JP2004268188A - Method of manufacturing needle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a needle by a novel work method different from a conventional work method. <P>SOLUTION: Among a needle valve for forming a tapered part 44b having the cross-sectional area reducing toward the tip side, at least a conical tapered part 44b is manufactured by vibrational cutting work. Thus, since the needle valve 44 can be prevented from deflecting in cutting work of the conical tapered part 44b, sufficient dimensional accuracy is provided. Since a cutter 102 is vibrationally displaced, a tip part of the conical tapered part 44b substantially slow in a peripheral speed, and becoming zero in a cutting speed, is also easily worked. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a needle having a tapered portion whose cross-sectional area is reduced toward the distal end while controlling the degree of opening of the nozzle.
[0002]
[Prior art]
BACKGROUND ART Conventionally, a conductive plastic material made of short metal fibers and a synthetic resin has been manufactured by vibration cutting (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-59-191747.
[Problems to be solved by the invention]
By the way, the needle valve of the variable ejector used in the vapor compression refrigerator has a diameter of a cylindrical portion of about 3 mm to 8 mm, and a taper angle (see JIS B 0154) of a conical tapered portion provided on the tip side. It is about 2 ° to 15 ° and high dimensional accuracy is required.
[0005]
Then, the applicant processed the conical taper portion by ordinary cutting using a lathe, but the work (needle valve) was bent by the cutting resistance, and sufficient dimensional accuracy could not be obtained.
[0006]
Further, since the peripheral speed of the tip of the needle valve is low and the cutting speed becomes substantially zero, the tip of the needle valve cannot be processed by ordinary cutting using a lathe.
[0007]
For this purpose, a method of processing the conical taper portion by polishing can be considered, but in the polishing process, depending on the material of the needle valve, the grindstone is easily clogged, and the workability is significantly reduced compared to the cutting process. It is highly likely that
[0008]
In addition, it is necessary to set the polishing allowance to a predetermined value by a cutting process or the like before performing the polishing process, but if the polishing allowance varies, the axial finish dimension of the conical taper portion varies in response to this. Sufficient dimensional accuracy cannot be obtained.
[0009]
In view of the above, an object of the present invention is to manufacture a needle by a new processing method different from the conventional method.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided a method of manufacturing a needle having a tapered portion (44b) having a cross-sectional area decreasing toward a distal end side. The part (44b) is manufactured by vibration cutting.
[0011]
In vibration cutting, as described in the January 2001 issue of “Mechanical Technology” (Vol. 49, No. 1) published by Nikkan Kogyo Shimbun, (1) cutting resistance is smaller than continuous cutting. 2) Geometric surface roughness can be improved. 3) Processing temperature is less likely to increase compared to continuous cutting, so that thermal distortion is less likely to occur on the work. 4) Constituent cutting edges are less likely to adhere. 4) It has features such as extending the life of the tool (bite).
[0012]
Therefore, it is possible to prevent the needle from being bent at the time of cutting the tapered portion (44b), so that sufficient dimensional accuracy can be obtained.
[0013]
Further, since the blade is vibrated and displaced, the tip of the tapered portion (44b) where the peripheral speed is slow and the cutting speed becomes substantially zero can be easily machined.
[0014]
The invention according to claim 2 is characterized in that the blade edge of the blade is vibrated and displaced with respect to the needle at a frequency of 15 kHz or more and 25 kHz or less.
[0015]
The invention according to claim 3 is characterized in that the blade is vibrated and displaced with respect to the needle so that the blade draws an elliptical trajectory.
[0016]
The invention according to claim 4 is characterized in that the cutting edge is vibrated and displaced with respect to the needle such that the cutting edge draws a linear trajectory.
[0017]
Incidentally, reference numerals in parentheses of the above-mentioned units are examples showing the correspondence with specific units described in the embodiments described later.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
In this embodiment, the present invention is applied to a needle valve of a variable ejector applied to an ejector cycle for a vehicle air conditioner, and FIG. 1 is a schematic diagram of an ejector cycle 1 using carbon dioxide as a refrigerant. 2 is a schematic diagram of the ejector 40.
[0019]
In FIG. 1, a compressor 10 is a well-known variable displacement compressor that draws power from a traveling engine to suck and compress refrigerant, and a discharge capacity of the compressor 10 is a temperature in an evaporator 30 described later. Alternatively, the pressure is controlled to be within a predetermined range.
[0020]
The radiator 20 is a high-pressure side heat exchanger that cools the refrigerant by exchanging heat between the refrigerant discharged from the compressor 10 and the outdoor air, and the evaporator 30 performs heat exchange between the air blown into the room and the liquid-phase refrigerant. This is a low-pressure side heat exchanger that evaporates the liquid phase refrigerant to evaporate the refrigerant and cool the air blown into the room.
