JPH03196941A - Spindle structure - Google Patents

Abstract

PURPOSE:To keep off any thermal deformation in a spindle structure by installing a passage for air, containing a water mist, in a quill supporting a turning shaft via a bearing, and cooling the whole spindle structure through a latent heat of vaporization in this water mist, in the spindle structure of a machine tool. CONSTITUTION:Driving force of a motor is transmitted to a turning shaft 2 via a rear end member of a spindle structure 1, and this turning shaft 2 is supported by a quill 4 via a bearing 3. This quill 4 is supported by a housing 5, and a binary-fluid mixing nozzle 12 is set up in this housing 5 in and around a mist feeding port 9. The water mist is jetted into the bearing 3 after passing through this mist feeding port 9 and each of mist feeding passages 81- 8e. At this time, the water mist is stuck to the bearing 3, but this mist is vaporized by generation of heat by rotation of the turning shaft 2. Air contained with humidity by vaporization passes through each of main exhaust ports 10a-10e and discharged out of an exhaust port 11a after being fed to an exhaust passage 11. Consequently, a quantity of heat generated in the bearing 3 is absorbed by a latent heat of vaporization in the mist and carried to the outside. Thus, cooling efficiency is extremely enhanced.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to the structure of a main shaft of a machine tool.

Prior Art] A first example of a conventional main shaft structure has the structure shown in FIG. 4.5. To explain the conventional spindle structure using both figures, the spindle 10
Reference numeral 1 denotes a bearing 103 that supports a rotating shaft 102 having a tool 107 at its tip for processing a workpiece, a quill 104 that holds the bearing 103, and a housing 1 that holds the quill 104.
05. When the rotating shaft 102 is rotated by a motor or the like via the pulley 106, frictional heat is generated due to friction between the bearing ball 119 shown in FIG. 5 and the inner and outer rings 120 and 118 of the bearing. This frictional heat increases as the rotational speed and load of the rotating shaft 102 increases, so the temperature of the entire main shaft structure 101 rises due to heat transfer, and since engraving occurs, machining errors occur in the desired machined shape of the workpiece. .

In order to prevent this machining error, an oil supply path 10 is provided in the quill 104.
8a to 108e (108C is located out of phase with 108b). These oil supply paths 10B are supplied with oil from a pump 114, and are further supplied with a metering piston type distributor 115.
The bearing 103 is lubricated and cooled by continuously supplying a fixed amount of lubricating oil (hereinafter also referred to as oil) discharged from a mixing valve 121 having a filter 113 and compressed air that has passed through a filter 113. As a result, the oil absorbs the heat generated in the bearing 103. After absorbing heat, the oil passes through the discharge passage 111 from the bearing discharge ports 110a to 110e in the lower part of FIG.
It is discharged from 11a.

The above cooling system is a cooling method that uses the sensible heat of oil, and the amount of heat transfer is extremely small compared to latent heat, resulting in poor cooling efficiency.Also, oil is about 1000 times more viscous than water or air at room temperature, so it rotates. The oil that is stirred by the rotation of the shaft 102 and generates stirring heat and discharged from the main shaft structure 101 worsens the surrounding environment. Furthermore, units 112 and 121 for supplying air and oil are required, resulting in problems such as increased cost.

Another main shaft structure 201 having a conventional cooling system includes a bearing 203 supporting a rotating shaft 202, as shown in FIG.
It is composed of a quill 204 that holds a bearing 203, a housing 205 that holds the quill 204, and the like. Here, regarding the relationship between the main shaft structure 201 and the workpiece 230 shown in FIG. 6, first, the feed screw 229 is rotated by the motor 225 or the like.

This rotation is controlled by the linear guide 2 provided in the housing 205 by a supporting member 228 connected and fixed to the housing 205.
26 and 227, the spindle structure 201 linearly moves perpendicularly to the workpiece 230, and the workpiece 230 is machined by the tool 207 installed at the tip of the rotary shaft 202. Note that the above movement is also possible by a rack-and-binion mechanism or the like.

When the rotating shaft 202 rotates at a 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 heat up and perform thermal engraving, which affects the processing accuracy of the workpiece 230. That is, from the support member 228 to the housing 2
05 The protrusion amount L1 to the front end increases by Δ1 due to the temperature increase of the housing 205, and the center height of the linear guides 226 and 227 from the housing 205 support part to the center of the main shaft structure 201 increases by Δh due to the temperature increase of the housing 205. housing 20 with increased linear guides 226, 227 supported;
If the temperature difference (t2-11) of 5 increases, the displacement Δθ increases, and a machining error occurs in the machining shape required for the workpiece 230.

