JP2604941Y2 - Cooling structure of main shaft of built-in motor type machine tool - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for a spindle of a machine tool which rotates at a high speed, and more particularly to a cooling structure for a spindle of a machine tool having a simple structure using air for cleaning a tool mounting portion of the spindle. .

[0002]

2. Description of the Related Art In a machine tool, the spindle speed is increased, and a so-called built-in motor type machine tool having a built-in motor at the spindle head can simplify and reduce the structure of a drive unit of the spindle. In recent years, it is rapidly spreading. In such a built-in motor type machine tool, the motor rotor generates heat due to the driving of the motor, and the generated heat of the motor rotor is transmitted to the main shaft to cause thermal displacement and seriously affect machining accuracy. It is necessary to minimize the thermal displacement occurring in the main shaft. As a method of cooling the main shaft, a method in which the outside air is directly guided to the motor rotor by a fan and the heat generated by the motor rotor is released into the outside air, or a cooling device such as a cooling device described in JP-A-64-87130. Some cooling systems supply cooling fluid to the main shaft from outside the head of the main shaft. However, these cooling systems have problems in that the cooling effect is not sufficient, and the system is complicated and expensive, and maintenance is troublesome.

[0003]

By the way, there is a machine tool which has a draw bar which can move forward and backward in a spindle through hole, and which holds a pull stud of a tool mounted on a tool mounting portion at a front end of a spindle by pulling the draw bar and pulling the stud. In general, high-pressure cleaning air is jetted to the tool mounting portion at the time of tool replacement to remove dust and the like adhering to the tool mounting portion and the tool.

Therefore, the present invention utilizes a cleaning air jetted to a tool mounting portion at the tip of a spindle when a tool is attached and detached,
It is an object of the present invention to provide a cooling structure for a spindle of a built-in motor type machine tool which can cool the spindle from the inside of the spindle through hole and which can be easily implemented with a simple configuration.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a cooling structure for a spindle of a built-in motor type machine tool according to the present invention has a tool mounting portion for mounting a tool on one end side, and is provided in a through hole of the spindle. A cooling structure for a spindle of a built-in motor type machine tool in which a tool can be detachably attached to the tool attachment portion by gripping the tool with a drawbar provided to be able to move forward and backward, wherein: A spindle cooling unit provided between the drawbar and the inner peripheral surface of the spindle, an air passage formed in an axial direction from one end to the other end of the drawbar, and a direction orthogonal to the axis of the drawbar. An air outlet which is formed and communicates with the air passage so that air flows from the air passage to the spindle cooling unit; and An air discharge portion for discharging the air, an opening / closing means provided on the one end side of the main shaft through-hole, the opening / closing means for slidingly contacting the outer peripheral surface of the drawbar to open and close the air outlet by the advance / retreat movement of the drawbar, and the air passage And an air supply means for constantly supplying air at a predetermined pressure to the air outlet when the drawbar moves to the one end side for tool exchange. The air outlet is opened by the opening / closing means when the drawbar moves to the other end side for cleaning the tool mounting portion and the tool with air, and the tool is mounted on the tool mounting portion. The air flows into the cooling section and is discharged from the air discharge section at the rear end of the main shaft.

[0006]

The air is constantly supplied into the air passage of the drawbar via the air supply means. When the tool is mounted on the tool mounting part provided on one end side of the spindle, that is,
When the drawbar is moving to the other end, which is the clamp position, the air in the air passage flows from the air outlet into the spindle cooling section, and cools the spindle from the inside. The air heated by taking heat from the main shaft flows to the other end of the main shaft, and is discharged into the outside air from an air discharge portion provided at the other end of the main shaft. When the drawbar is moved to one end, which is the unclamping position, to change the tool, the opening / closing means that slides on the outer peripheral surface of the drawbar closes the air outlet, so that the air in the air passage does not flow to the spindle cooling unit. I do. When the tool is detached from the tool mounting portion, air is jetted from one end of the air passage to the tool mounting portion and the tool, and the tool mounting portion and the tool are cleaned.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a tip portion of a spindle according to an embodiment of the present invention. FIG. 1A shows a state in which the drawbar is retracted to a tool clamping position, and FIG. 1B is a view in which the drawbar advances to a tool unclamping position. FIG. 2 is a sectional view of a rear end portion of the spindle according to the embodiment of the present invention. In this embodiment, a horizontal machine tool having a horizontal spindle axis direction will be described. However, it goes without saying that the present invention can be applied to a vertical machine tool having a vertical spindle axis direction.

