JP2002346809A - Cutting tool for perforating process and perforating method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obviately prevent lowering of processing precision, in processing of a reverse tapered hole, by an edge being put back oppositely from the cutting direction, which originate the shortage of rigidity of a machine tool, in processing of the reverse tapered hole. SOLUTION: In the case of processing the reverse tapered hole with a processing mode of tool rotational type using a cutter 1 having a cutting blade 4, coolant is injected from a coolant injection nozzle 7 which is opened at an opposite position to the cutting blade 4. The power due to processing which is going to thrust back the cutting blade 4 to an opposite direction against a cut-in direction (a radius enlarging direction) load is offset with the thrust accompanying the above-mentioned coolant injection, and a reduction in processing accuracy of the reverse tapered hole is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool for boring and a boring method using the tool, and more particularly to a highly versatile machine such as a machining center using a so-called single-point or single-flute type tool. The present invention relates to a drilling cutting tool suitable for performing high-precision drilling with a machine and a drilling method using the tool.

[0002]

2. Description of the Related Art As a method of boring a tool, there is, for example, a boring method called finishing boring, which is a single point (single chip) or a single blade type cutter such as a straight blade. By performing the cutting process, it is easy to guarantee the accuracy of the hole diameter.

Here, when the focus is on the machining accuracy of the hole diameter, it is effective to specially machine only a portion requiring high accuracy by using a special machine tool. From the viewpoints of economy and high-mix low-volume production, machining using a more flexible and versatile machining center is being replaced. The above-mentioned finishing boring is not an exception, and is being performed in a machining center as a tool-rotating type working.

The machining center is a multipurpose numerically controlled machine tool with high versatility, and has at least three degrees of freedom in X, Y, and Z orthogonal axes in addition to an automatic tool change function. For example, the main axis is horizontal (horizontal posture). In the case of the horizontal machining center set to, the main shaft supported by the vertically long column movable in two directions in the horizontal direction moves vertically with respect to the column. As a result, the rigidity in the horizontal direction (lateral direction) tends to be lower than the rigidity in the vertical direction of the machine.

[0005] When cutting is performed by the above-mentioned single point (single chip) or single blade type cutter in a machining center having such characteristics, the influence of the reaction force (back force) due to the processing load. For this reason, a force in the direction of pushing back the cutter acts, particularly in the lateral direction where the rigidity tends to be insufficient, the machine itself causes microscopic bending, so that the processing hole shape is slightly smaller than the regular size and as shown in FIG. 9, for example. Therefore, there is a limit in improving the precision of the processing hole shape, that is, in improving the dimensional accuracy and the roundness accuracy.

[0006] In addition, the conventional machining method using a machining center aims at improving chip dischargeability and suppressing a rise in the temperature of the cutting edge of the cutter and the workpiece while coping with high-speed machining. Is an aluminum alloy or the like, a coolant as a cutting oil is supplied through the tool holder and the cutter at a pressure of about 2 MPa so that the coolant is sprayed directly from the position immediately near the processing point toward the cutting edge. This method is called a center through coolant system or the like. Therefore, the thrust accompanying the injection of the coolant is added to the force for pushing back the cutter, which further promotes the deterioration of the machining hole accuracy, which is not preferable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and in particular, has been made in view of the above-mentioned problem. An object of the present invention is to provide a cutting tool and a hole drilling method using the tool.

[0008]

According to a first aspect of the present invention, there is provided a tool for performing a cutting process on an inner peripheral surface of a hole with a single point-shaped or linear cutting edge. The cutting oil injection hole which opens at a position almost diametrically opposite to the cutting edge across the center of the body is provided.

[0009] The above-mentioned tool may be of a type in which a cutter is mounted on a predetermined tool holder in addition to a tool configured as a tool by using a cutter alone. It also includes rotary type processing. Further, any type of machine tool other than the machining center may be used as the machine tool.

According to a second aspect of the present invention, there is provided a hole drilling method using the tool according to the first aspect of the present invention, wherein a hole is cut from a cutting oil injection hole to cancel a cutting reaction force by a single cutting edge. It is characterized in that cutting is performed while spraying a predetermined cutting fluid toward the inner peripheral surface of the.

