JP2003136367A - Spindle cooling method, and processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle cooling method, and a processing device, capable of improving position precision of a processed hole even in case heat generation quantity at a spindle is varied. SOLUTION: This device is provided with a spindle 11 to rotatably support a rotor, a coolant supply device 30 to supply fluid (coolant) at preset temperature to a passage formed in the spindle 11, and a circulation passage 35 to circulate the fluid between the spindle 11 and the coolant supply device 30. The spindle 11 is cooled by the fluid. A flow rate regulating device 50 is provided to regulate the flow rate of the fluid supplied to the spindle 11 based on temperature of the fluid discharged from the spindle 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle cooling method for cooling a spindle by supplying a temperature-controlled fluid to the inside of a spindle that rotatably supports a rotor, and such a spindle. Regarding processing equipment.

[0002]

2. Description of the Related Art FIG. 7 is a perspective view showing the overall construction of a conventional printed circuit board boring machine, FIG. 8 is an explanatory view of a spindle, and FIG. 8A is a longitudinal sectional view of the spindle. The same figure (b) is the sectional view on the AA line of the figure (a).
FIG. 9 is a piping system diagram of the cooling fluid of FIG.

In FIG. 7, the printed circuit board drilling machine M is
The bed 1 is basically composed of a bed 2, a table 2 movably installed on the bed 1 in a predetermined direction, and a column 3 fixed on the bed 1.

The table 2 is supported on a guide (not shown) provided on the bed 1 so as to be movable in the arrow X direction. The column 3 has a support leg at both ends for the table 2
It is fixed to the bed 1 so as to straddle it, and a pair of first guides 4 are horizontally provided on the work side surface. The first guides 4 are fixed to the surface at predetermined intervals, and the cross slides 5 are supported by the first guides 4. The cross slide 5 is also provided with a pair of second guides 7 in the vertical direction, and the cross slide 5 itself is moved in the direction of the arrow Y along the first guide 4 by the screw feeding means using the cross slide drive motor 6 as a drive source. It is free to move. The second guide 7 is fixed to the work-side surface of the cross slide 5 at a predetermined interval, the saddle 8 is supported by the second guide 7, and the housing 10 is fixed to the saddle 8 at a predetermined interval. Further, a spindle 11 is rotatably supported on the housing 10. The saddle 8 can be moved along the second guide 7 in the arrow Z direction (direction perpendicular to the table 2) by a screw feeding means using a saddle drive motor 9 as a drive source.

As shown in FIG. 8, a plurality of cooling liquid passages 20 for passing a cooling fluid (hereinafter referred to as "cooling liquid") are formed inside the spindle 11. Both ends of the cooling liquid passage 20 communicate with the first and second annular communication passages 21 and 22, respectively, and are gathered together. The first communication passage 21 is provided with a cooling liquid supply device 30 via a cooling liquid inlet 23.
Of the cooling liquid supply port 31, and the second communication passage 22 is connected to the return port 3 of the cooling liquid supply device 30 via the cooling liquid outlet 24.
Connected to 2. The cooling liquid supply device 30 has a return port 3
It has a function of cooling the temperature-increased cooling liquid returned from 2 to a set temperature and supplying the cooled cooling liquid again from the supply port 31 to the spindle 11 side.

The spindle 11 holds the rotor shaft 25 in a state of being positioned in the thrust direction and the radial direction by an air bearing (not shown). A rotor (rotor) is provided on the outer peripheral portion of the rotor shaft 25.
Is provided, and a coil is arranged at a position facing the rotor inside the spindle 11. A drill 26 is detachably held at the tip of the rotor shaft 25, as shown in FIG.
A circulation path 35 is formed between the return port 32 and the return port 32, and the four spindles 11 are connected to the circulation path 35 in parallel with the cooling liquid supply device 30. At the time of processing, the cooling liquid supply device 30 is operated to supply the cooling liquid having a constant temperature and a constant flow rate to each inlet 23, and the rotor shaft 25 is rotated. Then, after moving the table 2 and the cross slide 5 to position the axis of the drill 26 at the processing position,
The saddle 8, that is, the drill 26 is moved in the vertical (Z) direction to form a hole in the printed circuit board 12 fixed on the table 2. In the case of the illustrated printed circuit board drilling machine M, since four spindles 11 are provided, four printed circuit boards 1 are provided.
2 can be processed simultaneously, and the processing efficiency can be improved.

