JPH0811349B2 - Machine tool with spindle structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a machine tool having a spindle structure having a rotary shaft to which a tool for processing a workpiece is attached.

[Prior Art] A first example of a conventional spindle structure has a structure shown in FIGS. Explaining the conventional spindle structure with both figures, the spindle 10
1 is a rotary shaft 10 having a tool 107 for processing a workpiece at its tip
The bearing 103 supports the bearing 2, the quill 104 holds the bearing 103, and the housing 105 holds the quill 104. When the rotating shaft 102 is rotated by a motor or the like via the pulley 106, the bearing ball 119 and the inner and outer rings 120, 11 shown in FIG.
Friction heat is generated by friction with 8. This friction heat is generated by the rotating shaft 102.
The higher the rotational speed and the higher the load, the higher the temperature of the entire main spindle structure 101 due to heat transfer and the more it expands, resulting in a machining error with respect to the desired machined shape of the workpiece.

In order to prevent this processing error, oil supply passage 108a is added to quill 104.
.About.108e (108c is located at a position out of phase with 108b). A mixing valve 1 supplied from a pump 114 to these oil supply passages 108 and further having a metering piston type distributor 115.
Lubricating oil discharged from 21 in a fixed amount (hereinafter also referred to as oil)
And the compressed air that has passed through the filter 113 are continuously supplied to lubricate and cool the bearing 103. This results in oil bearing 1
It absorbs the heat generated by 03. After absorbing the heat, the oil passes from the bearing outlets 110a to 110e in the lower part of FIG.

The above cooling system is a cooling method that uses the sensible heat of oil, and the cooling efficiency is poor because the amount of heat transfer is extremely small compared to latent heat, and the oil is about 1000 times more viscous at room temperature than water and air. The rotation of the shaft 102 stirs to generate stirring heat, and the oil discharged from the main shaft structure 101 deteriorates the surrounding environment. Furthermore, the units 112 and 121 for supplying air and oil are required, which causes a problem of high cost.

Another main spindle structure 201 having a conventional cooling system is a bearing 203, a bearing 20 for supporting a rotary shaft 202 as shown in FIG.
It is configured by a quill 204 holding 3 and a housing 205 holding the quill 204. Here, regarding the relationship between the spindle structure 201 and the workpiece 230 shown in FIG. 6, the feed screw 229 is first rotated by the motor 225 or the like. This rotation is housing 2
The main shaft structure 201 is guided by the linear guides 226, 227 provided in the housing 205 by the support member 228 connected and fixed to 05, and the main shaft structure 201 moves linearly in the vertical direction with respect to the workpiece 230, and is installed at the tip of the rotary shaft 202. The workpiece 230 is processed by the tool 207. The above-mentioned movement can also be performed by a rack and pinion mechanism or the like.

When the rotating shaft 202 rotates at high speed, the amount of heat generated increases in proportion to this, and this heat generation causes the rotating shaft 202 and the housing 205 to rotate.
Is heated and thermally expanded, which affects the processing accuracy of the workpiece 230. That is, the protrusion amount L ₁ from the support member 228 to the front end of the housing 205 increases by Δ | due to the temperature rise of the housing 205, and the core height H of the linear guides 226 and 227 from the housing 205 support portion to the center of the main shaft structure 201 is increased. The temperature of the housing 205 increases by Δh, and if the temperature difference (t ₂ −t ₁ ) of the housing 205 on which the linear guides 226 and 227 are supported increases, the displacement Δθ increases, and so on. There is a processing error for the processing shape required for.