A spindle 2 on which a tool holder T with a tool (not shown) is detachably mounted is rotatably attached to a spindle head 1 by a spindle support 3. The main shaft support 3 includes a front bearing housing 4 and a rear retainer 5. The main shaft 2 is supported on the front side by the bearing housing 4 via bearings 6 and 6, and the rear portion of the main shaft 2 is supported by the retainer 5 via a bearing 7. The side is supported and rotatable.

A motor rotor 21 is arranged and fixed on the outer periphery of an intermediate portion of the main shaft 2. On the other hand, a stator 23 is provided on the inner peripheral surface of the motor housing 22 fitted in the spindle head 1 and fixed with bolts, facing the motor rotor 21. The motor for rotating the main shaft 2 is
It is composed of a stator 23, a motor rotor 21 and the like. Between the outer periphery of the motor housing 22 and the spindle head 1, there is provided a flow part 24 through which a cooling fluid such as cooling oil flows, and the cooling fluid supplied from outside the spindle head 1 flows through the flow part 24. By flowing through the inside, the motor 20 and the spindle head 1 are cooled.

At the center of rotation of the main shaft 2, a main shaft through hole 2a penetrating from the front end to the rear end is formed, and a draw bar 10 for holding the tool holder T in the main shaft through hole 2a extends in the main shaft axial direction. It is provided movably forward and backward.
The spindle cooling unit 12 through which air for cooling the heated spindle 2 by transmitting heat generated by the motor rotor 21 is provided between the drawbar 10 in the spindle through hole 2 a and the inner peripheral surface of the spindle 2. I have. A tool mounting portion 2b having a tapered inner peripheral surface for mounting a tool (not shown) is formed at the tip of the main shaft through hole 2a, and an outer diameter of the drawbar 10 is provided behind the tool mounting portion 2b. A drawbar guide 2c whose inner diameter is reduced to the same size as the size is formed.

The tip of the drawbar 10 is supported by its outer peripheral surface slidingly contacting the drawbar guide 2c of the main shaft through-hole 2a. On the other hand, an intermediate portion of the drawbar 10 is supported by two ring-shaped support members 13 provided separately from each other, and a rear end portion of the drawbar 10 is fitted to the drawbar 10 from the rear end side. Screwed nut 19
The support member 18 is supported by a sleeve-shaped support member 18 which is prevented from falling off. The drawbar 10 is held at the center of rotation of the main shaft 2 by the drawbar guide 2c, the support member 13 and the support member 18. The support member 13 has two notches 13a at symmetrical positions on the outer periphery, and the air in the main spindle cooling unit 12 passes through the notches 13a so that the support members 13, 13 have one end to the other end. It can be flowed to. Similarly, the support member 18 also has a notch 18a formed at a symmetrical position on the outer peripheral surface,
The air in the spindle cooling section 12 passes through the notch and is discharged from the air discharge section 11 at the rear end of the spindle 2 into the outside air. In the drawing, reference numeral 8 denotes a plurality of disc springs disposed between the support member 13 and the support member 18, and
Is constantly biased backward (to the right in the drawing).

At the tip of the drawbar 10, a tool holder T
Hole 1 that can be inserted from the rear end of the pull-stat Ta
0b is formed, and a known gripping mechanism for gripping the pullstat Ta is provided. This gripping mechanism is composed of a plurality of steel balls 9 provided so as to be able to come and go in the hole 10b and a tapered surface formed in the main shaft through-hole 2a. It will not be described in further detail. Pullstat T in hole 10b
When the drawbar 10 is retracted by inserting a, the pullstat Ta is gripped by the gripping mechanism and pulled backward, and the tool holder T is held by the tool mounting portion 2b.