Although the spindle 11 generates heat due to the current flowing through the coil, etc., since the spindle 11 is cooled by the cooling liquid, the displacement of the drill 26 due to the heat generation of the spindle 11 is small. However, the variation in processing accuracy can be set to about 5 μm.

The appropriate rotation speed of the drill (that is, the rotor shaft) differs depending on the diameter of the hole to be machined. For example, in the case of a 0.5 mm hole, 20,000 rotations per minute (hereinafter, notation for each minute is omitted. In the case of a 0.3 mm hole, 80,000 rotations and in the case of a 0.1 mm hole, 160,000 rotations, a high quality hole can be efficiently processed.

[0009]

In recent years, the density of printed circuit boards has increased, and the diameter of 0.3 m, which was the smallest diameter in the past, has been achieved.
It is required to machine a hole having a diameter of 0.1 mm, which is smaller than m, and it is required to make the positional accuracy variation less than 5 μm.

However, in the conventional printed circuit board drilling machine,
The position accuracy may vary depending on the processed hole diameter. That is, 1 processed with the same spindle
Even with a single printed circuit board, for example, the positional accuracy of the 0.1 mm hole may differ from the positional accuracy of the 0.3 mm hole.

FIG. 10 is a diagram showing the results of measuring the temporal change in the amount of heat absorbed by the cooling liquid using the number of rotations of the drill as a parameter. Is. As shown in the figure, although the initial amount of heat absorption varies depending on the flow rate of the cooling liquid (a>b> c), the maximum value of heat absorption hardly changes. Moreover, even in the case of the flow rate c, the time required to reach the maximum value is much shorter than the normal processing time. Therefore, even if the flow rate of the cooling liquid is increased, the temperature rise value of the spindle hardly changes. That is, when the temperature rise value of the cooling liquid is determined, the minimum cooling liquid flow rate when the heat generation amount is maximum is determined.

Further, as shown in FIG. 11, when the flow rate of the cooling liquid is kept constant, the temperature rise value of the cooling liquid is 7 ° C. at a drill rotation speed of 160,000 rotations, 4 ° C. at 80,000 rotations and 20,000 rotations. 2 by rotation
It is about ℃. The time T until the temperature rise value becomes substantially constant is about 30 seconds. Then, as the temperature rise value of the spindle increases, the characteristics of the air bearing and the like change, and the displacement of the axis line of the drill increases substantially in proportion to the temperature rise value of the cooling liquid. Further, even if the number of rotations of the drill is the same, the amount of heat generated differs from spindle to spindle. Therefore, even if the flow rate of the cooling liquid supplied to the spindle is the same, the amount of displacement differs from spindle to spindle.

The present invention has been made in view of the circumstances of the prior art as described above, and an object thereof is to improve the positional accuracy of a machined hole even when the amount of heat generated by the spindle changes. (EN) Provided are a spindle cooling method and a machining apparatus capable of performing the same.

[0014]

To achieve the above object, the first means is to supply a temperature-controlled fluid to the inside of a spindle that rotatably supports a rotor to cool the spindle. In the method for cooling a spindle, the outlet temperature of the fluid discharged from the spindle is detected, and the outlet temperature is supplied to the spindle so that the outlet temperature becomes a preset temperature based on the detected outlet temperature. It is characterized in that the flow rate of the fluid is adjusted.

In this case, when the outlet temperature is lower than a preset temperature, the fluid discharged from the spindle may be returned to the fluid inlet of the spindle to raise the temperature of the spindle.