Therefore, as shown in FIG. 7, in order to suppress the temperature rise and expansion of the housing 205 and the like due to the heat generation of the bearing 203 due to the rotation of the rotating shaft 202, a lead groove 208 is provided on the outer periphery of the quill 204 to form a cooling jacket portion, A medium 210 such as oil is made to flow in or a heat pipe is incorporated, the heat amount from the bearing 203 is absorbed when the oil 210 or the like passes through the jacket, the oil 210 after absorbing heat moves to the outside, and the liquid tank of the cooling unit 209. 211 and further to the cooler 213 by the circulation pump 212. In the cooler 213, the chlorofluorocarbon gas 218 is compressed by the compressor 214 and becomes high-temperature high-pressure gas. Freon 218, which has become high-temperature and high-pressure gas, is transported to condenser 215,
The cooling fan 216 comes into contact with low-temperature air to radiate heat and liquefy. The chlorofluorocarbon 218 liquefied by the condenser 215 enters the expansion valve 217, becomes a low temperature low pressure liquid, and is conveyed to the cooler 213. This low-temperature low-pressure liquid comes into contact with the medium (oil) 210 that has absorbed heat from the bearing 203, the Freon 218 is vaporized, and the compressor is again compressed.
Transported to 214. Medium 2 after heat absorption by this heat transfer cycle
10 is cooled by the cooler 213, returned to the liquid tank 211, and sent again to the spindle jacket by the pressure pump.

Considering only the cooling jacket portion, the above system cools the spindle structure 201 by utilizing the sensible heat of oil, and therefore has the same drawbacks as the spindle structure 101 of the first example. The equipment becomes larger and the cooling jacket 208
Since it is a lead groove, the pressure loss increases and the cooling effect decreases. Further, since the cooling jacket 208 is provided on the outer peripheral portion of the quill 204, the diameter D of the housing 205 is larger than that of a spindle that does not have a cooling jacket and has a low rotation speed and a low load.
Along with this, the housing 205 that supports the linear guides 226 and 227.
The slider width B (FIG. 8) also becomes large, and the entire main spindle structure 201 becomes large. Therefore, there is a problem that the inertia of the main shaft portion that performs linear movement becomes large, the load on the drive motor becomes large, and the cycle time is affected.

[Problems to be Solved by the Invention] An object of the present invention is to provide a machine tool that has high cooling efficiency, can withstand high speed rotation and heavy load, and is small in size and low in cost.

[Technical Means for Solving the Problems] The present invention as set forth in claim 1 made to solve the above problems, includes a rotary shaft having a tool for processing a workpiece attached to a tip thereof, A machine tool having a spindle structure having a quill that rotatably supports the rotating shaft via a bearing, and a housing that is fitted on the quill and holds the quill, wherein a quill is provided with a liquid mist. An air passage for circulating the containing air is provided, and the air passage has a supply port and an outlet for the air containing the liquid mist, and the supply port further includes an air containing a water mist as the liquid mist. The main point is a machine tool having a spindle structure characterized by being in communication with a supply device for supplying.

The present invention according to claim 2 provides a rotating shaft having a tool for processing a workpiece attached to a tip thereof, a quill rotatably supporting the rotating shaft via a bearing, and the quill. A machine tool having a main shaft structure having an externally fitted housing for holding the quill, and a circle arranged on the outer peripheral surface of the quill, on which the housing is externally fitted, near both ends of the outer peripheral surface. A circular groove in the circumferential direction and a plurality of linear grooves that are formed in the axial direction of the quill and communicate with both of the circular grooves and are evenly distributed in the circumferential direction on the outer peripheral surface are provided. In the surface, the portion between the linear grooves is a land portion having a minute gap between the linear groove and the inner surface of the housing. Further, one of the circular grooves is supplied with air containing water mist from the outside. Together with the above It is that from the other circular groove configured to discharge the air to the outside, a machine tool having a spindle structure characterized by the subject matter.

[Operation] In the machine tool having the spindle structure according to claim 1 configured as described above, an air passage for circulating air containing liquid mist in a quill that supports a rotating shaft via a bearing. Is provided, and the air containing the water mist is supplied from the supply device to the supply port of the air passage.
Then, the air is discharged to the outside from the outlet of the air passage after flowing through the air passage.