Therefore, according to the first and second aspects of the present invention, when the cutting process proceeds while the inner peripheral surface of the processing hole and the single cutting edge rotate relative to each other, the cutting oil When a predetermined cutting oil is injected from the injection hole toward the inner peripheral surface of the processing hole being processed, some thrust is generated with the injection of the cutting oil. Since the cutting fluid injection hole is opened at a position opposite to the single cutting edge, the thrust associated with the injection of the cutting fluid is subjected to the reaction force (back force) due to the processing load as described above. ), The force in the direction of pushing back the cutter is antagonized, and both forces cancel each other.

As a result, as described above, even if the lateral rigidity of a horizontal machining center as a processing mother machine is smaller than that in the vertical direction, the machine itself does not bend, and the processing hole shape accuracy is reduced. Will be improved. Of course, the injected cutting fluid also exerts the original cooling and chip discharge promoting effects.

According to a third aspect of the present invention, there is provided a method for drilling a hole on a machine tool such as a machining center having an automatic tool changing function using the tool according to the first aspect, wherein the single cutting edge is used. In order to cancel the cutting reaction force, cutting is performed while spraying a predetermined cutting fluid from the cutting fluid injection hole toward the inner peripheral surface of the hole, while cutting is performed according to the newly selected tool when changing tools. It is characterized in that the supply pressure of the cutting fluid is variably controlled so as to be the oil ejection pressure.

In the case where a plurality of tools having a single cutting edge are to be changed while holding a plurality of tools using an automatic tool changing function of a machining center or the like, the thrust caused by the injection of the cutting oil is used as described above. In order to offset the push-back force, the desired effect cannot be obtained unless the injection pressure of the cutting oil, that is, the supply pressure, is changed for each type of tool having a different size, and in accordance with the processing load.

Therefore, for example, a proportional electromagnetic pressure control valve is interposed as a cutting oil supply pressure variable means in the cutting oil supply path on the machine side, and the optimum cutting oil supply pressure is set in advance for each tool, and this is set to It is stored in advance in association with ID information unique to the tool. When the selection and replacement of a tool are performed using the ID information unique to the tool, the proportional electromagnetic pressure control valve is simultaneously variably controlled to switch the cutting oil supply pressure so that the cutting oil injection pressure suitable for the tool is obtained. .

Thus, even when the tool is changed, a thrust based on the cutting oil spray pressure suitable for the tool can always be obtained.

[0017]

According to the first and second aspects of the present invention, the force for pushing back the tool due to the machining load is offset by the thrust accompanying the injection of the cutting fluid from the cutting fluid injection hole. Therefore, even if there is a rigidity imbalance on the machine side, there is no influence on the shape accuracy of the processing hole, and the processing accuracy is greatly improved as compared with the related art.

According to the third aspect of the present invention, even when a tool is changed by using an automatic tool changing function of a machining center or the like and a hole is drilled, an optimum cutting oil injection pressure corresponding to the type of the tool is set each time. Since the switching is performed, the force for pushing back the tool is canceled out in the same manner as described above, regardless of which tool is used for machining, and the machining accuracy is greatly improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 4 show a first preferred embodiment of a drilling tool according to the present invention, which is used for finishing a so-called reverse tapered hole having a large diameter on the back side. An example is shown.

As shown in FIGS. 1A and 1B, a cutter 1 as a finish cutting tool (a drilling cutting tool) is bent at the tip of a straight shank 2 into a substantially rectangular shape. The body 3 is integrally formed, and the body 3 is formed with a single cutting edge 4 such as a straight blade inclined at a predetermined angle according to the shape of the tapered hole to be machined. When the diameter at the cutting edge 4a, which is the tip of the body 3, is b, the diameter d at the root of the body 3 is formed to be smaller by the depth c of the clearance groove 5 at the root (d =
bc). Further, as shown in FIG. 3, the length L2 of the cutting edge 4 is set slightly larger than the length M of the reverse tapered hole T1 after the rough cutting (L2> M). In addition, body 3
Is formed in a fine multi-sided shape as shown in FIG.