The second means is a spindle for rotatably supporting the rotor, a supply means for supplying a fluid having a preset temperature to a flow passage formed inside the spindle, the spindle and the supply. And a circulation path for circulating the fluid to and from the means, wherein the spindle is cooled by the fluid, the fluid being supplied to the spindle based on the temperature of the fluid discharged from the spindle. It is characterized by comprising an adjusting means for adjusting the flow rate.

In this case, there is provided a detecting means for detecting the temperature of the fluid, and the adjusting means adjusts the outlet temperature to a preset temperature based on the temperature of the fluid detected by the detecting means. The flow rate of the fluid supplied to is adjusted.

Fluid return means may be provided for returning the fluid directly to the circulation path upstream of the spindle based on the temperature of the fluid discharged from the spindle without returning to the supply means side.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cooling liquid piping system diagram of a processing apparatus according to a first embodiment of the present invention, and FIG. 2 is a front sectional view of a flow rate adjusting device. Each section equivalent to the conventional example shown in FIG. Are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 1, the cooling liquid inlets 23 of the four spindles 11 are connected in parallel to the supply ports 31 of the cooling liquid supply device 30. The cooling liquid outlets 24 of the spindles 11 are respectively connected in series to the flow rate adjusting device 50, and the flow rate adjusting device 50 is connected in parallel to the return port 32 of the cooling liquid supply device 30. That is, in this embodiment, the cooling liquid passage 20 of the spindle 11 is connected in series with the flow passage of the flow rate adjusting device 50, and the cooling liquid passage 20 of each spindle 11 and the flow passage of the flow amount adjusting device 50 are connected in series. And are connected in parallel to the cooling liquid supply device 30.

In FIG. 2, the flow rate adjusting device 50 is mainly composed of a thermo element 51, a piston 53, a holder 54 and a case 52 accommodating them.
A first cylinder 57 is formed on the upstream side of the case 52 in the flow direction of the cooling liquid, and a second cylinder 58 is formed on the downstream side of the case 52. The two cylinders 57, 58 are connected by a pipe line 56. Further, the thermoelement 51 and the holder 54 are arranged in the cylinders 57 and 58, respectively. A piston 53 integrated with a holder 54 is connected to the thermoelement 51 so as to be inserted into the holder 54.
Moves integrally with the piston 53. At a position of the holder 54 facing the one opening (valve seat) 56a of the pipe 56, a valve body 55 is provided so as to be coaxial with the pipe 56, and a valve element 55 is provided depending on the position of the holder 54. The opening can be set.

A resin (for example, wax) is enclosed inside the thermoelement 51. The piston 53 is movably supported in the thermoelement 51, the wax expands and contracts according to the temperature of the thermoelement 51, the piston 53 moves according to the expansion and contraction, and the wax integrally moves according to the movement of the piston. The holder 54 moves. When the wax is most contracted, the piston 53 moves to the leftmost, and accordingly, the area of the annular flow path formed by the valve body 55 and the opening 56a is 20 times the opening area of the opening 56a.
% (That is, the valve opening is 20%), and when the wax is most expanded and the piston 53 is most extended, the tip of the valve body 55 is at the same position as the opening edge of the opening 56a (that is, the valve opening is 100%). become. The other opening of the pipe line 56 is opened to the first cylinder 57 side, communicates with the cooling liquid outlet 24 of the spindle 11, and the second cylinder 58 is connected to the cooling liquid supply device 3.
0 is connected to the return port 32 side.

The resin sealed in the thermoelement 51 changes from solid to liquid and does not change in volume until the temperature of the cooling liquid supplied from the cooling liquid supply device 30 rises by 7 ° C. . And the temperature rise value is 7 ℃
When it exceeds, the expansion starts. As a result, the piston 53
Indicates that the temperature difference of the cooling liquid discharged from the spindle 11 is 7
If the temperature is below ℃, it does not move (hereinafter, the temperature at which the piston 53 starts moving is referred to as "piston operating temperature"), and 7
When the temperature exceeds ℃, it starts moving to the right in FIG. 2 and changes the valve opening.

Next, the operation of this embodiment will be described. The initial valve opening is 20%.