An air passage 10a penetrating from the hole 10b to the rear end of the drawbar 10 is formed at the center of rotation of the drawbar 10. Also, on the outer peripheral surface at the tip of the drawbar 10,
An air outlet 10c is formed from one outside and across the air passage 10a to the other outside. The air in the air passage 10a can flow to the main shaft cooling unit 12 through the air outlet 10c. Air outlet 10c
Is provided at a position where it comes into sliding contact with the drawbar guide 2c, and as the drawbar 10 moves forward and backward, the drawbar guide 2
c to open and close. That is, in this embodiment, the drawbar guide 2c of the main shaft through-hole 2a is a means for opening and closing the air outlet 10c. Open and drawbar 1
When 0 moves forward, the air outlet 1 is drawn by the drawbar guide 2c.
0c is closed.

A push rod 15 for advancing the draw bar 10 against the urging force of the disc spring 8 at the time of tool change is provided facing the rear end of the draw bar 10, and is driven in the axial direction of the main shaft by driving a cylinder (not shown). It is possible to move forward and backward. The distal end surface 15 a contacts the rear end surface of the draw bar 10 to push the draw bar 10, and the draw bar 10 can be advanced against the urging force of the disc spring 8. An air passage 16a is formed in the push rod 15, and communicates with a nozzle 16 as an air supply means protruding from the distal end surface 15a. The nozzle 16 is formed slightly smaller than the inner diameter of the air passage 10a so as not to contact the inner peripheral surface of the air passage 10a of the drawbar 10, and a part of the tip is always in the air passage 10a of the drawbar 10. And the push rod 15
The high-pressure air flowing through the air passage 16a can always be supplied to the air passage 10a of the drawbar 10 regardless of the forward / backward movement of the air.

Reference numeral 17 in FIG. 2 denotes an air leakage preventing member slidably fitted to the tip of the push rod 15 together with the coil spring 17a. The air leakage preventing member 17 is for preventing air leaking from between the push rod 15 and the drawbar 10 during tool change from leaking into the outside air. When it comes into contact with the fixing member 14, it comes into contact with the end surface of the ring-shaped fixing member 14 provided at the rear end of the main shaft 2, and is pressed against the fixing member 14 by the urging force of the coil spring 17 a to put the air discharge portion 11 in a sealed state. . The air leak prevention member 17 is provided when the tip surface 15a of the push rod 15 and the drawbar 10 are completely in close contact with each other, and there is little possibility that air supplied from the air passage 16a through the nozzle 16 leaks into the outside air. Need not be provided.

The operation of the cooling structure for the main shaft according to the present invention will be described. The air always flows through the air passage 16a and the nozzle 16 through the air passage 10a in the drawbar 10.
Is supplied within. When a workpiece (not shown) is machined by a tool mounted on the main shaft 2, the drawbar 10 is retracted by the urging force of the disc spring 8.
“c” is open to the spindle cooling unit 12. Therefore, the air supplied to the air passage 10a flows from the air outlet 10c to the spindle cooling unit 12, and flows to the rear end side of the spindle 2 along the inner peripheral surface of the spindle 2 (the air flowing in the spindle cooling unit 12). Is indicated by an arrow in FIG. 2). The main shaft 2 is warmed by the heat generated by the motor rotor 21 by the driving of the motor 20, but the main shaft 2 is cooled from inside by the air flowing through the main shaft cooling unit 12. The air that has taken heat from the main shaft 2 passes through a notch of the support member 18 and is provided at an air discharge portion 1 provided at the rear end of the main shaft 2.
1 is released into the outside air.

When changing tools, a cylinder (not shown) is driven to push forward the push rod 15 and push the draw bar 10 from the rear end side. As a result, the drawbar 10 moves forward against the biasing force of the disc spring 8, so that the air outlet 10c
Is blocked by the drawbar guide portion 2c so that the air in the air passage 10a does not flow to the spindle cooling portion 12. on the other hand,
Tool mounting part 2b by automatic tool changer (ATC)
When the tool holder T is removed from the
The air inside is ejected from the hole 10b at the tip of the drawbar 10 toward the tool mounting portion 2b to clean the tool mounting portion 2b and the tool holder T (the direction in which the air jetted from the tip of the drawbar 10 flows is shown in FIG. 1). (B) indicated by a middle arrow).

