JP2019188554A - Method for thread cutting process and machine tool - Google Patents

Abstract

To effectively hinder chattering vibration in a thread-cutting process including a finish process.SOLUTION: A method for a thread cutting process is performed by repeating, more than one time, a path or a cycle including: allowing a cutter to radially cut into a work W while rotating the work W at a predetermined rotational speed, feeding the work W in a rotary shaft direction to perform a process for a thread part, and allowing the cutter to radially move away. In the method, in a process at least one path before a finish process, processes for flanks different from each other are simultaneously performed by using two cutters: one cutter, or a first cutter 10, for single-edged cutting and the other cutter, or a second cutter 20, for reverse single-edged cutting. Thereafter, a finish process is performed using one cutter to perform right-angle cutting process.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a threading method capable of suppressing chatter vibration and a machine tool capable of executing the method.

Two turning tools are used in the turning process, and the arrangement of the two cutting tools around the rotation center axis is shifted relative to the 180 ° balance arrangement, thereby regenerating by canceling the regenerative effect that occurs at each cutting edge. A technique for suppressing chatter vibration is known (see Patent Document 1).
On the other hand, in threading, there is known a threading method in which only one ridge line of two cutting edges of a cutting tool is cut into a work material (single blade cutting, reverse single blade cutting).

JP 2017-127960 A

According to the turning method of Patent Document 1, chatter vibration can be suppressed by offsetting the regeneration effect of the first cutting tool and the second cutting tool in round cutting. However, in the threading process, the regeneration effect exists on the machining surface one pass before for the first cutting tool and the machining surface generated by the current first cutting tool for the second cutting tool, so that the regeneration effect is effectively offset. I can't.
On the other hand, according to single-edged cutting and reverse single-edged cutting, since the cutting width is smaller than that of a right-angled cutting that cuts all cutting edge ridgelines, chatter vibration can be suppressed. However, in the finishing process, there is a case where it is desired to make a right angle in order to process the screw shape with high accuracy.

  Accordingly, an object of the present invention is to provide a threading method and a machine tool that can effectively suppress chatter vibration in threading including finishing.

In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that after the workpiece is rotated at a predetermined rotational speed, the cutting tool is cut in the radial direction, and the threaded portion is processed by feeding in the rotational axis direction. , A method of performing threading by repeating a pass of releasing the cutting tool in the radial direction as a cycle a plurality of times,
In machining at least one pass before the finishing process, two knives are used, one knives with one edge cutting and the other knives with reverse one edge cutting simultaneously with different flank machining. It is characterized by performing processing with a right angle cut using one of the two.
According to a second aspect of the present invention, in the configuration of the first aspect, the two cutting tools used in the processing prior to the finishing process are arranged so that one of them is 180 ° around the rotation center axis of the workpiece. The arrangement is characterized by being shifted by a predetermined angle that is an acute angle around.
According to a third aspect of the present invention, in the configuration of the first aspect, the two cutting tools used in the processing before the finishing process are arranged so that either one of the two cutting tools is positioned around the rotation center axis of the workpiece at 0 ° around the rotation center axis. The arrangement is characterized by being shifted by a predetermined angle that is an acute angle around.
In order to achieve the above-mentioned object, the invention according to claim 4, while rotating the workpiece at a predetermined rotation angle, cuts the cutting tool in the radial direction with respect to the workpiece, and sends the screw portion in the rotation axis direction. A machine tool capable of performing threading by repeating a pass of releasing the cutting tool in the radial direction multiple times as one cycle after machining,
The threading method according to any one of claims 1 to 3 can be executed.

  According to the present invention, two cutting tools are used at least one pass before the threading finishing process, and one cutting tool performs machining with a single blade cutting and the other cutting tool simultaneously performs machining with a reverse single cutting. Since different flank is machined, in the machining by the right angle cutting of the finishing pass, the regenerating effect of the single blade cutting before the one pass and the regenerating effect of the reverse single blade cutting can be offset. Therefore, chatter vibration can be effectively suppressed in thread cutting including finishing.