FIG. 3 is a diagram showing the changes over time in the valve opening and the temperature rise value of the cooling liquid after the start of processing. (A) shows the valve opening, and (b) shows the amount of heat absorbed at the outlet 24. Shows.

(1) When the number of rotations of the drill is 20,000, since the valve opening is 20%, the temperature rise value of the cooling liquid discharged from the spindle 11 becomes 7 ° C. Since this value is below the piston operating temperature, the valve opening does not change. Therefore, the spindle 11 is kept at the temperature rise value of 7 ° C.

(2) When the number of drill revolutions is 80,000, the valve opening is 20%, so the temperature rise value of the coolant discharged from the spindle 11 exceeds 7 ° C. (piston operating temperature) (time T2). ). For this reason, the valve opening is increased by the gradual movement of the piston 53, and the flow rate of the cooling liquid is increased. Then, when the valve opening becomes 50%, the temperature rise value of the discharged cooling liquid drops to 7 ° C.
3 stops moving. Therefore, the spindle 11 is kept at the temperature rise value of 7 ° C.

(3) When the number of rotations of the drill is 160,000, since the valve opening is 20%, the temperature rise value of the cooling liquid discharged from the spindle 11 exceeds 7 ° C. (piston operating temperature) (time T1 ). For this reason, the valve opening is increased by the gradual movement of the piston 53, and the flow rate of the cooling liquid is increased. Then, when the valve opening becomes 100%, the temperature rise value of the discharged cooling liquid drops to 7 ° C. Therefore,
The spindle 11 is kept at a temperature rise value of 7 ° C.

As described above, according to this embodiment, the temperature rise value of the cooling liquid,
That is, since the temperature rise value of the spindle 11 is always maintained at the same value, the amount of displacement of the drill due to heat generation of the coil becomes substantially the same. As a result, the machining accuracy does not change depending on the number of rotations of the drill.

Further, when a plurality of spindles are simultaneously operated with the same number of drill rotations, the temperature rise values of the respective spindles are made substantially equal by changing the flow rate of the cooling liquid even if the heat generation amounts of the spindles 11 are different. Therefore, the displacement of the drill does not vary, and the processing accuracy can be made uniform.

(Second Embodiment) FIG. 4 is a piping system diagram of a cooling liquid according to a second embodiment of the present invention, and FIG. 5 is a vertical cross-sectional view of a flow rate adjusting device shown in FIGS. 1 and 2. The same parts as those in the first embodiment and the conventional example shown in FIG. 9 are designated by the same reference numerals, and duplicate description will be omitted.

In this embodiment, as shown in FIG. 4, the flow rate adjusting device 50 and the spindle 1 in the first embodiment are shown.
A return pipe 63 provided with a check valve 62 is provided between the upstream side of the cooling liquid inlet 23 and the upstream side 61 of the return pipe 63 as shown in FIG. It is open. As a result, the cooling liquid flows from the pipe 56 into the return pipe 63 in accordance with the pressure states of the upstream side and the downstream side of the valve body 55, passes through the check valve 61, and reaches the upstream side of the cooling liquid inlet 23 of the spindle 1. It can be returned to the side and supplied again into the spindle 11. The check valve 62 is used as the coolant inlet 2 of the spindle 11.
3 from the upstream side of the flow rate adjusting device 50 to the pipe line 56 of the flow rate adjusting device 50, the flow of the cooling liquid is directed from the flow rate adjusting device 50 to the upstream side of the cooling liquid inlet 23 of the spindle 11. It is regulated only.

In order to reveal the pressure relationship, it is necessary to set the pressure on the return pipe 63 side to be lower than the pressure on the second cylinder 58 side. Therefore, in the present embodiment, unlike the above-described first embodiment, the valve opening degree at the start of processing is set to, for example, about 5% so as to be smaller than 20%. In this way, at the start of processing, the cooling liquid discharged from the spindle 11 does not return from the flow rate adjusting device 50 side to the cooling liquid supply device 30 side to be cooled, but directly to the cooling liquid inlet 23 side of the spindle 11. To heat the spindle 11. Therefore, as shown in FIG. 6, the rising characteristic of the temperature rise of the spindle 11 is improved and the steady temperature is reached in a short time, so that the hole position accuracy at the start of machining can be further improved.

