the tool tip to any complete thread groove while recording the corresponding Z-direction absolute coordinates, while maintaining spindle stability, and so on.  Plan out your calculations for the turning tool's starting point Z-direction positioning coordinates, and then modify the turning tool's starting point Z-direction positioning coordinates in the program to reflect the results of your calculations, as necessary.

Thread turning is a precision operation in which every step, from loading the tool to setting it, is critical.  This is especially true when it comes to the secondary thread turning stage of the operation.  It is critical to ensure that the spindle's zero position signal position corresponds to the starting point of the existing thread helix on the workpiece in order for the thread groove to be turned on the workpiece before the thread groove can be turned.  The thread groove will not be turned if this is not done.