Here, when the air containing the water mist from the supply device passes through the air passage of the quill, the water mist in the air adheres to the passage surface of the quill. Then, the water mist adhering to the passage surface is evaporated by the heat generated by the rotation of the rotating shaft, and the moisture-laden air is discharged to the outside from the outlet of the air passage. That is, in the machine tool according to claim 1, the entire spindle structure is cooled by the latent heat of vaporization (vaporization heat) of the water mist via the quill,
As a result, deformation of the spindle structure due to heat is prevented, and the processing accuracy of the workpiece is improved.

As described above, according to the machine tool having the spindle structure according to the first aspect, since the spindle structure is cooled by the latent heat of vaporization of the water mist, compared with the conventional cooling by the sensible heat method. Since the amount of heat transfer is greatly improved and the cooling efficiency is extremely high, it becomes possible to endure high rotation and high load. Further, since the viscosity of the air containing the water mist is very low, the diameter of the air passage can be set small, and by extension, the outer diameter of the quill and the housing can be made small to downsize the main shaft structure. .

Moreover, since the cooling is performed by the air containing the water mist, the structure of the supply device can be simplified, and the discharged oil like the conventional device using oil is collected to prevent the environmental deterioration. A recovery device for preventing the need is eliminated, and the entire machine tool can be downsized and the cost can be reduced.

Next, in the machine tool provided with the spindle structure according to claim 2, the outer surface of the quill in which the housing is fitted is
Circular circular grooves arranged in the vicinity of both ends of the outer peripheral surface, respectively, and communicated with both circular grooves formed in the axial direction of the quill,
The outer peripheral surface is provided with a plurality of linear grooves that are evenly distributed in the circumferential direction, and the portion between the linear grooves on the outer peripheral surface is a minute gap with the inner surface of the housing. Has become a land portion. Then, air containing water mist is supplied to one of the two circular grooves from the outside, and the air is discharged to the outside from the other of the two circular grooves.

That is, in the machine tool according to claim 2, in order to circulate the air containing the water mist by the two circular grooves formed on the outer peripheral surface of the quill and the plurality of linear grooves connecting the both circular grooves. The air passage of is formed. And the air containing the water mist supplied to one of the circular grooves,
It passes through each of the plurality of straight grooves, reaches the other circular groove, and is discharged to the outside from the circular groove. At this time, the water mist invades a minute gap between the land portion between the respective straight grooves and the inner surface of the housing, and the water mist that has entered forms a water film to seal the space between the adjacent straight grooves. Therefore, the distribution of the water mist between the linear grooves is made uniform.

Also in the machine tool provided with the spindle structure according to claim 2, as in the machine tool according to claim 1, water mist in the supplied air adheres to the circular groove and the linear groove,
Due to the latent heat of vaporization when the attached water mist evaporates,
The entire spindle structure is cooled via the quill.

Therefore, according to the machine tool having the spindle structure described in claim 2, the cooling efficiency can be made extremely high, and the air containing water mist can be used just like the machine tool described in claim 1. In addition to simplifying the configuration of the supply device of, the need for a collecting device that collects the discharged oil to prevent environmental deterioration like the conventional device using oil is unnecessary, so the entire machine tool The size and cost can be reduced.

Moreover, according to the machine tool having the spindle structure of the second aspect, the water mist can be uniformly distributed on the outer peripheral surface of the quill, and the quill can be cooled uniformly in the axial direction and the radial direction. . In addition, since the viscosity of air containing water mist is very low, the depth of circular grooves and straight grooves can be set to a small value, which in turn reduces the outer diameter of the quill and housing to reduce the spindle structure. can do. Furthermore, by simply forming a circular groove in the circumferential direction and a linear groove in the axial direction on the outer peripheral surface of the quill, an air passage for circulating air containing water mist can be formed, so that the main spindle structure can be simplified. Can be manufactured.

