JP2635083B2 - Lathe and lathe processing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lathe for performing machining by moving a tool with respect to a workpiece and a machining method using the lathe.

[Conventional technology]

In general, in a conventional lathe, a rotating workpiece is brought into contact with the cutting edge of the tool while the tool is fixed to a tool base, and the tool is further moved in the direction of the rotation axis of the workpiece. Processing is performed by moving. That is, for the cutting edge of the tool, during machining,
The same part is always in contact with the workpiece.

[Problems to be solved by the invention]

In machining with a lathe, the wear of the tool edge is remarkable, especially when machining is always performed on the same part of the tool edge as in the conventional lathe, since the amount of wear increases in proportion to time,
Tool life is very short. In particular, when processing a workpiece having a high hardness (for example, a rolling roll), the wear rate is high, and the processing accuracy deteriorates due to such wear of the tool. Further, even if the tool is replaced during the cutting, a joint error occurs in the workpiece at the replaced portion, so that deterioration of the machining accuracy is inevitable.

Therefore, conventionally, when processing the workpiece, a lathe is used only in the roughing stage, and grinding is performed with a grinding tool such as a grindstone in the finishing stage. However, in this case, since both a cutting machine and a grinding machine must be prepared, a large facility cost is required, and there is a disadvantage that the cost is increased.

Furthermore, in the above-mentioned grinding, a large depth of cut cannot be obtained at a time as compared with the machining performed by a lathe, so that the machining must be performed while repeating the reciprocating movement of the tool many times, resulting in a long process time. Required. In addition, it is necessary to change the grindstone sequentially according to the required finish surface roughness and the material of the workpiece, and since such a grinding tool is relatively heavy and inconvenient to handle,
Poor processing efficiency. In addition, a large amount of grinding fluid is required, and cleaning and processing of the grindstone powder are also troublesome, so that facility management is difficult.

Further, in the case of machining by the above-mentioned lathe, when a workpiece is not machined into a perfect cylindrical shape, but a machining that changes its radius in the axial direction, for example, a crown machining that slightly expands a central portion is required. However, in order to perform such machining, not only is the tool moved in a direction parallel to the axial direction of the workpiece, but also at the same time, the tool and the workpiece are minutely moved in the radial direction of the workpiece. Extremely complicated transfer control such as moving by an amount is required, and it is very difficult to perform the crown processing at low cost.

In view of such circumstances, the present invention can improve machining efficiency and machining accuracy by reducing the amount of tool wear caused by turning, and can easily process a workpiece without complicated control. An object of the present invention is to provide a lathe capable of crowning an object and a processing method using the lathe.

[Means for solving the problem]

The present invention provides a tool base for rotatably supporting a tool, a workpiece supporting / rotating means for supporting and rotating a workpiece, and relatively moving the tool base in a direction of a rotation radius and a rotation axis of the workpiece. In a lathe provided with a feeding means for causing the tool to have an arc shape, the tool is mounted on the tool base at a position where the center of curvature of the tool edge is slightly shifted to a side farther from the workpiece than the center of rotation of the tool. Tool rotation driving means for rotating a tool in the tool table, and moving the tool table in the direction of the rotation axis with respect to the workpiece so as to process the workpiece into a shape in which the center portion expands. Control means for rotating the tool.

Here, "slightly deviate" means that the workpiece is deviated to such an extent that the central portion of the workpiece expands so that crown processing can be performed.

The present invention also relates to a machining method using a lathe, wherein the workpiece is rotated, and a tool having an arc-shaped cutting edge is centered on a point that is slightly eccentric to a side closer to the workpiece than the center of curvature of the cutting edge shape. The workpiece is made to move in the direction of the rotation axis while the relative position of the workpiece in the rotational radius direction is fixed while being rotated, thereby processing the workpiece into a shape in which the center portion is expanded.

(Operation)

According to the above configuration, since the portion of the cutting edge that comes into contact with the workpiece changes when the tool rotates during machining, the tool life is longer compared to a structure in which the same portion of the cutting edge always contacts the workpiece. Is greatly extended. Furthermore, by making the entire area of the tool edge abut against the workpiece while the tool table performs the feed movement over the entire area of the workpiece, the tool edge can be used evenly over the entire area. And uneven wear can be prevented.

