JPH0761594B2 - Machine tool headstock - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a headstock of a machine tool, particularly a machine tool such as a precision lathe for machining OA parts, optical parts, electronic machine parts and the like.

[Conventional technology]

In general, machine tools, especially machine tools such as precision lathes for processing OA parts, optical parts, electronic machine parts, etc., have rigidity so that the main axis is not distorted by reaction when turning. A solid headstock is provided to improve This headstock is a component that has a significant effect on machining accuracy.Therefore, the frictional heat generated between the main shaft and the bearing as the machine operates and the gap between the main shaft and the bearing Great care must be taken with respect to cutting oil and the penetration of fine chips contained in the cutting oil.

Conventionally, precision bearings have been used for the headstock bearings, and high-quality grease of approximately 15% of the bearing space capacity is applied to the precision bearings.
The heat generated by lubricating oil agitation was suppressed.

Further, as described in Japanese Utility Model Laid-Open No. 61-144943, a plurality of radially projecting fins are provided on the outer periphery of a spindle casing that holds a tool rotating spindle through a plurality of bearings. It is equipped with a spindle support base with concave surfaces that are spaced apart from each other, and an impeller is attached to the rear end of the spindle so that the rotational friction heat generated in the bearing is radiated from the fins by the air flow generated in the impeller. Cooling structures are known.

Further, as described in Japanese Utility Model Laid-Open No. 61-131254, a heat radiating fin or a heat radiating ring is fitted inside the bearing to a tool rotating spindle held in a spindle casing via bearings in the axial direction. There is known a cooling structure for a spindle of a machine tool which is attached and sends air to a radiating ring through a hole penetrating from the outside of the spindle casing to radiate rotational frictional heat generated in a bearing by air.

[Problems to be solved by the invention]

However, in these conventional techniques, when high-quality grease is used, although the amount of grease used is small, it is unavoidable that rotational frictional heat is generated in the bearing portion as the main shaft rotates. At the end where the spindle protrudes from the spindle casing, a labyrinth that narrows the gap between the two is provided for high-speed shaft sealing.This labyrinth converts the kinetic energy of the grease into heat energy, and the grease is transferred to the outside of the spindle casing. Although it prevents leakage, even with such a structure, a perfect seal cannot be obtained, and therefore fine chips contained in the cutting oil will rotate with the rotating spindle and spindle as the machine tool operating time elapses. It sometimes penetrated into the gap with the casing and adversely affected the precision bearing. In addition, even if the quality of the cutting oil is optimal for the workpiece material, the additives contained in the cutting oil may cause a chemical change in the high-quality grease applied to the precision bearings. It was necessary to pay close attention to the selection.

In the cooling structure for the spindle of the machine tool described in Japanese Utility Model Laid-Open No. 61-144493, the impeller that produces cooling air is attached to the rear end of the spindle, so the entire spindle casing is cooled. However, since it is air-cooled from the rear part of the main shaft casing, there is a problem that it takes time to cool the front bearing part as the tool mounting part or the workpiece mounting part, which is the most important part for machining accuracy. Furthermore, since the cooling air is blown from the rear part of the main shaft casing, the cooling air for cooling the front part of the main shaft casing has already taken away heat in the rear part and the central part of the main shaft casing, so that the cooling efficiency of the front part of the main shaft casing is There is a problem of being bad. Therefore, if the cooling impeller is attached to the front end of the spindle, the above problems will be solved to some extent, but it will be necessary to secure a space for installing the cooling impeller in the spindle casing. Since the overhang distance to the surface becomes large, it cannot be said that it is a good measure for maintaining processing accuracy. Further, in the processing using cutting oil, the cooling impeller scatters the cutting oil toward the headstock, which not only causes the cutting oil to enter the rotating portion but also deteriorates the working environment.

Further, in the cooling structure for the spindle of the machine tool described in Japanese Utility Model Laid-Open No. 61-131254, since the vicinity of the bearing portion that generates the rotational frictional heat that is the heat source is cooled, the conventional example described above is used. Although the cooling efficiency is better than that of, the air supply device for sending the cooling air to the heating fins or the heat radiation ring is required, and the supplied air pressure and air amount are constant with respect to the change of the main shaft rotation speed. Therefore, if the air pressure supplied by the air supply device is excessively high, there is a high risk that the lubricating oil enclosed in the rotating portion will be washed away, and conversely, if the air pressure is lower than necessary, the labyrinth effect will be insufficient. There is a problem that fine cutting chips from the outside enter the bearing portion, and there is a disadvantage that it is difficult to adjust and maintain the optimum supply air pressure. Further, since the amount of air blown to the front bearing and the rear bearing cannot be independently controlled, it is difficult to perform cooling according to the bearing condition.