Embodiments The present invention will be described below with reference to the drawings illustrating embodiments. FIG. 1 shows the first embodiment. In the figure, the driving force of a motor (not shown) is transmitted to the rotary shaft 2 via a power transmission member (eg, gear, pulley, etc.) 6 fixed to the outer periphery of the rear end portion (right end portion in FIG. 1) of the main shaft structure 1. To be done. The rotating shaft 2 is rotatably supported by a bearing 3, and the bearing 3 is supported by a quill 4. The quill 4 has five mist supply ports 9 which will be described later and are out of phase with each other, and five mist supply paths 8a communicating therewith.
8e, one discharge passage 11 and one discharge port 11a are provided. The quill 4 is held by a housing 5, and a two-fluid mixing nozzle 12 is installed in the housing 5 near the mist supply port 9. In FIG. 1, reference numeral 7 is a tool attached to the tip of the rotary shaft 2 for processing a workpiece.

Air supplied from a pressurized air source (not shown), passed through the filter 16, and a small amount of water 15 sent from the water tank 14 via the pump 13 are mixed in the two-fluid mixing nozzle 12 to form a mist (spray) form. Next, the fog supply port 9 and fog supply paths 8a to 8e (8c is 8b
(Not shown in the figure because the phase is different) and is injected into the bearing 3. At this time, water mist (hereinafter simply referred to as mist) is applied to the bearing 3.
Although mist adheres, this mist is generated by the rotation of the rotary shaft 2 and the bearing 3
Evaporates due to the exothermic heat. The air that is moistened by evaporation passes through the spindle outlets 10a to 10e and is sent to the outlet passage 11 where the outlet 11
Emitted from a. Therefore, the amount of heat generated in the bearing 3 is absorbed by the latent heat of vaporization of the mist and carried to the outside. For this reason, the heat transfer is 100 times or more compared to the cooling by the conventional sensible heat method, and the cooling efficiency becomes extremely high. Further, since the viscosity of water and air is lower than that of cooling by oil, the heat of stirring is low, and the diameters of the fog passages 8a to 8e can be set to be small. The main shaft structure 1 can be downsized by reducing the diameter.

Further, according to the first embodiment, since the cooling is performed by the air containing the water mist, the system for supplying the mist becomes a very simple system and the discharge is performed like the conventional method using oil. Since it is not necessary to collect the collected oil, it is possible to reduce the size and cost of the machine tool having high cooling efficiency and capable of withstanding high rotation and high load.
Even if the air discharged from the discharge port 11a contains mist, it is very easy to use a water-soluble coolant oil (working oil) when processing the work piece. Environmental pollution can be prevented.

In the above configuration, the five mist supply ports 9 and the mist supply paths 8a to 8e
The number of bearings 3 is provided, but this is because it is matched with the number of bearings 3, and these numbers are arbitrary.

Although the power transmission member 6 fixed to the rotary shaft 2 is used when transmitting the rotational force to the rotary shaft 2, a method of rotating the rotary shaft 2 by a built-in motor or a direct connection between the main power source and the rotary shaft 2 is used. Then, the rotary shaft 2 may be directly rotated.

If water 15 which is one of the cooling media is mixed with rust preventive oil and put in the water tank 14, the bearing 3, the fog supply passage 8 and the discharge port 10 can be rust prevented and the bearing 3 is lubricated. Has the effect of