As shown in FIG. 1 and FIG. 2, a coolant supply hole 6 is formed in the cutter 1 so as to extend to the body 3 side while penetrating the axis of the straight shank 2. One end of the coolant supply hole 6 is open to the end face of the straight shank 2, while the other end is a coolant injection nozzle 7, for example, a cutting oil injection hole having a diameter of about 1 mm, at a position opposite to the cutting blade 4 in the body 3. That is, the body 3 is opened at a position substantially opposite to the cutting edge 4 with respect to the center of the body 3.

As shown in FIG. 4, when the cutter 1 is mounted on, for example, a main spindle (spindle) of a machining center via a tool holder 8, the coolant supply hole 6 has a port formed in the tool holder 8 and the main spindle itself. It is connected to a coolant supply source (not shown) attached to the machining center via P to supply a coolant as a cutting oil at a predetermined supply pressure.

Here, the coolant injection nozzles 7 do not necessarily have to be a single one, but are arranged in a line along the longitudinal direction of the body 3, for example, within a range that does not affect the strength or the like of the cutter 1 itself. Or a plurality of them may be arranged in the circumferential direction.

Therefore, in the finish cutting of the tapered hole using the cutter 1, as shown in FIG. 3A, the cutting edge 4a is previously determined and positioned at a fixed angle stop position, and rough cutting is performed. The two-axis simultaneous control of the machining center is performed while the small diameter side mouth portion of the reverse tapered hole T1 and the tip surface of the cutter 1 on the body 3 side are opposed to each other.
While maintaining a constant gap between the cutting edge 4 and the inner peripheral surface of the inverted tapered hole T1, the body 3 of the cutter 1 is removed from the inverted tapered hole T1.
At the same time, the movement is stopped when the axis O2 of the inverted tapered hole T1 coincides with the axis O1 of the cutter 1 (straight shank 2) as shown in FIG. Let it. In FIG. 3, the coolant injection nozzle 7 is not shown in order to avoid complication of the drawing.

Subsequently, from the state where the axis O2 of the reverse tapered hole T1 and the axis O1 of the cutter 1 coincide with each other, the cutter 1 is driven to rotate together with the main shaft, and the cutter 1 is further cut from the reverse tapered hole T1 as cutting feed. Feed in the direction of extracting As a result, the reverse tapered hole T1 of the work W is subjected to finish cutting as shown in FIG.

At the time of this finish cutting, as shown in FIG. 4, a coolant is supplied at a predetermined pressure through a coolant supply hole 6 and a coolant injection nozzle opened at a position opposite to the cutting edge 4. 7 is sprayed toward the inner peripheral surface of the reverse tapered hole T2 to promote the cooling of the part directly controlling the cutting and the discharge of the chips.

At the same time, by injecting the coolant from the coolant ejection nozzle 7, the rotating cutter 1 generates a thrust in the direction of pressing the cutting edge 4 against the inner peripheral surface of the inverted tapered hole T2. This thrust is nothing less than a force that opposes the force for pushing back the cutting edge 4 to which the cutting feed is given in the opposite direction due to the cutting load, and the thrust accompanying the coolant injection and the pushing back force of the cutting edge 4. Will be offset by each other.

As a result, as described above, even if there is an imbalance in rigidity between the horizontal direction and the vertical direction (vertical direction) as a specialty of the machining center, which is a general-purpose compound machine tool, the coolant injection Accompanying thrust and cutting edge 4
Are offset each other, the machine itself does not bend due to the push-back force of the cutting blade 4, and the processing accuracy of the reverse tapered hole T2 is greatly improved as compared with the conventional case. .

After the finish cutting of the inverted tapered hole T2 is completed, the cutting edge 4 of the cutter 1 as shown in FIG.
The spindle is slightly returned in the counter-feed direction by using the degree of freedom of the machining center so as to separate from the inner peripheral surface of the reverse tapered hole T2. Index to the stop position. Then, as shown in FIG. 9E, the machining is performed by retreating the cutter 1 together with the main spindle along the inclination of the reverse tapered hole T2 in the reverse procedure to that at the time of the previous cutter insertion by the simultaneous control of the machining center by two axes. The reverse taper hole T2 is slowly extracted and the finish cutting of the reverse taper hole T2 is completed.

