JP2019072810A - Finish processing method - Google Patents

Abstract

To provide a method for finish-processing a work-piece that can obtain an excellent processed surface by controlling circumferential velocity of a rotation tool and a work-piece and controlling a cutting position, without additionally installing equipment, even in processing using a machining center.SOLUTION: By using a machining center which is equipped with one rotation shaft that rotates a rotary table on which three orthogonal shafts and a work-piece are placed, a rotation tool that cuts the work-piece while rotating and a numerical control device for numerically controlling the three orthogonal shafts, where circumferential velocity α of the rotation tool and circumferential velocity β of the work-piece satisfy a formula of α>β, finish-processing the work-piece is performed while pressing one of the work-piece and the round insert against the other, at an angle γ formed by a cutting point of the round insert including a center shaft of the work-piece and a horizontal shaft orthogonal to the center shaft of the work-piece.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of finishing a work by using a machining center to process a work (hereinafter referred to as a work) rotating about an axis with a rotary tool rotating about an axis.

  Nowadays, while processing by multi-tasking machines (including 5-axis machines) is widespread, rough machining and finishing processes of workpieces are done by turning as a general workpiece processing process using a lathe etc. After that, the machining center or the like is changed in stages, and a cutting process is performed by the machining center or the like. Thus, in processing one work, a setup change was unavoidable.

  In such processing steps, the rotary table mounted on a machining center etc. is used to continuously rotate the attached workpiece at a rotational speed that can withstand the cutting force, and index the attached workpiece at an arbitrary angle. It has been used for applications such as holding fixed.

  On the other hand, if the rotary table invented by the present applicant described in Patent Document 1 is used for a machining center, the workpiece can be rotated at a high speed like a lathe, so the roughing process with a conventional lathe and cutting with a machining center Even if it is possible to consolidate and do not purchase expensive complex processing machines and lathes, it is possible to process only with the existing machining center without performing setup replacement.

JP, 2015-174187, A

  However, with the rotary table of Patent Document 1, although the processing accuracy equivalent to roughing with a lathe can be realized, a good processing surface equivalent to finish processing can not be obtained.

  In general, the tool of the machining center uses an end mill, and when processing a work with this end mill, it will cut intermittently when seen from the work due to the configuration of the cutting edge, and the machined surface will be scaly It becomes the finish of the shape. Therefore, it is impossible to make a mirror-like finish like finish processing.

Therefore, if a rotary tool known in the art is used, it is possible to cut continuously when viewed from a work, so that it is possible to obtain a better machined surface than roughing.
However, although it is possible to obtain a better machined surface than roughing with a rotary tool, it is not possible to obtain a machined surface with high precision such as finishing depending on the processing conditions.

  Therefore, it is an object of the present invention to control the peripheral speeds of a rotary tool and a work and to control the cutting position without adding equipment even when machining with a machining center, and to obtain a good processing surface by controlling the cutting position. It is to provide a finishing method.

  In order to solve the above-mentioned problems, in the method for finishing a workpiece according to the present invention, three orthogonal axes and one rotation axis for rotating a rotating table on which the workpiece is mounted, a rotating tool for cutting a workpiece while rotating, and orthogonal axes Using a machining center equipped with a numerical controller that drives and controls three axes, the relationship between the peripheral tool speed α and the workpiece peripheral speed β is α> β, including the workpiece center axis and the cutting point of the round piece insert It is characterized in that an angle γ formed by a horizontal axis orthogonal to the workpiece central axis is provided, and one of the workpiece and the round insert is pressed while pressing against the other.

  According to the above-described procedure, the turning process can be performed only with the machining center and the rotary table mounted on the machining center, and excellent machining accuracy can be obtained. In addition, it is not necessary to perform setup replacement to another machine, and the cost due to the installation of additional equipment can be reduced.

  Further, in the finish machining method of a work of the present invention, it is preferable to control the rotation direction of the rotary tool so as to be up-cut in accordance with the movement directions of three orthogonal axes. According to the above procedure, the processing accuracy can be further improved. Further, although the details will be described later, since resistance is added from the thin part to the thick part of the chips, it is possible to cut more smoothly.

  Further, in the method of finishing and processing a work according to the present invention, it is preferable that one rotation axis is disposed such that the axis line is perpendicular to the axis line of the rotating tool. According to the above procedure, there is no need to incline the rotary tool with respect to the axis, and the work does not have to incline with respect to the axis either, so the machine configuration itself becomes a simple configuration and also in processing An accurate machining surface can be obtained without performing a complicated machining program.