[0021]
The ejector 40 decompresses and expands the refrigerant to suck the gas-phase refrigerant evaporated in the evaporator 30, and converts the expansion energy into pressure energy to increase the suction pressure of the compressor 10, which will be described in detail later. .
[0022]
The gas-liquid separator 50 is a gas-liquid separator that stores therein the refrigerant that flows out of the ejector 40 and separates the refrigerant that has flowed into a gas-phase refrigerant and a liquid-phase refrigerant. The gas-phase refrigerant outlet is connected to the suction side of the compressor 10, and the liquid-phase refrigerant outlet is connected to the inlet side of the evaporator 30. The throttle 60 is a pressure reducing means for reducing the pressure of the liquid refrigerant flowing out of the gas-liquid separator 50.
[0023]
Next, the ejector 40 will be described.
[0024]
As shown in FIG. 2, the ejector 40 converts the pressure energy of the inflowing high-pressure refrigerant into velocity energy and decompresses and expands the refrigerant in an isentropic manner. A mixing unit 42 that mixes the refrigerant flow ejected from the nozzle 41 while sucking the vapor-phase refrigerant evaporated at 30, and a velocity energy while mixing the refrigerant ejected from the nozzle 41 and the refrigerant sucked from the evaporator 30. To a pressure energy to increase the pressure of the refrigerant.
[0025]
In addition, the nozzle 41 has a throat portion 41a having the smallest passage area in the middle of the passage, and a nozzle diffuser portion 41b set so that the substantial refrigerant passage cross-sectional area S is gradually increased after the throat portion 41a. The Laval nozzle (see Fluid Engineering (Tokyo University Press)) is used. The adjustment of the throttle opening of the nozzle 41, that is, the substantial minimum cross-sectional area of the refrigerant passage is performed by moving the needle valve 44 in the nozzle 41 by the actuator 45 in the axis of the nozzle 41. This is done by displacing in the direction.
[0026]
In the needle valve 44, the diameter of the cylindrical portion 44a is about 3 mm to 8 mm, the taper angle of the conical taper portion 44b provided on the tip side is about 2 ° to 15 °, and the tip of the conical taper portion 44b is Is made of metal having excellent corrosion resistance and high hardness, such as stainless steel (for example, SUS303) rounded to about 0.3 mm or less.
[0027]
Incidentally, in the present embodiment, an electric actuator such as a stepping motor or a linear solenoid using a screw mechanism is employed as the actuator 45, and the temperature of the high-pressure side refrigerant is detected by a temperature sensor (not shown). The throttle opening of the nozzle 41 is controlled such that the refrigerant pressure on the high pressure side detected by the pressure sensor (not shown) becomes the target pressure determined from the temperature detected by the temperature sensor.
[0028]
Here, the target pressure is a high-pressure side refrigerant pressure at which the coefficient of performance of the ejector cycle becomes highest with respect to the high-pressure side refrigerant temperature. In the present embodiment, when the heat load is large, the target pressure flows into the nozzle 41. The throttle opening of the nozzle 41 is controlled so as to raise the pressure of the high-pressure refrigerant to the pressure equal to or higher than the critical pressure of the refrigerant. When the heat load is small, the refrigerant flowing into the nozzle 41 with the pressure of the high-pressure refrigerant set at the critical pressure or lower is reduced. The throttle opening of the nozzle 41 is controlled so as to have a predetermined degree of supercooling.
[0029]
Next, the general operation of the ejector cycle will be described.
[0030]
The refrigerant discharged from the compressor 10 is circulated to the radiator 20 side. Thus, the refrigerant cooled by the radiator 20 isentropically decompressed and expanded at the nozzle 41 of the ejector 40 and flows into the mixing section 42 at a speed higher than the speed of sound.
[0031]
Then, the refrigerant evaporated in the evaporator 30 is sucked into the mixing section 42 by the pumping action accompanying the entraining action of the high-speed refrigerant flowing into the mixing section 42, so that the low-pressure side refrigerant is removed from the gas-liquid separator 50 → throttle. The circulation is performed in the order of 60 → evaporator 30 → ejector 40 (mixing section 42, diffuser 43) → gas-liquid separator 50.
[0032]
On the other hand, while the refrigerant sucked from the evaporator 30 (suction flow) and the refrigerant blown out from the nozzle 41 (drive flow) are mixed in the mixing section 42, the dynamic pressure thereof is converted to static pressure in the diffuser 43, and Return to the liquid separator 50.