Although a preferred embodiment of the present invention has been described, the present invention is not limited to this. For example,
In the above embodiment, the air supply means for supplying air to the air passage 10a has been described as the nozzle 16 having a part of the tip always inserted into the air passage 10a. Alternatively, air may be supplied from an external compressor or the like into the air passage 10a of the drawbar 10. Also, the air outlet 10c has been described as being formed so as to penetrate from the outside of the drawbar 10 to the outside of the other side of the drawbar 10 across the air passage 10a. The outlet 10c may be provided radially. In addition, although the cooling structure of the spindle of the present invention can be expected to have a considerable cooling effect by itself, it can be implemented easily and inexpensively without making significant improvements to the existing spindle. There is a feature that it can be easily combined with a cooling device or a cooling structure, and the spindle can be cooled more effectively.

[0019]

[Effect of the Invention] Since the present invention is configured as described above, the main shaft of the built-in motor type machine tool is connected to the main shaft through-hole by using air for cleaning the tool mounting portion when changing the tool. You can do it from inside. Also,
The cooling structure of the present invention has a simple configuration and can be implemented easily and inexpensively without making significant improvements to the existing spindle, so that it can be easily combined with other cooling devices and cooling structures. In addition, a high machining accuracy can be maintained by increasing the cooling effect of the spindle.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tip portion of a spindle according to an embodiment of the present invention, in which (a) shows a state in which a drawbar is retracted to a tool gripping position, and (b) shows a state in which the drawbar is in a tool unclamping position. This shows a state in which the vehicle is advanced.

FIG. 2 is a sectional view of a rear end portion of the spindle according to the embodiment of the present invention;

[Explanation of symbols]

 T Tool holder Ta Pullstat 2 Main shaft 2a Main shaft through hole 2b Tool mounting portion 2c Drawbar guide (opening / closing means) 3 Main shaft support 4 Bearing housing 5 Retainer 8 Disc spring 10 Drawbar 10a Air passage 10c Air outlet 11 Air discharge portion 12 Main shaft Cooling unit 13 Support member 15 Push rod 16 Nozzle (air supply means) 16a Air passage

Continuation of the front page (56) References JP-A-4-57650 (JP, A) JP-A-3-213243 (JP, A) JP-A-4-51349 (JP, U) JP-A-62-235751 (JP) , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23Q 11/00, 11/12 B23B 19/02, 31/117

Claims (1)

(57) [Scope of request for utility model registration] 1. A tool mounting portion for mounting a tool on one end side, wherein the tool is detachably mounted on the tool mounting portion by gripping the tool with a draw bar provided to be able to advance and retreat in a main shaft through hole. A cooling structure for a spindle of a built-in motor type machine tool, comprising: a spindle cooling unit provided between the drawbar in the spindle through hole and an inner peripheral surface of the spindle; and one end of the drawbar. An air passage formed in the axial direction to the other end, and air formed in a direction orthogonal to the axis of the drawbar, and communicating with the air passage so that air flows from the air passage to the main shaft cooling unit. An outlet, an air discharge unit provided at the other end of the main shaft to discharge air in the main shaft cooling unit to the outside air, and an air discharge unit provided at the one end of the main shaft through-hole and sliding on an outer peripheral surface of the drawbar. contact Opening / closing means for opening and closing the air outlet by moving the drawbar forward and backward; and air supply means for constantly supplying air at a predetermined pressure to the air passage.The drawbar is provided at the one end side for tool exchange. When moved, the air outlet is closed by the opening / closing means, and the tool mounting portion and the tool are cleaned by the air flowing through the air passage, and the drawbar is connected to the other end to mount the tool on the tool mounting portion. Wherein the air outlet is opened by the opening / closing means when moved to the side, air flows from the air passage to the main shaft cooling portion, and is discharged from the air discharge portion at the rear end of the main shaft. Cooling structure for the main shaft of a machine tool.