  Moreover, in the finish processing method of the work of the present invention, it is preferable to carry out by dry type which does not use cutting oil. According to the above procedure, since the cooling with the cutting oil is not performed, it is possible to reduce the strength of the work by increasing the amount of heat generation due to friction. As a result, cutting resistance is reduced, so that processing can be performed on the rotary table with less load. Therefore, stable processing is possible, and a highly accurate processing surface can be obtained.

  Further, in the finishing method of a work of the present invention, it is preferable that the angle γ be determined in accordance with the deflection amount of the rotary tool at the time of processing. According to the above procedure, it is possible to obtain a machined surface with high accuracy.

  Furthermore, in the method for finishing a workpiece according to the present invention, the deflection amount is equal to the component force (hereinafter referred to as component a) that causes the rotary tool corresponding to the cutting resistance to work and the rotary tool corresponding to the reaction force by the cutting. It is preferable that the component force (hereinafter, referred to as component b) be determined to be balanced. According to the above procedure, it is possible to obtain a machined surface with high accuracy.

  According to the method of finishing a workpiece according to the present invention, the peripheral speed of the rotating tool and the workpiece is controlled and the cutting position is controlled without adding equipment even in machining with a machining center, and a good machining surface can be obtained. Can.

It is a model perspective view for explaining the finishing method of the work by one embodiment of the present invention. It is an enlarged view of a rotary tool, (a) is a front view, (b) shows a bottom view, respectively. It is a front view in the cutting position of a round piece insert and a work. It is the graph which showed the relationship between a round piece insert and cutting resistance. It is the graph which showed the relationship between a round piece insert and a cutting amount error. It is the graph which showed the relationship between a round piece insert and surface roughness.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings. However, the present invention is not limited to the following embodiments. Moreover, changes can be made as appropriate without departing from the scope in which the effects of the present invention are exhibited. Incidentally, in FIGS. 1 to 4 described later, the x-axis, the y-axis and the z-axis are shown. The orientations of the x-axis, y-axis and z-axis are identical to one another, even in different views. In the description of this specification, for convenience, the x-axis positive side is “right”, the x-axis negative side is “left”, the y-axis positive side is “front”, and the y-axis negative side is “rear”. The z-axis direction positive side is the "upper" side, and the z-axis direction negative side is the "lower" side.

FIG. 1 is a schematic perspective view for explaining a finishing method of a work according to an embodiment of the present invention.
As shown in FIG. 1, the basic configuration of the machining center 100 is a combination of the table 10 and the tool spindle 20 and has three orthogonal axes, and a numerical control device 40 that controls their movement, the rotation of the tool spindle 20 and the like. And so on.
The configuration will be described below while showing an example of orthogonal three axes.

The tool spindle 20 can move one-dimensionally in the vertical direction (z-axis direction) with respect to the table table 10, and around the axis A at a constant rotational speed β, in the arrow a1 direction or a2 direction It is rotatable.
A rotary tool 23 consisting of a shank 21 and a round piece insert 22 is attached to the tip of the tool spindle 20. The shank 21 has a cylindrical shape and is integrally integrated with the tool spindle 20. In addition, the axis A of the tool spindle 20 and the axis of the shank 21 are mounted so as to coincide with each other.

  Similarly, the round piece insert 22 is attached to the tip of the shank portion 21 so as to be integrally rotatable, and so that the axis A and the axis of the round piece insert 22 coincide with each other.

(Round piece insert)
The round piece insert 22 has a circular shape when viewed in a cross section orthogonal to the axis A as shown in FIG. 2, and the intersection of the tip end face 22a and the side face 22b is a cutting edge 22c.

The table base 10 is movable in two dimensions in the front-rear direction (y-axis direction) and the left-right direction (x-axis direction) with respect to the tool spindle 20.
On the table table 10, a rotary table 30, which is one rotation axis, is mounted so as to be movable integrally with the table table 10.
The mounting of the rotary table 30 is preferably arranged so that the axis B of the rotary table 30 and the axis A of the rotary tool 23 are perpendicular.