In this embodiment, the flow rate adjusting device 50
The return conduit 63 is connected to the return conduit 6.
It is also possible to connect 3.

In addition, each part not particularly explained is the same as the first
Is configured and functions in the same manner as the embodiment of FIG.

In the above two embodiments, the case where the thermoelement 51 having a temperature detecting function and a piston moving function is used has been described. However, a temperature detector (for example, a temperature sensor) for detecting the temperature of the cooling liquid is used. It is also possible to provide a flow rate adjusting valve on the outlet side of each spindle 11 and adjust the flow rate of the cooling liquid supplied to the spindle 11 by the flow rate adjusting valve according to the temperature detected by the temperature detector. As the flow rate adjusting valve, for example, a valve whose opening degree can be adjusted by a motor is used.
According to the program stored in M, the CPU (not shown)
If the motor is controlled by using AM, it can be easily controlled electrically.

Further, in the above embodiment, the multi-axis machining apparatus provided with a plurality of spindles 11 has been described, but it goes without saying that the present invention can be applied to a machining apparatus having one spindle. Absent.

[0039]

As described above, according to the present invention,
The outlet temperature of the fluid flowing out from the spindle is detected, and the flow rate of the fluid supplied to the spindle is adjusted so that the outlet temperature reaches a predetermined temperature. The position accuracy of can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a piping system for a cooling liquid according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the flow rate adjusting device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a temporal change in a valve opening degree and a temperature rise value of a cooling liquid after the start of processing in the first embodiment of the present invention.

FIG. 4 is a diagram showing a piping system for a cooling liquid according to a second embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a flow rate adjusting device according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a temporal change in a temperature rise value of a cooling liquid according to the second embodiment of the present invention.

FIG. 7 is a diagram showing an overall configuration of a conventional printed circuit board boring machine (processing device).

8 is a cross-sectional view of the spindle shown in FIG.

FIG. 9 is a diagram showing a conventional coolant piping system.

FIG. 10 is a diagram showing a temporal change in the amount of heat absorption.

FIG. 11 is a diagram showing a temporal change in a temperature rise value of a conventional cooling liquid.

[Explanation of symbols]

11 spindles 23 Coolant inlet 24 Coolant outlet 30 Coolant supply device 50 Flow control device 63 Return line

Claims (5)

[Claims] 1. A method for cooling a spindle, wherein a temperature-controlled fluid is supplied to the inside of a spindle that rotatably supports a rotor to cool the spindle, and an outlet temperature of the fluid discharged from the spindle. Is detected, and the flow rate of the fluid supplied to the spindle is adjusted so that the outlet temperature reaches a preset temperature on the basis of the detected outlet temperature. 2. When the outlet temperature is lower than a preset temperature, the fluid discharged from the spindle is returned to the fluid inlet of the spindle to raise the temperature of the spindle. The method for cooling a spindle according to claim 1. 3. A spindle for rotatably supporting a rotor, a supply means for supplying a fluid of a preset temperature to a flow passage formed inside the spindle, and the spindle and the supply means. A processing apparatus having a circulation path for circulating a fluid, wherein the spindle is cooled by the fluid, and adjusting the flow rate of the fluid supplied to the spindle based on the temperature of the fluid discharged from the spindle. A processing apparatus comprising means. 4. A detecting means for detecting the temperature of the fluid, wherein the adjusting means controls the spindle so that the outlet temperature becomes a preset temperature based on the temperature of the fluid detected by the detecting means. The processing apparatus according to claim 3, wherein a flow rate of the fluid to be supplied is adjusted. 5. A fluid returning means for returning the fluid to the circulation path upstream of the spindle based on the temperature of the fluid discharged from the spindle without returning to the supply means side. The processing device according to claim 3.