In addition, while rotating the tool about a point eccentric to the side closer to the workpiece with respect to the center of curvature of the cutting edge shape, the tool is rotated while the relative position in the rotation radial direction with respect to the workpiece is fixed. Since the workpiece is machined into a shape in which the center portion expands by moving the workpiece relatively in the axial direction (that is, crown machining), complicated control such as moving the tool in the radial direction of the workpiece during machining is performed. The above-mentioned crown processing can be performed without performing.

〔Example〕

FIG. 1 is a diagram showing the overall configuration of a lathe according to an embodiment of the present invention. This lathe includes a headstock 2 and a tailstock 3 that support both ends of a substantially cylindrical workpiece (workpiece) 1. The headstock 2 is for rotating the workpiece 1 at high speed. Built-in main motor.
On the side of the workpiece 1 in this supported state,
A carriage 4 configured to be movable in the rotation axis direction of the work piece 1 is provided, and a tool table 6 that supports a cutting tool 5 is provided on the carriage 4.

The structures of the carriage 4 and the tool table 6 are shown in FIGS.
Description will be made based on the drawings. As shown in FIG. 2, two ball screw nuts 7 are fixed to the lower part of the carriage 4 in a line in series, and the ball screw nut 7 is a ball rotatably supported on the lathe body side. It is screwed to the screw 8. The ball screw 8 is connected via a reduction gear box 9 to a vertical feed drive motor 10 installed on the lathe main body. The ball screw 8 is driven to rotate by the vertical feed drive motor 10. , Ball screw nut 7 meshing with this
The carriage 4 is reciprocally driven (vertically fed) in the above-described direction.

A cross slide 11 as shown in FIG. 3 is fixed to a lower portion of the tool base 6 so that the cross slide 11 is guided in a horizontal direction in which the cross slide 11 comes into contact with or separates from the workpiece 1. Is mounted on the carriage 4. A ball screw nut 13 similar to the ball screw nut 7 is provided inside the cross slide 11, and a ball screw 12 screwed to the ball screw nut 13 is horizontally supported in the carriage 4. In this state, it is connected to a transverse drive motor (feed means) 15 via a reduction gear box 14. When the ball screw 12 is rotationally driven by the lateral feed driving motor 15, the tool base 6 is driven (laterally fed) in the above direction integrally with the ball screw nut 13 meshing with the ball screw 12. Comes into contact with and separates from the work piece 1. In FIG. 6, reference numeral 33 denotes a limit switch for detecting the displacement of the tool stand 6 in the lateral feed direction.

As shown in FIGS. 4 to 7, the turning table 17 is supported on the main body of the tool table 6 via a bearing 35.
The swivel table 17 is centered on the swivel axis 16 and
The cutting tool 5 is mounted on the upper surface of the turntable 17.

The cutting tool 5 is provided with through holes 5a and 5b at two locations. Bolts 18 are loosely inserted into the through holes 5a and 5b, and the bolt 18 is The cutting tool 5 is locked on the revolving base 17 in a state in which the cutting tool 5 can be slightly moved in the direction of coming and going with respect to the workpiece 1 by being screwed and fixed to the upper surface of the work piece 1. Further, a tool centering device comprising an adjustment bolt 19 fixed to the cutting tool 5, two nuts 20 screwed to the adjustment bolt 19, and a support member 21 for supporting the adjustment bolt 19 is provided on the swivel table 17. 22 is provided, and the relative position of the cutting tool 5 with respect to the swivel table 17 can be adjusted by appropriately rotating the adjustment bolt 19.

As shown in FIG. 7, the cutting tool 5 has an arc-shaped cutting edge having a radius of curvature r, and is eccentric to a side slightly closer to the workpiece 1 than the center of curvature of the cutting edge as described later. The mounting position is adjusted by the tool centering device 22 so that the cutting tool 5 rotates about a point.

Below the swivel 17, as shown in FIG.
Two gears 23, 24 are arranged side by side in the vertical direction. Gear 23
Is fixed to the peripheral surface of the turning shaft 16 via a key 25, and the gear 24 is directly fixed to the lower surface of the turning shaft 16 in a state of being fitted to the outer peripheral surface of the gear 23.