Therefore, as shown in FIG. 7, a lead groove 208 is provided on the outer periphery of the quill 204 as a cooling jacket part in order to suppress the temperature rise and engraving of the housing 205 etc. due to the heat generated by the bearing 203 when the rotating shaft 202 rotates. , a medium 210 such as oil is introduced or a heat pipe is incorporated, and when the oil 210 and the like passes through the jacket, it absorbs the amount of heat from the bearing 203. After absorbing heat, the oil 210 moves to the outside, and the liquid in the cooling unit 209 is absorbed. It is sent to the tank 211 and further to the cooler 213 by the circulation pump 212.

In the cooler 213, the fluorocarbon gas 218 is compressed by the compressor 214 to become a high-temperature, high-pressure gas. Freon 218, which has become a high-temperature, high-pressure gas, is transported to a condenser 215, where it comes into contact with low-temperature air produced by a cooling fan 216, radiates heat, and liquefies. The fluorocarbon 218 liquefied by the condenser 215 enters the engraving valve 217 and becomes a low-temperature, low-pressure liquid and is conveyed to the cooler 213. This low-temperature, low-pressure liquid and the aforementioned bearing 203
The medium (oil) 210 that has absorbed heat from the fluorocarbon 2 comes into contact with the
18 is vaporized and transported to the compressor 214 again. Through this heat transfer cycle, the medium 210 after absorbing heat is transferred to the cooler 213.
The liquid is cooled by the water, returned to the liquid tank 211, and sent to the main shaft jacket again by the pressure pump.

Considering only the cooling jacket portion, the above system cools the main shaft structure 201 using the sensible heat of the oil, so it has the same drawbacks as the main shaft structure 101 of the first example. Furthermore, the equipment has become larger and cooling jacket 2 has been added.
Since 0B is a lead groove, pressure loss increases and the cooling effect decreases.

Furthermore, since a cooling jacket 208 is provided on the outer circumference of the quill 204, the diameter of the housing 205 is larger than that of a low-speed rotating, low-load main shaft that does not have a cooling jacket. The slider width B (FIG. 8) of 205 also increases, and the entire main shaft structure 201 becomes large. For this reason, the inertia of the main shaft portion that performs linear motion increases, which increases the load on the drive motor, causing problems such as affecting cycle time.

[Problem to be solved by the invention] This invention has high cooling efficiency, can withstand high speed rotation and high load,
The objective is to provide a spindle structure that is also small and low cost.

[Technical Means for Solving the Problems] In order to solve the above problems, the present invention includes a rotating shaft supported by a quill via a bearing, a housing fitted onto the quill, and an air containing water mist installed in the quill. A passageway is provided,
The air passage has a supply port and a discharge port for air containing liquid mist, and the supply port is configured to communicate with a supply device for air containing liquid mist.

[Operation] When air containing liquid mist passes through the air passage on the outer circumferential surface of the quill, the mist adheres to the outer surface of the quill. The mist attached to the outer surface of the quill is evaporated by the heat generated in the spindle structure by the high-speed rotation of the rotating shaft, and the latent heat of evaporation cools the entire spindle structure through the quill to prevent the spindle structure from deforming due to heat, and the workpiece is Improve machining accuracy for

[Examples] The present invention will be described below with reference to drawings showing examples. 1st
The figure shows a first embodiment. In the figure, the driving force of the motor (not shown) is applied to the rear end of the main shaft structure 1 (the right end in Figure 1).
The power is transmitted to the rotating shaft 2 via a power transmission member (for example, a gear, a pulley, etc.) fixed to the outer periphery. 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 5 out of phase with each other, which will be described later.
five mist supply ports 9 and five mist supply paths 8a to 8 communicating therewith.
e, one discharge passage 11, and one discharge port 11a are provided. The quill 4 is held in the housing 5,
A two-fluid mixing nozzle 12 is installed in the housing 5 near the mist supply port 9.
is installed.

Air supplied from a pressurized air source (not shown) and passed through a filter 16 and a small amount of water 15 sent from a water tank 14 via a pump 13 are mixed in a two-fluid mixing nozzle 12 to form a mist (spray). Therefore, the mist supply port 9, the mist supply path 8a~
8e (8C is not shown because the phase is different from 8b) and is injected into the bearing 3. At this time, water mist (hereinafter simply referred to as mist) adheres to the bearing 3, but this mist evaporates due to the heat generated by the bearing 3 due to the rotation of the rotating shaft 2. Humid air due to evaporation passes through the spindle exhaust ports 108 to 10e, is sent to the exhaust path 11, and is discharged from the exhaust port 11a. Therefore, the amount of heat generated in the bearing 3 is absorbed by the latent heat of vaporization of the mist and transported to the outside. Therefore, the heat transfer is 100 times or more compared to the conventional cooling method, and the cooling efficiency is extremely high. Also, since water and air have lower viscosity than cooling with oil, the heat generated by stirring is also lower. Furthermore, even if the discharged air contains mist, environmental pollution will not be a problem if a water-soluble coolant oil is used. Further, the mist supply means can be a very simple system, and has many excellent effects such as being small, low cost, high speed, and capable of handling heavy loads.