2 and 3 show a second embodiment. In the spindle structure 21 shown in FIG. 2 (a), the driving force of the motor (not shown) is the rotating shaft.
22 Pulley fixed to the outer periphery of the rear end (right end in Fig. 2)
It is transmitted to the rotary shaft 22 via 26. The rotating shaft 22 is supported by a bearing 23, which is held by a quill 24. On the outer periphery of the quill 24, there are provided multiple rows of axial linear grooves 28 arranged at equal intervals in the circumferential direction of the quill 24, and further circumferential grooves 29 and 30 are provided at both ends of the linear groove 28. Has been. The two-fluid mixing valve 31 installed in the vicinity of the housing 25 mixes the air from the filter 37 with a small amount of water sent from the water tank 33 via the pump 36 to form a mist (spray) on the tool 27 side. Circumferential groove (hereafter called circular header) 29
It is jetted so as to generate a swirling flow in the tangential direction as shown in FIG. At this time, the flow velocity of the mist sent to the circular header 29 is quite high (1.5 m / sec), so the circular header 29
Pressure distribution and mist distribution are uniform, and circular header
The mist is evenly distributed from 29 to the axial groove portion 28. The mist adhering to the linear groove 28 on the outer peripheral surface of the quill 24 is evaporated by the heat generation of the bearing 23 accompanying the rotation of the rotary shaft 22, and the moist air due to the evaporation is the circular header 29.
Via the circumferential groove 30 on the side opposite the
Is discharged to the outside. Therefore, the amount of heat generated in the bearing 23 is absorbed by the latent heat of vaporization of the mist and carried to the outside. Third
As shown in FIGS. (A) and (B), the axial linear groove 28 is chamfered to form a substantially semi-cylindrical groove, and the land portions 32 are evenly distributed in the circumferential direction of the quill 24. There is a minute gap between the land portion 32 and the inner surface of the housing 25, and the mist enters there. The invaded mist forms a film in the above-mentioned gap, acts as a seal between the adjacent groove portions, and makes the distribution of the mist between the groove portions more uniform. Further, even if the mist excessively penetrates into the above-mentioned gap, the water flows into the groove portion and becomes the latent heat of vaporization to exert the cooling effect. If only the groove portion not having the land portion 32 and the groove portion 28, that is, if it is a cylindrical cooling groove, it has no header, the mist distribution is non-uniform, and a cooling error (variation) occurs in the axial direction and the radial direction, resulting in a temperature distribution. It becomes uneven.

Since the present embodiment has the circular header 29, the diameter groove 28, and the land portion 32, the sealability with the adjacent groove portion is improved, and a high-speed swirling flow is generated to make the mist distribution uniform and stabilize the cooling of the spindle structure. Let

Next, the depth of the linear groove 28 will be described. The quill 24 is fitted into the housing 25, and the fitting portions are the front and rear portions 34 and 35 of the quill 24, and an ordinary "sunk" is provided at the center thereof. In the present embodiment, the depth of the slime is the housing
The small clearance between the inner diameter of 25 and the outer diameter of quill 24 is about 0.2-1.0 mm. This is quill 24 and housing 25
It is provided in order to maintain the processing accuracy of the fitting portions 34 and 35 with and to facilitate the assembling work at the time of fitting. The clearance is made equal to the depth of the linear groove 28, and the circular header 29, the linear groove 28, and the land portion 32 are used for cooling using the latent heat. With conventional cooling using oil, it is not possible to secure the required flow rate of oil at the depth of the above groove, but if low-viscosity air is used, the flow rate of air can be secured about 10,000 times the flow rate of oil, so It becomes possible to cool the mist by using. By using this slime as a cooling jacket, the outer diameters of the quill 24 and the housing 25 are smaller and the weight is halved compared to the conventional oil cooling, and the slider width which is the guide portion of the linear guide is also small accordingly. As a result, the overall spindle structure becomes smaller, the load inertia on the motor that moves the workpiece linearly is halved, and the acceleration / deceleration time of the motor accompanying the load reduction is 1
It is shortened to / 2, and it has an excellent effect that the cycle time is shortened (speeded up).

 Next, a specific example of the above configuration will be described.

Bearing 23 accompanying rotation of rotary shaft 22 of main shaft structure 21 of the present embodiment
The calorific value Q _h of the rotating shaft diameter d = φ50 mm, shaft rotation speed N = 15000 r
When pm, Q _h = 172Kcal in the groove in the heat balance condition Qh = Qc of the cooling heat Q _C of the latent heat of vaporization (in the cooling jacket) absolute pressure P = 1.1Kgf / cm ^2, air flow rate W = 130Nl / min ( Factory air dew point -20 ° C), water injection amount V = 4 g / min, groove depth = 0.5 mm to cool the main shaft.