The numerical control device 40 mainly controls the moving directions of orthogonal three axes constituted by the tool spindle 20 and the table table 10, and controls the rotational direction and rotational speed of the tool spindle 20.
The end face of the work is cut by controlling the rotation direction of the round insert 22 so as to be the upcut described later according to the movement directions of the orthogonal three axes by the numerical control device 40. This makes it possible to obtain a good processed surface.

(Rotary table)
A chuck (not shown) is fixed to the rotary table 30, and the workpiece w is held by driving the chuck (not shown).
A servomotor (not shown) is mounted inside, thereby making it possible to rotationally drive the work.

Further, a control device 50 is connected to control the rotational speed and the rotational direction.
In other words, by driving the rotary table 30 by the control device 50, the work w can be rotated around the axis B of the rotary table 30 in the arrow b1 direction or the b2 direction at a constant rotation speed α.

Example 1
The inventors of the present invention evaluated the relationship between the cutting resistance to the round insert, the infeed amount error, and the surface roughness, using the processing apparatus, the processing procedure, the processing position, and the processing conditions.

Processing device
The processing apparatus mounted the circular table developed by the present applicant on the table table using a commercially available 3-axis machining center (VERTICAL CENTER NEXUS 430B-2 HS manufactured by Yamazaki Mazak Co., Ltd.).
The main spindle of the machining center is rotatable to 18000 min ^-1 , the table size is 1100 mm in the x-axis direction and 430 mm in the y-axis direction, and a round piece insert is attached to the main spindle.
The circular table used was capable of rotating up to 1000 min ⁻¹ .

<Processing procedure>
The processing operation in the first embodiment will be described with reference to FIG.
First, the round piece insert 22 is moved along the z-axis to a predetermined processing position, and is held immovably at that position. Next, the table base 10 is moved relative to the round piece insert 22 to the processing position along the x, y axes. In this state, the circular table 30 is rotated at a predetermined rotational speed so as to have a constant speed, and the work w is rotated about the axis B in the direction of the arrow b1.

Then, the tool spindle 20 of the machining center 100 is rotated at a predetermined rotation speed so as to be a constant speed, and the round piece insert 22 is rotated about the axis A in the direction of the arrow a2.
At this time, the workpiece w and the round piece insert 22 may be rotated simultaneously or may be moved while rotating to a predetermined processing position.

  In this state, by moving the table base 10 to the left along the x axis, cutting is performed while pressing one of the work w and the round piece insert 22 against the other.

  For convenience, when the table base 10 moves to the left as described above, the round piece insert 22 rotates in the direction of the arrow a2 around the axis A, so that the blade of the round piece insert 22 abuts against the cut portion and is cut up While processing is defined as up-cut.

On the other hand, cutting by moving the table base 10 to the left side and rotating the round piece insert 22 around the axis A in the direction of the arrow a1 is defined as down-cut.
The relationship between the peripheral speed α of the round insert 22 and the peripheral speed β of the work w is set as α> β.

Processing position
The processing position in the first embodiment will be described with reference to FIG. FIG. 3 shows a front view of the round piece insert 22 and the cutting position of the work w.

  As shown in FIG. 3, a cutting resistance M by processing acts on the rotary tool 23 (the round piece insert 22 and the shank portion 21), and a component force m causing the rotary tool 23 to occur is generated. In addition, when the round piece insert 22 is cut into the work w, a reaction force N is generated due to the cutting, and a component force n causing the rotary tool 23 to fall is generated.

The offset angle γ is appropriately determined so that the force between the component force m and the component force n is balanced.
Then, a position at which an offset angle γ is provided from a horizontal axis that includes the workpiece central axis and is orthogonal to the workpiece central axis is defined as a cutting position.

By this offset angle γ, deflection of the rotary tool 23 can be minimized, and a machined surface with high accuracy can be obtained.
The offset angle γ is appropriately determined in accordance with the processing conditions because an appropriate value changes depending on the rigidity of the rotary tool 23, the cut amount of the round piece insert 22, the work material, and the like.

<Processing conditions>
The processing conditions in Example 1 are shown in Table 1 below.

As shown in Table 1, the main processing conditions are as follows: processing method, round piece insert diameter, workpiece material, work peripheral speed β, feed amount per one work rotation, infeed amount, round piece insert rotation speed, round piece insert peripheral speed Among the nine items of α and offset angle γ, six items were fixed, and the round piece insert rotational speed (round piece insert circumferential speed α) and the offset angle γ were changed and the verification was performed. Then, the cutting resistance, the cutting depth error, and the surface roughness were measured when the number of round insert rotations (min ⁻¹ ) was 750, 1500, 3000 and 4500, respectively.