The object of the present invention was devised in view of such circumstances, and cools heat disliked in precision machining in the vicinity of the source of the heat, and at the same time, adjusts the air supply pressure and the supply amount by rotating the main shaft. It uses a part of the rotational drive force of the main shaft to change the speed with a forward characteristic and further eliminates the need for an external air supply device. In addition, oil taken in from the outside, fine cutting chips, etc. A machine tool that has a filter function in the air inflow path to prevent foreign matter from entering and cools the bearing of the spindle, which is the source of heat, and maintains the quality of the grease applied to this spindle bearing. Is to provide the headstock of.

[Means for solving problems]

The present invention is configured as follows in order to solve the above problems and achieve the above objects. That is, a headstock of a machine tool according to the present invention rotatably supports a main shaft in a main shaft casing via a pair of bearings, attaches a blower to the main shaft between the bearings, and the blower sucks air through an air suction passage. And air is blown to the bearing, and an air discharge passage having a pressure adjusting valve is formed in the main shaft casing at a portion between the blower and the bearing to adjust an air flow rate to the bearing. The headstock of the machine tool will be described in more detail. The air suction passage is formed in the main spindle casing, and the air suction passage is provided with a filter and a one-way valve. There is a pair of blades mounted at opposite mounting angles with respect to the axis, and the empty suction passage radially penetrates the main shaft casing and the main shaft and the main shaft case. Is formed so as to communicate with a first space portion formed between the blades surrounded by a single shaft, or the air suction passage penetrates the main shaft and is surrounded by the main shaft and the main shaft casing. A labyrinth is formed so as to communicate with the first space formed between the blades, and further, a labyrinth is formed between the main shaft and the main shaft casing on the axially outer side of the bearing. Regarding the headstock of machine tools.

[Action]

Since the headstock of the machine tool according to the present invention is configured as described above, it operates as follows. That is, when the main shaft is rotated to perform processing such as cutting on the workpiece, the blades of the blower attached to the main shaft rotate. Since the pair of blades, that is, the front blade and the rear blade, of the blower are mounted such that the mounting angles thereof are opposite to each other, as the rotation speed of the blower, that is, the rotation speed of the main shaft, increases, The pressure in the first space portion located between the front blade and the rear blade and formed between the main shaft and the main shaft casing is lower than atmospheric pressure and is negative pressure. Air filtered by a filter from the outside flows into the negative first space through the air suction passage via the one-way valve. Initially, the air in the first space and the subsequent inflow air have the mounting angles of the front blade and the rear blade opposite to each other as described above, and therefore the front bearing and the rear bearing pass through these both blades. Toward the second space portion formed between the bearing and the blower. Part of the air that has flowed into the second space portion is released to the outside air through the labyrinth formed between the main shaft and the main shaft casing while absorbing the rotational frictional heat generated in each of the bearings.
Further, the rest of the air that has flowed into the second space passes through the air discharge path and is also discharged to the outside air, but the labyrinth of the total inflow air is removed by the pressure control valve provided at the discharge port of the air discharge path. The distribution ratio between the amount of air released through the pressure control valve and the amount of air released through the pressure control valve is adjusted. Further, since the blower attached to the main spindle rotates and sucks in air due to the rotation of the main shaft, the inflowing air has an air amount proportional to the rotation speed of the main shaft and the rotation speed of the main shaft. It has an air pressure proportional to the square of the velocity.

〔Example〕

An embodiment of a headstock of a machine tool according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a vertical sectional view showing a structure in which a headstock is cut along a vertical plane including a rotation axis of the main shaft.

The headstock 1 mainly includes a main shaft 2 and a main shaft casing 5 that rotatably supports the main shaft 2 with a pair of bearings, that is, a front bearing 3 and a rear bearing 4 in the front and rear directions of the rotation axis AA.
This spindle 2 has a through hole 6 through which an operating rod penetrates in the center for operation of a chuck or the like which will be described later, and the front end portion 7 has a shape in which the diameter of the hole connected to the through hole 6 is enlarged. The chuck mounting surface 8 is configured so that a cutting tool, a workpiece mounting chuck, etc. can be mounted. A main shaft drive pulley 10 is attached to a rear end portion 9 of the main shaft 2 by a well-known means such as a key, a key groove, and a set screw. The main shaft drive pulley 10 is driven by a drive source (not shown) via a belt to rotate and drive force. Is given to rotate the spindle 2.