On the other hand, a ball screw 26 is rotatably supported on the main body of the tool rest 6, and two ball screw nuts 27 meshing with the ball screw 26 are provided in series. Racks 28 and 29 meshing with the rack 24 are fixed. The ball screw 26 is connected via a shaft coupling device 31 to a turning drive motor (tool rotation drive means) 30 fixed to the side of the tool base 6.

The rotation of the ball screw 26 by the turning drive motor 30 causes the ball screw nut 27 meshing with the ball screw nut 27 and the two racks 28 and 29 to translate and move by the movement of the racks 28 and 29. The gears 23, 24, the turning shaft 16, and the turning table 17 that mesh with each other are driven to turn integrally, whereby the cutting tool 5 turns with respect to the workpiece 1. In the figure, 35
Are limit switches for detecting both limit positions of the turn of the turntable 17.

Further, as shown in FIG. 1, an operation panel 3 for inputting a predetermined machining command is provided on the lathe in this embodiment.
6, and a control panel 37 equipped with a computer are provided. The control panel 37 includes a rotation detector 38 for the workpiece 1 provided on the headstock 2,
Signals from the limit switches 3 and 34 and the operation unit 36 are input, and a control panel 37 that receives these signals outputs a control signal to each motor.

Next, a method of processing the workpiece 1 by the lathe will be described with reference to the flowchart of FIG.

First, when performing machining, the cutting conditions are set (step S ₁ ). The cutting conditions referred to here include the material of the cutting tool 5, the radius of curvature r of the cutting edge thereof, the cutting speed (the relative speed between the workpiece 1 and the cutting tool 5) v, the feed speed (the amount of longitudinal feed per work rotation) f. And the turning angular velocity β of the cutting tool 5.

The radius of curvature r of the cutting edge and the feed speed f can be determined from the required surface roughness Rmax of the workpiece 1. That is, since it is known that these values have a relationship of Rmax = f ² / (8 · r)..., The curvature radius r and the feed speed f are calculated from the required surface roughness Rmax. Can be set. In this case, the feed rate f can be increased by setting the radius of curvature r of the cutting edge to be large, thereby increasing the speed of machining. However, if the radius of curvature r is increased, the cutting tool Since the turning radius must be set large, which leads to an increase in the size of the apparatus, it is desirable to set the radius of curvature of the cutting edge in consideration of the balance between the two.

As for the cutting speed v, the higher the cutting speed v, the higher the speed of machining can be achieved, but the shorter the tool life, the shorter the cutting speed v needs to be set in consideration of both. is there.

Further, the turning angular velocity of the cutting tool 5 (that is, the turning table 17)
Is set so that the entire area of the cutting edge is in contact with the workpiece 1 from the start of machining to the end thereof. That is, the central angle of the cutting edge arc is θ,
Assuming that the cutting time required for machining is t, the angular velocity β is set as β = θ / t. Note that this cutting time t is set to
Is obtained from the overall length L, the cutting speed v, and the feed speed f of the processing area. The above set values may be input to a program in the case of an NC lathe, and in other cases, the obtained values may be manually set using a speed adjustment dial or the like.

After setting the cutting conditions in this way, the work piece 1 is set between the headstock 2 and the tailstock 3 (step S ₂ ), and the cutting tool 5 is mounted on the swivel base 17 (step S ₂ ). S _3).

To mount the cutting tool 5, first, the cutting tool 5 is placed at a predetermined position on the swivel base 17, and bolts 18 are inserted into the through holes 5a and 5b to fix the same to the swivel base 17. An adjustment bolt 19 of the tool centering device 22 is fixed to the tail end, and the turning center is adjusted by rotating the bolt 19 and sliding the cutting tool 5.

Here, if the position of the cutting tool 5 is adjusted so that the center of curvature of the cutting edge shape of the cutting tool 5 matches the center of rotation thereof (point C in FIG. 7), the workpiece 1 becomes a complete cylindrical shape. It will be processed. On the other hand, by performing position adjustment such that the center of curvature is slightly farther from the workpiece 1 than the center of rotation, crown processing as described later can be performed. For this position adjustment, a measuring instrument such as a dial indicator is brought into contact with the tool edge, and the tool 5
The above condition can be satisfied by adjusting the position of the blade so that the cutting edge does not displace in the radial direction even if the blade is turned in any direction. If the standby position of the carriage 4 before processing is set near the tailstock 3, the ninth
As shown in the figure, by fixing the dial indicator 38 to the side surface of the tailstock 3, the centering of the cutting tool 5 can be performed at the standby position using the dial indicator 38. Will be reasonable.