Further, under the processing conditions, at first, the workpiece diameter φ130 is used, and the rotational speed of the circular table is calculated so that the workpiece circumferential velocity is 150 (m / min) relative to the workpiece diameter. The rotation speed of the circular table at that time was about 367 (min ⁻¹ ). And in the next verification, I used one work all the time. That is, although the diameter is reduced depending on the cutting amount, the reduced workpiece diameter at the time of the next verification is measured each time, and the rotational speed is calculated and verified so that the workpiece peripheral speed is 150 (m / min) doing.
Moreover, the processing environment at the time of processing was performed by the dry type which does not use cutting oil.

  4 to 6 show the relationship between the cutting resistance to the round piece insert, the infeed amount error, and the surface roughness, respectively.

<Relation to cutting resistance>
FIG. 4 is a graph showing the relationship between the round insert and the cutting resistance.
From FIG. 4, no. As for Nos. 1 to 4, when the number of revolutions of the round insert is greater than 3000 (min ⁻¹ ), the cutting resistance is low.
As a reason, at the cutting point between the round piece insert and the work, it is considered that heat is generated by friction, the strength of the work is reduced, and the cutting resistance is reduced.
Here, the relationship between the round piece insert rotational speed, the round piece insert circumferential speed, and the work circumferential speed is shown in Table 2 below.

From Table 2, when the round piece insert rotational speed is 3000 (min ⁻¹ ) or more, the round piece insert circumferential speed is higher than the work circumferential speed 150 (m / min).
That is, it can be said that the cutting resistance is low when the relation between the round piece insert circumferential speed α and the work circumferential speed β is α> β.

<Relationship with infeed amount error>
FIG. 5 is a graph showing the relationship between the round piece insert and the depth error.
The round piece insert is arranged and processed so as to obtain the set amount of infeed e (0.2 mm in the first embodiment) which is set on the basis of the outer periphery of the work as the infeed amount error g mentioned here. Later, the diameter of the workpiece is measured to calculate the actual depth of cut f, and the difference value is said.

That is, the depth error g is defined as follows.
Depth of cut error g = Actual depth of cut f-Set depth of cut e

When considered, No. In 1, the component force n of the reaction force N generated by the cut shown in FIG. 3 exceeds the component force m of the cutting force M, and the cut is insufficient.
No. In No. 3 and 4, No. The opposite is to 1 and the force m exceeds the force n, and the amount of cutting increases.
No. In 2, the force m and the force n are balanced. Therefore, the depth of cut error is extremely small.

  Thus, in the first embodiment, No. 1 It can be seen that the offset angle γ of 5 ° is a condition under which a good accuracy can be obtained.

<Relation with surface roughness>
FIG. 6 is a graph showing the relationship between the round insert and the surface roughness.
As shown in FIG. 6, No. a round insert insert rotational speed is greater than 3000 min ^-1 The surface roughness of 2 is improved.

  The reason is that the cutting resistance is lowered by making the round piece insert circumferential speed larger than the workpiece circumferential speed, and the deflection angle of the tool is reduced by appropriately setting the offset angle γ (here 5 °) It is considered that the surface roughness was improved by

  From the above verification results, according to the relationship between the round piece insert and the cutting resistance, when the circumferential speed of the round piece insert exceeds the circumferential speed of the work, the cutting resistance decreases and the load on the circular table can be reduced. I understood.

  Then, according to the relationship between the round piece insert and the infeed amount error, the accuracy of the infeed amount can be improved by setting the offset angle γ so as to obtain an appropriate deflection amount (balance between the component force m and the component force n). I knew I could do it.

  Furthermore, according to the relationship between the round piece insert and the surface roughness, the circumferential speed of the round piece insert is higher than the circumferential speed of the work, and an appropriate deflection amount (balance between the force m and the force n) is obtained. It has been found that if the offset angle γ is set to 0, it is possible to obtain a machined surface with an accurate finish machining level.

  That is, even when processing is performed by a machining center, peripheral speeds of the rotary tool and the work can be controlled and a cutting position can be controlled without adding equipment, and a good processing surface can be obtained. In other words, the turning process can be performed only with the machining center and the rotary table mounted on the machining center, and good machining accuracy at the finishing process level can be obtained. In addition, it is not necessary to perform setup replacement to another machine, and the cost due to the installation of additional equipment can be reduced.