In the above configuration, five mist supply ports 9 and mist supply paths 8a to 8 are provided.
e was provided because it matched the number of bearings 3,
These numbers are arbitrary.

Although the power transmission member 6 fixed to the rotating shaft 2 is used to transmit the rotational force to the rotating shaft 2, it is also possible to use a built-in motor to rotate the rotating shaft 2 or directly connect the main power source to the rotating shaft 2. Alternatively, the rotating shaft 2 may be directly rotated.

By mixing anti-rust oil with water 15, which is one of the cooling media, and placing it in the water tank 14, it is possible to prevent rust between the bearing 3, the mist supply path 8, and the discharge port 10, and to lubricate the bearing 3. It has the effect of

Figure 2.3 shows a second embodiment. In the main shaft structure 21 in FIG. 2(A), the driving force of a motor (not shown) is transmitted to the rotating shaft 22 via a pulley 26 fixed to the outer periphery of the rear end (right end in FIG. 2) of the rotating shaft 22. be done. The rotating shaft 22 is supported by a bearing 23, and the bearing 23 is held by a quill 24.

The outer periphery of the quill 24 is provided with multiple rows of axial straight grooves 28 arranged at equal pitches in the circumferential direction of the quill 24.
Additionally, circumferential grooves 29,30 are provided at both ends of the straight groove 28.
is provided. A two-fluid mixing valve 31 installed near 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 and forms a mist (spray) on the tool 27 side. The mist is ejected into the circumferential groove portion (hereinafter referred to as the circular header) 29 to generate a swirling flow in the tangential direction as shown in Fig. 2. At this time, the flow velocity of the mist sent to the circular header 29 is Because of the fairly high speed (1.5 m/5 eC), the pressure distribution and mist distribution in the circular header 29 are uniform, and the mist is also uniformly distributed from the circular header 29 to the axial groove portion 28. The mist adhering to the linear groove 28 on the outer peripheral surface of the quill 24 evaporates due to the heat generated by the bearing 23 as the rotating shaft 22 rotates.

Therefore, the amount of heat generated in the bearing 23 is absorbed by the latent heat of vaporization of the mist and transported to the outside. As shown in FIGS. 3(A) and 3(B), the axial straight 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, into which mist enters. The mist that has entered forms a film in the above-mentioned gap and acts as a seal between adjacent grooves, making the mist distribution between the grooves more uniform. Furthermore, even if the mist enters the gap in excess, water flows into the groove and becomes latent heat of evaporation, exerting a cooling effect. Moreover, if only the groove part does not have the configuration of the land part 32 and the groove part 28, that is, a cylindrical cooling groove, it will not have a header and the mist distribution will be uneven, causing cooling errors (variations) in the axial and radial directions, and the temperature distribution will change. becomes uneven.

This embodiment has a circular header 29, a straight groove 28, and a land portion 32.
This improves sealing performance with adjacent grooves, generates high-speed swirling flow, makes mist distribution uniform, and stabilizes cooling of the main shaft structure.

Next, the depth of the straight groove 28 will be explained. The quill 24 is fitted into the housing 25, and the fitting part is the quill 24.
It is part 34.35 of the front and rear ends of 4, and a normal ``sink'' is provided in the center. In this embodiment, the depth of the clearance is a minute clearance between the inner diameter of the housing 5 and the outer diameter of the quill 4, and is approximately 0.2 to 1.0 mm. This is Quill 2
4 and the housing 25 in order to maintain the machining accuracy of the fitting parts 34 and 35 and to facilitate the assembly at the time of fitting. This clearance and the depth of the linear groove 28 are made the same, and the configuration of the circular header 29, the linear groove 28, and the land portion 32 performs cooling using the latent heat described above. With conventional cooling using oil, it is not possible to secure the necessary oil flow rate with the groove depth described above, but if low viscosity air is used, the air flow rate can be secured approximately 10,000 times the oil flow rate, so the above gap can be achieved. Mist cooling is possible using By using this gap as a cooling jacket, the outer diameter of the quill 24 and housing 25 is smaller and the weight is halved compared to conventional oil cooling, and the width of the slider, which is the guide part of the linear guide, is also smaller. As a result, the entire spindle structure has become smaller, and the load inertia on the motor that performs linear motion on the workpiece is 172.
Therefore, the acceleration/deceleration time of the motor due to the load reduction is also shortened to 1/2, and there are excellent effects such as shortening (speeding up) the cycle time.