Next, the cutting tool 5 is processed by the operation of the vertical feed drive motor 10 at the starting point (in FIG. 1, the right end of the workpiece).
(Step S ₄ ), and the swivel table 17 is moved to the origin position (in FIG. 1, the position where the swivel is most turned clockwise).
Is moved, it rotates the workpiece 1 by turning the main motor in this state at a predetermined rotational speed (rotational speed corresponding to the cutting speed v) (step S _5). Then, as shown by the two-dot chain line on the right side of FIG. 1, the tool tip is slightly brought into contact with the surface to be cut of the workpiece 1, and this position is set as the origin in the vertical feed direction and the horizontal feed direction (step).
S _6).

After setting the origin position in this way, the cutting tool 5 is slightly separated from the workpiece 1. And operation panel 36
In by receiving switch operation, while discharging the cooling means such as cutting oil or air, the cutting tool 5 is brought into contact again the workpiece 1 starts processing of the workpiece 1 (step S _7).

This processing is the carriage 4 at the same time as longitudinal feed by the feed rate f, and the swivel base 17 carried by pivoting in the angular beta (Step S _8). As a result, the workpiece 1 is constantly machined in a state where a new portion of the tool edge is in contact with the workpiece, and the entire area of the tool edge is moved while the carriage 4 moves from the machining start point to the end point. It comes into contact with the piece 1. When the cutting tool 5 is turned around the same point as the center of curvature of the tool edge, the cutting amount does not change. However, if the center of curvature is shifted to a side farther from the workpiece 1 than the center of rotation, Accordingly, the cut amount gradually decreases from the end of the workpiece 1 toward the center.

After the completion of cutting this way (in step S ₉
YES), the drive of the longitudinal feeding drive motor 10 and the horizontal feed drive motor 15 to return the cutting tool to the standby position before machining (Step S _10), after stopping the main motor (step S _11), the workpiece by removing the piece 1 from the lathe (step S _12), and terminates the entire processing step.

As described above, in the machining by the lathe, the cutting tool 5
Since turning is performed while turning, the following effects can be obtained as compared with a conventional lathe.

During machining, a new cutting edge is always supplied by turning the cutting tool 5, so that the cutting time is short by the same part of the cutting edge, and the degree of wear is extremely low. Therefore, the tool life can be greatly extended, and the cutting accuracy can be improved.

By extending the tool life in this way, the cutting speed v can be set to be much higher than in the past, so that the machining time is greatly reduced, and thereby the machining speed can be increased. Further, since there is no need to change the tool during the entire machining process, the machining efficiency is further improved, and further, there is no occurrence of a joint step due to replacement.

As described above, according to this lathe, it is possible to achieve high-speed and high-precision machining by extending the tool life, so that it is possible to consistently perform from roughing to finishing without using conventional grinding. Machining can be performed, thereby greatly reducing equipment costs. In addition, in the case of machining, compared to grinding, any surface roughness can be obtained by adjusting the feed rate f without changing the tool, the tool is small and light in weight, easy to handle, and has automatic change and service life. Recycling of the tool after completion is also possible, so there is an advantage that a large amount of cutting can be taken at a time, and there is an advantage that there is no need to clean and treat a large amount of grinding fluid and grinding wheel powder after processing. The fact that the processing can be omitted is of great significance.

Further, as described above, if the entire area of the tool cutting edge is brought into contact with the workpiece 1 before the machining is completed, the tool cutting edge is worn evenly, so that the reuse of the cutting tool 5 can be prevented. It is possible, and tool grinding at the time of reproduction is also extremely easy.

By slightly shifting the center of curvature of the tool tip to the side farther from the workpiece 1 than the center of rotation of the swivel table 17, crown processing for slightly expanding the center of the workpiece 1 can be performed extremely easily. it can.

It should be noted that the present invention is not limited to the above embodiment, and the same effects can be obtained by adopting the following embodiments.