The main shaft casing 5 surrounds the main shaft 2 over substantially the entire length between the front and rear ends 7, 9 of the main shaft 2, and the lower installation part
It is installed on a machine body (not shown) by 11. The main shaft 2 includes a front end portion 7, an inner race portion 43 of the front bearing 3, an intermediate portion 45 that supports the spacer 12, and an intermediate portion that supports the blower 40.
13, an inner race portion 44 of the rear bearing 4, an intermediate portion 46 that supports the spacer 14, and a rear end portion 9. These portions have outer peripheral surfaces whose outer diameters become smaller in that order. Further, according to these outer diameters, the main shaft casing 5
Is an intermediate portion 49 that supports the outer race portion 47 and the spacer 15 of the front bearing 3, an intermediate portion 16 where the blower 40 is located, and an intermediate portion that supports the outer race portion 48 and the spacer 17 of the rear bearing 4.
50, and these parts are formed on the inner peripheral surface of which the inner diameter becomes smaller in that order. Therefore, when inserting the main shaft 2 into the main shaft casing 5, with respect to the main shaft 2, one front bearing pressing member 18 is fitted to the outer peripheral surface of the front end portion 7, and then the front bearing 3, the spacer 12 and the spacer 15 are inserted. The desired number (3 in the figure) are fitted, and the front bearing 3 is fixed by the other front bearing pressing member 19 screwed to the main shaft 2.
Install in advance. Next, the blower is installed in the middle portion 13 of the main shaft 2.
Fit and fix 40. Finally, the spacers 14 and the spacers 17 are fitted to the intermediate portion 46 of the main shaft 2 in a desired number (two in the figure). Of course, the spindle drive pulley 10 is not attached at this stage. On the other hand, the rear bearing pressing member 20 is screwed to the rear end of the main shaft casing 5, and the main shaft 2 is inserted into the main shaft casing 5 from the front in this state, so that the outer race portion 48 of the rear bearing 4 becomes the main shaft casing. Rear bearing retainer 20 on 5 side
When it comes into contact with, the bolt 21 penetrating the front bearing pressing member 18 on the front side is screwed into the spindle casing 5. As a result, the spindle 2 is attached to the spindle casing 5.

When the front front bearing holding member 18 is screwed with the bolt 21, the inner peripheral surface of the front bearing holding member 18 and the front end portion 7 of the main shaft 2 are fixed.
A front labyrinth 22 is formed between the outer peripheral surface and the outer peripheral surface. On the rear end 9 side of the main shaft 2, by screwing the inner rear bearing pressing member 23 into the male screw portion 14a formed on the main shaft 2 of the rear bearing 4 toward the rear bearing 4, the inner race of the rear bearing 4 is A rear labyrinth 24 is formed between the inner peripheral surface of the outer rear bearing pressing member 20 and the outer peripheral surface of the inner rear bearing pressing member 23 while preventing the portion 44 from slipping out. Finally, the spindle drive pulley 10 is fixed to the rear end portion 9 of the main spindle 2 by keying and fixed, and then the machining tool, chuck, etc. are attached to the chuck mounting surface 8 of the front end portion 7 to assemble the headstock 1. It can be carried out.

Next, the blower 40 attached to the main shaft 2 will be described with reference to FIGS. 2 and 3. The blower 40 is composed of a blower front blade 25 and a blower rear blade 26 (in the illustrated example, each of the blades is composed of four blades). The blower front blades 25 and the blower rear blades 26 are respectively attached to the outer peripheral surface of the intermediate portion 13 of the main shaft 2 in the middle of the front bearing 3 and the rear bearing 4 with respect to the rotation axis AA. However, as shown in FIG.
They are attached in opposite directions as represented by angle α and angle −α.

Further, the inner and outer peripheral surfaces of the intermediate portion 16 of the main shaft casing 5 are configured so as to form a slight gap 27 between the outer diameter tips of the blower front blade 25 and the blower rear blade 26. The casing 5 does not prevent the rotation of the main shaft 2 and efficiently sends out suctioned air as described later.