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

The heat generation amount Qh of the bearing 23 accompanying the rotation of the rotating shaft 22 of the main shaft structure 21 of this embodiment is the rotating shaft diameter d=φ50m1 shaft rotation speed N
=1500Orpm, Qh=172kcal
The amount of cooling heat of latent heat of vaporization is Q. Under the heat balance condition Qh=Qc, the absolute pressure inside the groove (inside the cooling jacket) p= 1.1kgf
The main shaft portion was cooled using air flow rate W = 13ON I/min (factory air dew point -20°C), water injection IV = 4q/min, and groove depth = 0.58.

As a result of the above, it was possible to suppress the temperature rise of the main shaft structure from room temperature to 8°C or less. This is because, instead of the conventional lead groove structure, this embodiment has a configuration consisting of a circular header, linear multi-row grooves, and a land part, so there is no pressure loss, and the mist distribution is uniform, so that the main axis This is because the temperature distribution of the structure becomes uniform and stable cooling can be performed. In other words, by replacing the refrigerant from oil to air with low viscosity,
It is possible to secure 0 times the flow rate, and by changing the cooling method from sensible heat to latent heat of vaporization, it is possible to transfer more than 100 times the heat, so it can be cooled with higher efficiency than the conventional structure, and the slack can be used as a jacket. Therefore, the main shaft structure becomes smaller.

Although water is used as the mist component in both of the above embodiments, the mist component is not limited to water, and other liquids with large latent heat of vaporization may be used.

[Effects] Since the main shaft structure of the present invention has the above configuration, it has the following excellent effects.

(a) The main shaft structure can withstand high speed rotation and high loads and has extremely high cooling efficiency.

(b) Since it is small, it can be installed even in a narrow space.

(c) Since the structure is simple, manufacturing is easy and the cost is low.

[Brief explanation of drawings]

FIG. 1 shows a longitudinal sectional front view of the first embodiment. Figure 2 (a)
shows a longitudinal sectional front view of the second embodiment. Figure 2 (b) is the second
A perspective view of the main part of Figure (A) is shown. FIG. 3(a) shows a sectional view taken along the line A--A in FIG. 2(a). FIG. 3(B) shows a perspective view of a part of FIG. 3(A). FIG. 4 shows a front sectional view of an example of a conventional main shaft structure including a cooling device. FIG. 5 shows an enlarged front sectional view of section A in FIG. 4. FIG. 6 is a front view showing the state of displacement of the tool during operation of the spindle structure of FIG. 4. FIG. 7 shows a front sectional view of a conventional main shaft structure including a cooling device, which is different from FIG. 4. FIG. 8 shows a side view of FIG. 7. 1.21...Main shaft structure 2.22...Rotating shaft 3.23...Bearing 4.24...Quill 5.25...Housing 8...Mist supply path (air passage) 9. ...Mist supply port (supply port) 11a...Discharge port 12...Two-fluid mixing nozzle (supply device for air containing liquid mist) 31...Two-fluid mixing valve (supply device for air containing liquid mist) )

Claims (5)

[Claims] (1) A rotating shaft is supported by a quill via a bearing, a housing is fitted onto the quill, an air passage containing liquid mist is provided in the quill, and this air passage is a supply port for air containing liquid mist. and a discharge port, the supply port communicating with an air supply device containing liquid mist. (2) Claim (1) characterized in that the liquid is water.
) Main shaft structure as described. (3) The above-mentioned air supply device containing liquid mist is comprised of a pressurized air supply mechanism, a liquid supply mechanism, and a mechanism for mixing air and liquid.
1) Main shaft structure described. (4) A claim characterized in that the passage for the air containing the liquid mist comprises a mist supply passage provided in the quill corresponding to the number of the bearings, and one discharge passage communicating with the mist supply passage. term (
1) Main shaft structure described. (5) The air passage containing the liquid mist communicates with circumferential circular grooves arranged at both ends of the outer circumferential surface of the quill, and is distributed evenly in the circumferential direction on the outer circumferential surface of the quill. 2. The main shaft structure according to claim 1, further comprising a straight groove arranged in the quill and extending in the axial direction of the quill, the straight groove having a land portion.