In the above embodiment, the tool edge is formed in an arc shape, but the edge may be provided in a circular shape, for example, over the entire area around the tool regardless of the magnitude of the central angle. Also, if the cutting accuracy is within an allowable range, the shape may not be a precise arc.

In the above embodiment, cutting is performed by a single cutting tool 5, but in the case of rough machining in particular, conventional small cutting tools may be arranged side by side in the circumferential direction. In addition, a plurality of tools 5 similar to those in the above-described embodiment are arranged in a turret type on the tool stand 6 or are juxtaposed in the circumferential direction.
If the tool can be changed by rotation, the tool changing operation can be performed more smoothly. Further, similarly to a conventional machine tool, it is possible to provide an ATC (Automatic Tool Changer).

〔The invention's effect〕

As described above, the present invention provides a tool table that rotatably supports a tool, a workpiece supporting and rotating unit that supports and rotates a workpiece, and a rotating direction and a rotating axis direction of the workpiece. A lathe provided with feed means for relatively moving the tool stand, wherein the cutting edge of the tool is formed in an arc shape, and the center of curvature of the cutting edge of the tool is slightly shifted to a side farther from the workpiece than the center of rotation of the tool. And a tool rotation driving means for rotating a tool on the tool base, and rotating the tool base with respect to the workpiece so that the center of the workpiece expands. Control means for rotating the tool while moving the tool in the direction, and by moving the tool in the direction of the rotation axis of the workpiece while rotating the tool with respect to the rotating workpiece, as compared with the related art. blade Wear less, it is possible to perform a long process of tool life. Along with this, it is possible to improve the processing accuracy by improving the processing accuracy and the cutting speed, and to improve the processing efficiency by omitting the tool change.

In addition, with the above-mentioned high precision of the processing, the finishing processing can be performed by the same cutting processing as the rough processing, so that the necessity of the grinding processing is eliminated, and thereby, the equipment cost is greatly reduced. Savings can also be achieved.

Further, while rotating the tool around a point slightly eccentric to the side closer to the workpiece than the center of curvature of the cutting edge shape, the rotary shaft is kept fixed with respect to the workpiece in the rotational radial direction. The workpiece is machined into a shape in which the center part expands by relative movement in the direction, so that the workpiece can be processed by simple control that does not require the tool to be moved in the rotational radius direction during machining. There is an effect that the crown can be easily processed.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a lathe in one embodiment of the present invention,
2 is a longitudinal sectional front view of the lathe, FIG. 3 is a lateral sectional side view of the lathe, FIG. 4 is a sectional view taken along line IV-IV of FIG. 6, and FIG. 5 is VV of FIG. 6 is a front view of the carriage in the lathe, FIG. 7 is a plan view of the carriage, FIG. 8 is a flowchart showing a processing method using the lathe, and FIG. 9 is a tailstock of the lathe. It is a top view near a stand. 1. Workpiece (workpiece), 2. Headstock (workpiece supporting and rotating means), 6. Tool table, 10. Motor for vertical feed drive (feeding means), 15 ... horizontal drive Motor (feeding means), 30: turning drive motor (tool rotation driving means), 37: control panel.

Claims (2)

(57) [Claims] 1. A tool base for rotatably supporting a tool, a work supporting and rotating means for supporting and rotating a work, and the tool base in a radial direction and a rotational axis direction of the work. A lathe provided with feed means for performing relative movement, wherein the cutting edge of the tool is formed in an arc shape, and the center of curvature of the cutting edge of the tool is slightly shifted to a side farther from the workpiece than the center of rotation of the tool. And a tool rotation driving means for rotating a tool on the tool base, and moving the tool base in the direction of the rotation axis with respect to the workpiece so as to process the workpiece into a shape in which the center portion expands. A turning means for rotating the tool while rotating the tool. 2. The method according to claim 1, further comprising the step of rotating the workpiece and rotating the tool having an arc-shaped edge around a point slightly eccentric to a side closer to the workpiece than the center of curvature of the edge shape. In contrast, a processing method using a lathe, wherein the workpiece is processed into a shape in which a central portion thereof expands by relatively moving the workpiece in a rotation axis direction while keeping a relative position in a rotation radial direction fixed.