A first space 28, which is defined by the outer peripheral surface of the intermediate portion 13 of the main shaft 2 and the inner peripheral surface of the intermediate portion 16 of the main shaft casing 5, between the front blade 25 and the rear blade 26 of the blower serves as a negative pressure chamber. Formed in front of the blower front blades 25 and behind the front bearings 3 and behind the blower rear blades 26 and in front of the rear bearings 4, both the outer peripheral surface of the intermediate portion 13 of the main spindle 2 and the main spindle. Between the inner peripheral surface of the intermediate portion 16 of the casing 5 and the front pressure chamber
29 and the second space part which is the post-pressurization chamber 30 is formed.
In the first space portion 28 which is the negative pressure chamber, the main shaft casing 5
A plurality of air suction passages 31 penetrating in the radial direction communicate with each other, and an air inlet 32 communicating with the outside air of the air suction passage 31 has a filter 33 for filtering the inflowing outside air and a one-way valve 34 that opens only in the air inflow direction. It is provided. Further, the front pressure chamber 29 and the rear pressure chamber 30 are connected to an air discharge passage 35 which penetrates the main shaft casing 5 and communicates with the outside air. Each of the air discharge ports 36 communicating with the outside air of the air discharge passage 35 has a front pressure chamber pressure adjusting valve.
36a and a rear pressurizing chamber pressure adjusting valve 36b are provided.

Further, the air suction passage communicating with the first space portion, which is the negative pressure chamber, is provided on the first casing instead of the first casing.
It may be provided on the main shaft 2 side as indicated by an imaginary line 37 in the drawing. That is, a plurality of air suction passages 37 extending in the radial direction from the through hole 6 of the main shaft 2 and communicating with the negative pressure chamber 28 may be provided, and the intake suction passage 37 may be provided with the filter 38 and the one-way valve 39. Of course, the air suction passages 31 and 37 may be formed on both the main shaft casing 5 and the main shaft 2, or may be formed on either the main shaft casing 5 or the main shaft 2. It is a thing.

Next, the operation of the headstock of the machine tool according to the present invention will be described. The arrows shown in the figure indicate the flow direction of the cooling air or the exhaust air. When the main spindle 2 on which the processing tool, the work, etc. are mounted is rotated by the rotational driving force from the main spindle driving pulley 10, the blower blades 25, 26 are also rotated, and the air in the negative pressure chamber, that is, the first space portion 28 is applied to each of them. Send to pressure chambers 29 and 30. As a result, the pressure in the first space portion 28 starts to decrease, and the outside air starts to be sucked through the air suction passage 31. The filter 33 provided at the air inlet 32 of the air suction passage 31 filters foreign matter such as dust in the outside air so as not to adversely affect the rotation of the main shaft 2. Also, the one-way valve 34 of the air inlet 32
Is set to open when air enters. Blower blade
The air sent from each of the bearings from 25, 26 to the pressure chamber 29,
It reaches 30 and is slightly pressurized. The air outlet 36 of the air outlet 35 that communicates the pressurizing chambers 29 and 30 with the outside air is provided with a front pressurizing chamber pressure adjusting valve 36a and a rear pressurizing chamber pressure adjusting valve 36b, respectively. The pressure inside 29 and 30 can be adjusted independently. Next, the air in the pressurizing chambers 29 and 30 is
Part of the air outlet 37 with each adjusted pressure
The other air is discharged from the front and rear ends of the main shaft 2 to the outside air through the front bearing 3, the rear bearing 4, the front labyrinth 22 and the rear labyrinth 24, respectively. When the air passes through the front bearing 3 and the rear bearing 4, the air absorbs heat from the bearing portion that is heated by rotational friction and cools it.
Further, the air that has taken the heat and passed through the bearing portion always flows to the outside air in the labyrinths 22 and 24, so that cutting oil and fine chips in the atmosphere pass through the labyrinths 22 and 24 and blower blades 25 and 26. Is prevented from entering. Furthermore, since the strength of the air flow discharged to the outside air through the labyrinths 22 and 24 is independently controlled by the pressurizing chamber pressure adjusting valves 36a and 36b, the air flow is reduced to the blower blades 25 and 2.
The high-quality grease used in 6 is not discharged from the labyrinths 22 and 24.

The air amount and the air pressure of the air blown from the first space portion 28, which is a negative pressure chamber, to the pressurizing chambers 29, 30 by the blower blades increase in accordance with the rotation speed of the blower blades. In other words,
The amount of air increases in proportion to the rotation speed of the blower blades, and the air pressure increases in proportion to the square of the rotation speed of the blower blades.

Normally, under the condition that the size and rotation speed of the blower blades are the same, the amount of air blown and the air pressure increase as the number of blades increases. Furthermore, the steeper the blade mounting angle, that is, the larger the mounting angle α, the more the air amount and the air pressure increase. Therefore, the blower front blades 25
If the number of the fan rear blades 26 and the mounting angle are different as described above, the proportion of the flow divided from the first space portion 28, which is a negative pressure chamber, to the front pressure chamber 29 and the rear pressure chamber 30, Since the flow rate and the pressure are different, the values of the optimum conditions can be set for the bearing states of the front bearing 3 and the rear bearing 4. As for the material of the blades, a plastic molded product or the like may be integrally formed with the sleeve portion 42 fitted to the intermediate portion 13 of the main shaft 2 and fixed to the main shaft 2 by a fixing means 41 such as a screw. The heat dissipation effect is better if it is made of a metal with high conductivity such as aluminum or copper.