FIGS. 5 and 6 show a second embodiment of the present invention, in which the present invention is applied to a boring bar 10 as a boring tool.

As shown in FIGS. 5 and 6, a relatively long boring bar 10 has a bar body 11 and a tool holder 12 which are bodies formed beforehand integrally with each other.
A substantially triangular throw-away tip (hereinafter, simply referred to as a tip) 14 having a single-point cutting blade 14a is detachably attached to the tip of the cartridge 1 via a cartridge 13. Note that, here, it is assumed that the tool rotation type machining using a machining center is performed in the same manner as described above, and the trajectory circle formed by the cutting edge 14a with the rotation of the boring bar 10 is slightly larger than the diameter of the bar main body 11. Is set.

A coolant supply hole 15 is formed in the bar body 11 so as to penetrate the bar body 11 in the longitudinal direction. One end of the coolant supply hole 15 is connected to the tool holder 1.
2 is connected to a coolant pipe 17 on the main shaft 21 side of the machining center via a coolant pipe 16 attached to the machine 2 itself, and the other end of the coolant supply hole 15 is a chamfered portion 18 on the tip end surface of the bar body 11. At the position opposite to the cutting edge 14a of the tip 14, that is, at the position opposite to the cutting edge 14a with respect to the center of the bar body 11, a coolant injection nozzle 19 as a cutting oil injection hole is opened.

When the boring bar 10 is mounted on the spindle 21 of the machining center with the tool holder 12, for example, the coolant supply hole 15 is provided through the coolant pipes 16 and 17 to the coolant supply device 20 attached to the machining center. And a coolant is supplied at a predetermined supply pressure. When the spindle 21 and the boring bar 10 are automatically attached / detached using the automatic tool change function of the machining center, attachment / detachment of the coolant pipes 16 and 17 is performed at the same time.

Therefore, according to the present embodiment, when the inner peripheral surface of the hole H of the work W is cut by the tool rotation type machining mode, the coolant injection nozzle 19
As in the first embodiment, when the coolant is injected, the thrust generated by the coolant injection and the force for pushing back the cutting edge 14a in the direction opposite to the cutting direction due to the processing load are generated. They are mutually opposed and cancel each other, so that the influence of the unbalance of the rigidity of the machining center on the processing accuracy is avoided, and high-precision processing can be performed.

Here, a plurality of single-point boring bars 10 having different processing diameters are prepared in the tool magazine of the machining center, and the boring bar 10 is changed using the automatic tool changing function to perform a plurality of types of holes H. In this case, since the machining load varies depending on the machining hole diameter, the magnitude of the thrust to be obtained by the coolant injection as described above, or the coolant supply pressure, also depends on the size or type of the boring bar 10. It is necessary to adjust each time.

In view of the above, since unique ID information is given to each tool to be subjected to automatic tool change in the machining center, an optimum coolant supply pressure for each boring bar 10 is set in advance. Then, it is stored in association with the unique ID information.

On the other hand, as shown in FIG. 5, a coolant supply device 2 including a coolant supply pump (not shown) and the like is provided.
From 0 to the supply path 22 for supplying the coolant to the coolant supply hole 15 of the boring bar 10 mounted on the main shaft 21, a proportional electromagnetic pressure control valve (proportional solenoid valve) 24 together with an open / close solenoid valve 23 is provided. It shall be interposed. The proportional electromagnetic pressure control valve 24 is a type of electromagnetic valve that can control the discharge-side pressure in a stepless manner by adjusting the opening degree thereof in accordance with a command current (voltage).

When an automatic tool change command is issued, a corresponding boring bar 10 is determined from a group of tools stored in a tool magazine based on the ID information, and is mounted on the spindle 21. The drilling bar 1 newly selected at that time is
The corresponding coolant supply pressure is read out based on the ID information of 0, and the proportional electromagnetic pressure control valve 24 shown in FIG.
To switch the coolant supply pressure.