[0033]
Next, a method for manufacturing the needle valve 44 will be described.
[0034]
FIG. 3 is a schematic view showing a manufacturing apparatus (for example, a numerically controlled lathe) 100 of the needle valve 44. The needle valve 44, which is a work, has a cylindrical portion 44a fixed to a chuck 101 and rotates around a central axis at a predetermined rotation speed. Rotated.
[0035]
Then, the workpiece is intermittently cut while vibratingly displacing the cutting edge of the cutting tool (bite) 102 with respect to the needle valve 44. The blade 102 is held by a holder 103, and the blade 102 is displaced by vibration via the holder 103. The ultrasonic vibration generator 104 is a control device that controls the frequency of the blade 102.
[0036]
At this time, in the present embodiment, as shown in FIG. 4, the trajectory drawn by the cutting edge is an elliptical (elliptical) trajectory orbiting in the same direction as the rotation direction of the needle valve 44, and is not less than 15 KHz and not more than 25 KHz. The blade 102 is vibrated at the frequency.
[0037]
Next, a method for manufacturing the needle valve 44 according to the present embodiment will be described.
[0038]
In vibration cutting, as described in the January 2001 issue of “Mechanical Technology” (Vol. 49, No. 1) published by Nikkan Kogyo Shimbun, (1) cutting resistance is smaller than continuous cutting. 2) Geometric surface roughness can be improved. 3) Processing temperature is less likely to increase compared to continuous cutting, so that thermal distortion is less likely to occur on the work. 4) Constituent cutting edges are less likely to adhere. 4) It has features such as extending the life of the tool (bite).
[0039]
Therefore, it is possible to prevent the needle valve 44 from being bent at the time of cutting the conical tapered portion 44b, so that sufficient dimensional accuracy can be obtained.
[0040]
In addition, since the blade 102 is displaced by vibration, the tip of the conical tapered portion 44b where the peripheral speed is low and the cutting speed becomes substantially zero can be easily processed.
[0041]
(Other embodiments)
In the above-described embodiment, a Laval nozzle is used as the nozzle 41, but the present invention is not limited to this. For example, a tapered nozzle may be used.
[0042]
Further, in the above-described embodiment, the refrigerant is carbon dioxide, and the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure of the refrigerant. For example, when the refrigerant is Freon such as R134a and the pressure of the refrigerant on the high pressure side is lower than the critical pressure, the refrigerant changes phase in the radiator 20 to lower the enthalpy.
[0043]
Further, in the above-described embodiment, the work is intermittently cut while the blade is vibrated and displaced with respect to the needle valve 44. However, the present invention is not limited to this. For example, the blade may draw a linear locus. As described above, the workpiece may be intermittently cut while the blade tip is vibrated and displaced with respect to the needle valve 44.
[0044]
Further, in the above-described embodiment, the present invention is applied to the method of manufacturing the needle valve 44 for the variable ejector that controls the opening degree of the nozzle 41, but the application of the present invention is not limited to this. It may be used in a method for manufacturing a carburetor needle.
[0045]
Further, the conical taper portion 44b of the needle valve 44 according to the above-described embodiment has a constant taper angle, but the application of the present invention is not limited to this, and for example, the taper angle is set to the distal end side. The taper angle may change so as to increase, or the taper angle may change so as to decrease toward the distal end.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an ejector cycle according to an embodiment of the present invention.
FIG. 2 is a schematic view of an ejector according to the first embodiment of the present invention.
FIG. 3 is a schematic view showing a needle valve manufacturing apparatus.
FIG. 4 is a diagram illustrating a relationship between a workpiece and a cutting edge locus.
[Explanation of symbols]
44: needle valve, 44b: conical tapered portion, 100: NC lathe,
101: chuck, 102: blade (bite), 103: holder,
104: Ultrasonic vibration generator.

Claims (4)

A method for manufacturing a needle having a tapered portion (44b) whose cross-sectional area decreases toward the distal end,
A method for manufacturing a needle, wherein at least the tapered portion (44b) is manufactured by vibration cutting. The method for manufacturing a needle according to claim 1, wherein the cutting edge of the blade is displaced with respect to the needle at a frequency of 15 KHz or more and 25 KHz or less. The method for manufacturing a needle according to claim 1, wherein the cutting edge is vibrated and displaced with respect to the needle such that the cutting edge draws an elliptical trajectory. The method for manufacturing a needle according to claim 1, wherein the cutting edge is vibrated and displaced with respect to the needle such that the cutting edge draws a linear trajectory.

Images