Although the embodiment of the headstock of the machine tool according to the present invention has been described in detail above, it is needless to say that the present invention is not limited to the above embodiment. That is, in the above embodiment, an axial blower is incorporated as a blower in the drawings, but the blower is not necessarily limited to the axial blower, and, for example, a centrifugal blower or the like can be applied. is there. Further, in the figure, the one in which the air suction path is provided is shown, but it is not necessarily limited to one location,
Needless to say, it may be configured to be provided at an appropriate place or for both bearings. Further, the spindle is not limited to the cutting tool, the workpiece mounting chuck, etc., and it goes without saying that a workpiece can be mounted.

〔The invention's effect〕

Since the present invention is configured as described above, it has the following effects. That is, in a machine tool, heat that is disliked in precision turning is generated by a bearing that rotationally supports the main shaft, but by passing the cooling air sent by the blower blades attached to this main shaft through a bearing that is a heat generation source, It can be cooled efficiently near the source of heat. Further, since the supply air pressure and the supply air amount sent by the blower blades change with the forward characteristic with respect to the rotational speed of the main shaft, the supply air pressure and the supply air pressure increase as the rotational speed at which the rotational frictional heat is generated is large. Since the air flow rate is increased, the amount of rotational frictional heat generated can be appropriately accommodated. Moreover, since the cooling air is supplied only by using a part of the rotational driving force of the main shaft, it is not necessary to prepare an external air supply device only for supplying the cooling air. Further, since a filter is provided in the air inflow path, it is possible to prevent foreign matter such as oil content and fine cutting dust from entering the intake air in the atmosphere of the machine tool. In addition, the amount of air discharged through the labyrinth at the front and rear ends can be controlled independently by the front and rear pressurization chamber pressure control valves according to each bearing state and labyrinth state, so high-quality grease applied to the bearings from these labyrinths It is also possible to prevent unnecessary exposure of the grease and maintain the quality of this high quality grease.

[Brief description of drawings]

1 is a sectional view showing an embodiment of a headstock of a machine tool according to the present invention, FIG. 2 is a front view of blower blades in the headstock of the machine tool of FIG. 1, and FIG. 3 is a line III of FIG. It is the side view seen from the direction of -III. 1 ... Headstock, 2 ... Spindle, 3 ... Front bearing, 4 ... Rear bearing, 5 ... Spindle casing, 22 ... Front labyrinth, 24
…… Rear labyrinth, 25 …… Blower front blade, 26 …… Blower rear blade, 27 …… Gap, 28 …… First space (negative pressure chamber),
29,30 …… Second space (front pressure chamber, rear pressure chamber), 31,37…
… Air suction passage, 32 …… Air inlet, 33,38 …… Filter, 34,39 …… One-way valve, 35 …… Air discharge passage, 36 …… Air discharge outlet, 36a …… Adjust pressure of front pressurizing chamber Valve, 36b ... rear pressure chamber pressure control valve, 40 ... blower.

Claims (6)

[Claims] 1. A main shaft is rotatably supported by a main shaft casing via a pair of bearings, a blower is attached to the main shaft between the bearings, and the blower sucks air through an air suction passage to blow the air to the bearing. At the same time, the headstock of a machine tool is characterized in that an air discharge passage having a pressure adjusting valve is formed in the main shaft casing at a portion between the blower and the bearing to adjust an air flow rate to the bearing. 2. The machine tool according to claim 1, wherein the air suction passage is formed in the main shaft casing, and the air suction passage is provided with a filter and a one-way valve. Headstock. 3. The main spindle of a machine tool according to claim 1, wherein the blower has a pair of blower blades mounted at opposite mounting angles with respect to a central axis of rotation of the main spindle. Stand. 4. The air suction passage is formed so as to penetrate the main shaft casing in the radial direction and to communicate with a first space portion formed between the blades surrounded by the main shaft and the main shaft casing. The headstock of a machine tool according to claim 3, wherein the headstock is a machine tool. 5. The air suction passage is formed so as to penetrate the main shaft and communicate with a first space portion formed between the blades surrounded by the main shaft and the main shaft casing. A headstock of a machine tool according to claim 3. 6. The headstock of a machine tool according to claim 1, wherein a labyrinth is formed between the main shaft and the main shaft casing on the axially outer side of the bearing.