It is explanatory drawing of the conventional threading process, (A) shows the state which looked at the workpiece | work from the side, (B) respectively looked at the workpiece | work from the axial direction. It is explanatory drawing of the thread cutting process of 1 pass before finishing, (A) shows the state which looked at the workpiece | work from the side, and (B) respectively looked at the workpiece | work from the axial direction. It is explanatory drawing of NC lathe which implements a thread cutting process, (A) shows the case where the process of FIG. 2 is performed, (B) shows the case where the process of FIG. 5 is each performed. It is explanatory drawing of finishing, (A) shows the state which looked at the workpiece | work from the side, (B) respectively looked at the workpiece | work from the axial direction. It is explanatory drawing which shows the example of a change of arrangement | positioning of a blade tool from the axial direction of a workpiece | work.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 is an example of the case where the turning method of Patent Document 1 mentioned above is implemented by threading, and the two cutting tools are offset by a predetermined angle φ relative to the opposed 180 ° balance arrangement. The state of threading is shown. W is a workpiece, 10 is a first cutting tool, 20 is a second cutting tool, 11 is a processing surface before one pass by the first cutting tool 10, and 21 is a processing of the first cutting tool 10 before ½ rotation by the second cutting tool 20. Surfaces 23 and 23 indicated by hatching are removal portions by processing. Arrow A is the direction of rotation of the workpiece.
In general, in the threading process, the machining surface before one pass has a regeneration effect, but in the machining of FIG. 1, not only the machining surface 11 before one pass that the first cutting tool 10 processes but also the second cutting tool 20 processes. The processed surface 21 of the first cutting tool 10 before ½ rotation also has a regeneration effect. Here, even if the pitch angles θ1 and θ2 are set as described in Patent Document 1 and the reproduction effect is canceled, the undulation on the processed surface before one pass cannot be reduced, so chatter vibration is effectively suppressed. Can not do it.

On the other hand, in the present invention, as shown in FIG. 2, it is the same that the two cutting tools 10 and 20 are offset by a predetermined angle α that is an acute angle with respect to the 180 ° arrangement before one pass of the finishing process. However, the first cutting tool 10 has a one-blade cutting that cuts only one ridge line into the workpiece W among the two ridge lines of the cutting edge. The difference is that different flanks (thread slopes) are machined by cutting with the reverse single-edged blade that cuts only the opposite ridge line into the workpiece W.
Here, the appropriate offset angle α is a value in the vicinity of α ′ obtained by the following equation (1). In addition, the chatter vibration frequency used by Formula (1) can be measured during a process with a vibration sensor, a microphone, etc.

FIG. 3A shows an example of a machine tool that performs the machining shown in FIG. Here, an NC lathe 50 is shown as an example, and a main spindle 54 on a bed 51 is provided with a main spindle 54 that is rotationally driven by a motor 53, and rotates by gripping a workpiece W by a chuck 55 provided at an end. Thus, turning can be performed by the tool provided on the first tool post 56 and the second tool post 57. 58 is a claw of the chuck 55 and 59 is an encoder for detecting rotation of the main shaft 54.
In this NC lathe 50, the first tool 10 is attached to the first tool post 56 and moved above the work W, the second tool 20 is attached to the second tool post 57 and moved below the work W, and the work W is moved. While rotating at a predetermined rotational speed, the blades are cut in the radial direction as shown in FIG. 2 and sent in the direction of the rotation axis to perform different flank processing by the single blade cutting and the reverse single blade cutting, respectively, The path of escaping in the radial direction is defined as one cycle, and threading is performed by repeating this multiple times. However, the first cutting tool 10 and the second cutting tool 20 may be cut from the left and right instead of from the top and the bottom of the workpiece W to be threaded.