  Also, by using up-cut, resistance is gradually added to the round piece insert from thin chip area to thick chip area, smooth cutting is possible, and cutting is still performed on thin chip area after processing Because the heat generation temperature of the round piece insert due to cutting is small and the heat generation temperature of the round piece insert increases as the chips get thicker, heat generation due to cutting is easily carried away by the chips and stabilized. It can be processed.

  In addition, there is no need to incline the rotary tool with respect to the axis, and there is no need to incline the work with respect to the axis either, so the machine configuration itself becomes a simple configuration and complex processing also in processing An accurate machining surface can be obtained without programming.

  Further, since the cooling with the cutting oil is not performed, it is possible to reduce the strength of the work by increasing the amount of heat generation due to the friction. As a result, cutting resistance is reduced, so that processing can be performed on the rotary table with less load. Therefore, stable processing is possible, and a highly accurate processing surface can be obtained. Further, since coolant water, coolant tank, coolant pump, coolant hose, nozzle, solenoid valve, etc. are not required, the cost can be reduced accordingly.

  Although the present invention has been described above by the preferred embodiments, such description is not a limitation and, of course, various modifications are possible. Although the relative movement of the work relative to the rotary tool has been described in the above embodiment, the present invention is not limited thereto. The work may move in the x-axis direction, and the rotary tool may move in the y and z axes. It is possible to move in the direction, and the rotary tool may move in the x and z axes, but is not limited thereto.

  Although the machining center has been described as vertical (the tool spindle is in the vertical direction), the present invention is not limited to this, and horizontal or gate may be used. In the case of a horizontal machining center, the circular table is placed horizontally (rotation axis is parallel to z axis It is better if you use

  Moreover, although the orthogonal 3 axes are controlled by the numerical control device of the machining center and the 1 rotation axis is controlled by the control device of the circular table, the invention is not limited to this, the rotational control of the circular table is controlled by the numerical control device of the machining center It does not matter.

  Moreover, although measurement was performed on the processing conditions of Table 1, it changes suitably with not only this but workpiece | work material and workpiece | work diameter.

  The processing environment is not limited to the dry type, and may be a wet type using cutting water, or a semi-wet type between dry type and wet type.

  The work is not limited to a cylinder, but may be a cylinder or a prism, and the shape of the work is not limited.

  Furthermore, the servomotor mounted on the circular table is not limited to this, and may be a DD motor or the like.

DESCRIPTION OF SYMBOLS 10 Table stand 20 Tool spindle 21 Shank part 22 Round piece insert 23 Rotary tool 30 Circular table 40 Numerical control device 50 Control device 100 Machining center alpha, beta Peripheral velocity gamma angle A, B axis line a1, a2, b1, b2 Direction of rotation m, n components w work

Claims (6)

3 axes of orthogonal rotation and 1 axis of rotation to rotate the table on which the work is placed,
A rotating tool that cuts the workpiece while rotating,
Using a machining center provided with a numerical control device for driving and controlling the three orthogonal axes,
The relationship between the peripheral velocity α of the rotating tool and the peripheral velocity β of the workpiece is α> β,
Providing an angle γ between the cutting axis of the rotary tool including the workpiece central axis and a horizontal axis orthogonal to the workpiece central axis,
A method of finishing a work, comprising cutting while pressing one of a work and a rotary tool against the other. In the method for finishing a work according to claim 1,
A method of finishing a workpiece, comprising controlling a rotation direction of the rotary tool to be up-cut according to the movement directions of the three orthogonal axes. In the finishing method of a work according to claim 1 or 2,
The method according to any one of the preceding claims, wherein the first axis of rotation is arranged such that the axis is perpendicular to the axis of the rotating tool. In the finishing method of a work according to any one of claims 1 to 3,
A method for finishing a workpiece, characterized in that it is performed dry without using cutting oil. In the work finishing method according to any one of claims 1 to 4,
A method of finishing a workpiece, wherein the angle γ is determined according to the amount of deflection of the rotary tool at the time of processing. In the work finishing method according to claim 5,
The component force (hereinafter referred to as a component force m) in which the deflection amount causes the rotary tool corresponding to the cutting resistance and the component force (hereinafter referred to as a component force n) cause the rotary tool corresponding to the reaction force by the cutting A method of finishing a workpiece characterized in that it is determined to be balanced.

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