By doing so, the boring bar 10
Even when a plurality of holes having different hole diameters are drilled while changing the coolant supply pressure, a coolant supply pressure suitable for the corresponding boring bar 10 and, consequently, an optimum thrust accompanying coolant injection can be obtained.

FIG. 8 shows a front view of a boring bar 30 similar to the above as a third embodiment of the present invention.

In this embodiment, a coolant supply hole 33 is formed in the axis of the bar body 31 which is a body on which the chip 32 is mounted, and the coolant supply hole 33 is opened at a position substantially opposite to the cutting edge 32a of the chip 32. Coolant supply hole 3
Coolant injection nozzle (cutting oil injection hole) communicating with 3
34 are formed. Further, apart from the coolant injection nozzle 34, a plurality of auxiliary nozzles 35 are radially opened so as to shift their positions in the circumferential direction with respect to each other. These auxiliary nozzles 35 are also provided in the coolant supply holes 33. Communicating. Note that the coolant injection nozzle 34 and the plurality of auxiliary nozzles 35 may coincide with each other in the axial direction of the bar main body 31 or may be offset by a predetermined amount in the axial direction of the bar main body 31. May be.

Therefore, according to the present embodiment, the injection of the coolant from the coolant injection nozzles 34 and the auxiliary nozzles 35 is appropriately adjusted by adjusting the hole diameters of the coolant injection nozzles 34 and the auxiliary nozzles 35 as well as the injection pressure. The same effects as in the above embodiments can be obtained by canceling the force for pushing back the cutting edge 32a in the direction opposite to the cutting direction for the processing load with the sum of thrusts accompanying become.

[Brief description of the drawings]

FIG. 1 is a view showing a tool (cutter) for machining a reverse tapered hole as a first embodiment of the present invention, wherein (A) is a side view thereof, and (B) is an arrow a direction in FIG. View.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a process explanatory view showing a finish cutting method for a tapered hole when the cutter shown in FIG. 1 is used.

FIG. 4 is an explanatory view at the time of coolant injection in FIG. 3;

FIG. 5 is a configuration explanatory view showing details of a boring bar as a second embodiment of the present invention.

FIG. 6 is a right side view of the boring bar shown in FIG. 5;

FIG. 7 is a flowchart showing a procedure at the time of tool change in the machining center.

FIG. 8 is an explanatory front view showing a structure of a boring bar according to a third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing the effect of roundness accuracy due to rigidity imbalance in a machining center for drilling.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cutter (cutting tool for hole processing) 3 ... Body 4 ... Cutting edge 6 ... Coolant supply hole 7 ... Coolant injection nozzle (cutting oil injection hole) 10 ... Boring bar (cutting tool for hole processing) 11 ... Bar body (body) 14 ... Indexable insert 14a ... Cutting blade 15 ... Coolant supply hole 19 ... Coolant injection nozzle (cutting oil injection hole) 30 ... Boring bar (cutting tool for drilling holes) 31 ... Bar body (body) 33 ... Coolant supply hole 34 … Coolant injection nozzle (cutting oil injection hole) 35… Auxiliary nozzle

Claims (3)

[Claims] 1. A tool for cutting an inner peripheral surface of a hole with a single pointed or straight cutting edge, wherein a center of the body provided with the cutting edge is A cutting tool for drilling holes, wherein a cutting fluid injection hole is formed at a position substantially opposite to the cutting edge. 2. A hole drilling method using the tool according to claim 1, wherein the cutting oil is injected from an injection hole toward an inner peripheral surface of the hole so as to cancel a cutting reaction force generated by the single cutting edge. A hole drilling method characterized in that cutting is performed while spraying a predetermined cutting fluid. 3. A method for drilling a hole in a machine tool having an automatic tool changing function using the tool according to claim 1, wherein a cutting fluid is injected to cancel a cutting reaction force by the single cutting edge. Cutting is performed while injecting a predetermined cutting fluid from the hole toward the inner peripheral surface of the hole, and when changing tools, the cutting fluid is adjusted so that the cutting fluid ejection pressure matches the newly selected tool. A hole drilling method characterized by variably controlling a supply pressure of a hole.