  Next, finishing is performed. FIG. 4 shows how a single cutting tool 30 is used for threading with a right angle cut. Here, as shown in FIG. 2A, the cutting tool 30 simultaneously cuts the processing surface 12 of the first cutting tool 10 before one pass and the processing surface 22 of the second cutting tool 20 before one pass. By arranging the cutting tool 30 on the basis of the expression (1) one pass before, the undulations of the machining surfaces 12 and 22 of the first cutting tool 10 and the second cutting tool 20 are in opposite phases as shown in FIG. In order to cancel, in the final pass of finishing, processing can be performed without causing regenerative chatter vibration. The cutting tool 30 may be either the first cutting tool 10 or the second cutting tool 20.

  As described above, according to the thread cutting method and the NC lathe 50 of the above embodiment, in the processing one pass before the finishing process, the two cutting tools 10 and 20 are used. In the second cutting tool 20, different flank machining is simultaneously performed by reverse single-blade cutting, and in finishing processing, machining is performed with a right angle cutting using one cutting tool 30. It is possible to cancel the regeneration effect of the single-blade cut before one pass and the regeneration effect of the reverse single-blade cut. Therefore, chatter vibration can be effectively suppressed in thread cutting including finishing.

In the above embodiment, the case where the two cutting tools 10 and 20 are offset by a slight angle with respect to the 180 ° arrangement has been described. However, as shown in FIG. Even when the angle is offset by the angle, it can be implemented. As shown in FIG. 3B, the NC lathe 50 in this case includes a first tool post 56 to which the first tool 10 is attached and a second tool post 57 to which the second tool 20 is attached, respectively. It cuts from the top downward, performs a single blade cut and a reverse single blade cut to perform threading. However, the first cutting tool 10 and the second cutting tool 20 may be cut from below the workpiece W, or may be cut from the side of the workpiece W.
In the case of FIG. 5, the appropriate offset angle β is a value near the value β ′ obtained by the following equation (2).

  On the other hand, the machine tool is not limited to an NC lathe, and may be a multi-tasking machine, a machining center, or the like as long as the above threading method can be executed. In addition, the machining before finishing is not limited to machining two different flank using two cutting tools from before a plurality of passes, but different flank using two cutting tools only in the machining one pass before finishing. It may be processed.

  10. ・ 1st cutting tool, 12. ・ Processing surface before one pass by the first cutting tool, 20. ・ Second cutting tool, 22. ・ Processing surface before one pass by the second cutting tool, 30. ・ Cutting tool, 23. ・Remover, 50 ·· NC lathe, 52 ·· Spindle base, 54 ·· Spindle, 55 ·· Chuck, 56 ·· First turret, 57 ·· Second turret, W ·· Workpiece, α, β · -Offset angle.

Claims (4)

Cutting the cutting tool in the radial direction while rotating the workpiece at a predetermined rotational speed, processing the threaded portion by sending it in the rotational axis direction, and then passing the cutting tool in the radial direction multiple times as one cycle. It is a method of threading by repeating,
In the processing at least one pass before the finishing process, two knives are used, and one of the knives is simultaneously subjected to flank machining by one-blade cutting and the other knives by reverse single-blade cutting.
In the finishing process, a threading method is performed by performing a right-angle cutting process using one of the cutting tools.   The two cutting tools used in the processing before the finishing processing are arranged such that one of them is shifted by a predetermined angle that is an acute angle around the rotation center axis with respect to the arrangement that is 180 ° around the rotation center axis of the workpiece. The threading method according to claim 1, wherein:   The two cutting tools used in the processing before the finishing processing are arranged such that one of them is shifted by a predetermined angle that is an acute angle around the rotation center axis with respect to the arrangement that becomes 0 ° around the rotation center axis of the workpiece. The threading method according to claim 1, wherein: A path in which a cutting tool is cut in the radial direction with respect to the work while rotating the work at a predetermined rotation angle, and the cutting tool is processed by feeding it in the rotation axis direction, and then the cutting tool is released in the radial direction. Is a machine tool that can perform threading by repeating multiple times as one cycle,
A machine tool capable of executing the threading method according to any one of claims 1 to 3.

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