As a result, the amount of temperature rise from room temperature of the spindle structure could be suppressed to 8 ° C or less. This embodiment has a structure including a circular header, a straight multi-row groove, and a land portion instead of the conventional lead groove structure, so that there is no pressure loss.
This is because the mist distribution becomes uniform, so that the temperature distribution of the main shaft structure becomes uniform and stable cooling can be performed. That is, by changing the refrigerant from oil to air of low viscosity, 10,000
The double flow rate can be secured, and more than 100 times the heat can be transferred by changing the cooling method from sensible heat to latent heat of evaporation, so cooling can be performed with higher efficiency than the conventional structure, and since the slime is used for the jacket The spindle structure becomes smaller.

[Effects] As described in detail above, according to the machine tool having the spindle structure according to the first aspect, the cooling efficiency is extremely high, and thus it is possible to endure high rotation and high load. And
Since the spindle structure and the entire machine tool can be downsized, it can be installed in a narrow space, and the cost can be reduced.

According to the machine tool having the spindle structure according to the second aspect, in addition to the above effects, the quill supporting the rotary shaft can be further uniformly cooled in the axial direction and the radial direction, so that the spindle structure is stable. And can be cooled. And further,
Since the air passage for circulating the air containing the water mist can be formed only by forming the circular groove in the circumferential direction and the linear groove in the axial direction on the outer peripheral surface of the quill, the manufacturing is very simple.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of the first embodiment. Figure 2 (a)
Shows a vertical sectional front view of the second embodiment. Figure 2 (b) is the second
The perspective view of the principal part of FIG. FIG. 3A shows a sectional view taken along the line AA of FIG. FIG. 3B shows a perspective view of a part of FIG. FIG. 4 shows a front sectional view of an example of a conventional spindle structure including a cooling device. FIG. 5 shows an enlarged front sectional view of a portion A in FIG. FIG. 6 is a front view showing the state of displacement of the tool during operation of the conventional spindle structure (spindle structure of FIG. 7). FIG. 7 is a front sectional view of a conventional spindle structure, which is a different example from FIG. 4, including a cooling device. 8th
The figure shows a side view of FIG. 1, 21 …… Spindle structure 2,22 …… Rotary shaft 3,23 …… Bearing 4,24 …… Quill 5,25 …… Housing 7,27 …… Tool 8 …… Mist supply path (air passage) 9 ・ ・ ・… Mist supply port (supply port) 11a… Discharge port 12 …… Two-fluid mixing nozzle (air supply device including liquid mist) 28 …… Straight groove (air passage) 29 …… Circular groove (air passage) 30 …… Circumferential groove (air passage) 31 …… Two fluid mixing valve (air supply device including liquid mist)

Claims (2)

[Claims] 1. A rotating shaft having a tool for processing a work piece attached to a tip thereof, a quill rotatably supporting the rotating shaft via a bearing, and a quill fitted to the quill so as to fit the quill. A machine tool having a main shaft structure having a housing for holding the quill, the quill is provided with an air passage for circulating air containing liquid mist, and the air passage supplies the air containing the liquid mist. A machine tool having a spindle structure, comprising a port and a discharge port, wherein the supply port communicates with a supply device that supplies air containing water mist as the liquid mist. 2. A rotary shaft having a tool for processing a work piece attached to a tip thereof, a quill rotatably supporting the rotary shaft via a bearing, and a quill externally fitted to the quill. In a machine tool having a main shaft structure having a housing for holding, the outer peripheral surface of the quill to which the housing is fitted,
Circular circular grooves arranged near both ends of the outer peripheral surface, respectively, are formed in the axial direction of the quill and communicate with both circular grooves, and are evenly distributed in the circumferential direction on the outer peripheral surface. A plurality of linear grooves are provided, and a portion between the linear grooves on the outer peripheral surface is a land portion having a minute gap with the inner surface of the housing. A machine tool having a spindle structure, characterized in that it is configured such that air containing water mist is supplied to one of the two from outside and the air is discharged to the outside from the other of the circular grooves.