JPS6147992B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a screw rotor tooth profile for a screw type fluid machine such as a screw compressor or an expander. The present invention relates to a method of manufacturing a rotor tooth profile suitable for a dry screw compressor in which the tooth profiles rotate with a substantially constant minute gap maintained without coming into contact with each other.

[Conventional technology]

In oil-free screw compressors, etc., which are generally used for applications where it is undesirable for oil to be mixed in the gas discharged from the screw compressor,
Rotation transmission between the pair of screw rotors is performed via a synchronizer provided on the shaft portion of each rotor outside the working chamber, and at this time, the rotor tooth profiles mesh and rotate without contacting each other. The screw rotor of this type of screw compressor has a rotor tooth profile that is at high temperature during actual operation (for example, in a single-stage compressor, when the pressure ratio is 8, the discharge gas temperature is approximately
The temperature will be 300℃, and the temperature of the rotor tooth profile will be approximately 200℃. ), the shape of the rotor teeth is significantly deformed compared to the shape of the rotor teeth at room temperature when the rotor is stopped.
Therefore, when designing the shape of both rotor tooth profiles, consider the dimensions of the rotor tooth profiles so that they do not come into contact during actual operation and there is a minimum gap between both rotor tooth profiles and between the rotor tooth profile and the casing. It is necessary to design the

Conventionally, the gap between both rotor tooth profiles is provided by using the rotor tooth profile of the male rotor at room temperature as the basic tooth profile, and taking into account the amount of deformation due to thermal expansion during actual operation, and creating a gap in the normal direction of the tooth profile of the female rotor at room temperature. A screw rotor tooth profile with a certain amount of clearance has been put into practical use.

In addition, a method of providing a gap between both rotor tooth profiles that is different from the above is that a small gap is provided in the area where the relative sliding motion between the rotor tooth profiles that mesh with each other is small, and a sufficient gap is provided between the other rotor tooth profiles. The one that gave a large gap was the special public service of 1973.
It is disclosed in No. 20061, etc.

[Problem that the invention seeks to solve]

However, in conventional rotor tooth profile design, the gap between both rotor tooth profiles and between the rotor tooth profile and the casing is uniquely determined, and a gap that has no theoretical basis is given to the rotor tooth profile. However, there are problems such as a decrease in performance efficiency due to an excessively large gap between the rotor tooth profiles, and in the worst case, a contact accident between the rotor tooth profiles may occur, resulting in a decrease in reliability.

In other words, in the former method of providing a fixed amount of gap, the deformation due to thermal expansion differs depending on the tooth profile. It cannot be said that this is a way to provide a proper gap.

In addition, in the latter method of varying the size of the gap between the rotor tooth profiles, as shown in Figure 14, the gap during actual operation (the dotted line in the figure) is set between the rotor tooth profiles compared to the gap at room temperature (the solid line in the figure). It is difficult to maintain a constant minute gap over the entire area.

An object of the present invention is to improve performance efficiency and reliability by maintaining a substantially constant minute gap over the entire area between the meshing rotor tooth profiles of the female rotor and the male rotor. An object of the present invention is to provide a method for manufacturing a rotor tooth profile for a screw type fluid machine.

[Means for solving problems]

In order to achieve the above object, the present invention provides a method for manufacturing a rotor tooth profile for a screw type fluid machine having a female rotor and a male rotor whose basic tooth profile is a pair of rotor tooth profiles that mesh with each other without a gap at room temperature. The rotor tooth profile on one side of the tooth profile is deformed as the temperature rises from room temperature to actual operation, and the rotor tooth profile is created based on this rotor tooth profile, and the rotor tooth profile is created through an almost constant minute gap without contacting this rotor tooth profile. The rotating rotor tooth profile is set as the other rotor tooth profile during actual operation, and this rotor tooth profile is deformed according to heat contraction up to room temperature to become the other rotor tooth profile at room temperature, and the one rotor tooth profile at room temperature is compared with the rotor tooth profile at room temperature. This is achieved by forming the other rotor tooth profile during manufacturing.

[Effect]

The method for manufacturing a rotor tooth profile of the present invention uses a pair of rotor tooth profiles that mesh with each other without a gap at room temperature as a basic tooth profile, and based on the rotor tooth profile of these basic tooth profiles, thermal deformation due to temperature rise from room temperature to actual operation is calculated. The rotor tooth profile during manufacturing is designed with this in mind. As a result, it is possible to maintain an almost constant minute gap over the entire area between the meshing rotor tooth profiles of the female and male rotors during actual operation, so there is no possibility of large amounts of fluid leakage or contact accidents between the tooth profiles. .

〔Example〕

An embodiment of the rotor tooth profile manufacturing method of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a female rotor, 2 is a male rotor that meshes with the female rotor 1, and both rotors 1 and 2 are rotated within a casing (not shown) with center points 3 and 4 as their rotation centers. By rotating in this direction, it fulfills the function of a compressor. 5,
6 indicates the pitch circle of both rotors 1 and 2. here,
Assuming that the basic tooth profile of the female rotor is 7 and the basic tooth profile of the male rotor is 8, the basic tooth profiles 7 and 8 of both rotors 1 and 2 are at room temperature (at the temperature when the rotor tooth profiles were manufactured, 20
These are the rotor tooth profiles that mesh with each other without any gaps in the state (approximately 7°C).
There are no restrictions on the details of the individual shapes of 8.

2 to 4 show the procedure for carrying out the present invention. In the embodiment of the present invention, the male rotor 2 is used as a reference, and the male rotor 2 has a basic tooth profile 8.
We will explain the case where .

In Figures 2 and 3, reference numeral 9 indicates a rotor tooth profile in which the basic tooth profile 8 of the male rotor is deformed by thermal expansion due to the actual operation of the rotors 1 and 2 (this rotor tooth profile is referred to as a first rotor tooth profile). ) This deformed first rotor tooth profile 9 is calculated by a method such as the finite element method based on the temperature distribution obtained by measuring the temperature inside the rotor in advance. 10 is a rotor tooth profile of the female rotor 1 created by the rotor tooth profile 9 of the male rotor 2 (this rotor tooth profile is referred to as a second rotor tooth profile);
0 is determined from the rotor tooth profile 9 deformed by the thermal expansion.

Next, by returning the rotor tooth profile 10 to the room temperature state from the actual operation according to the heat contraction of each part, the female rotor 1
The rotor tooth profile 11 at room temperature is determined. (This rotor tooth profile will be referred to as a third rotor tooth profile.) In this case, the rotor tooth profile 11 at room temperature may be determined from the temperature distribution inside the female rotor 1 using a method such as the finite element method in the same manner as described above.

By the above procedure, the rotor tooth profile of the basic tooth profile 8 and the third rotor tooth profile 11 are set as the rotor tooth profile at room temperature, that is, the rotor tooth profile formed during manufacturing.

Here, the simplest example will be explained as a specific example of the above procedure.

First, as an assumption, it is assumed that the temperature in the inner and outer sections and in the axial direction of both rotors during actual operation is uniformly distributed in the cross section perpendicular to the axis, and that the thermal expansion of the rotor due to temperature rise is from the center of the rotor to the rotor tooth profile. It shall expand in the radial direction corresponding to the distance to an arbitrary point.

In FIG. 4, the normal line of an arbitrary point 12 on the basic tooth profile 8 of the male rotor 2 is 12-13. This point 12 expands in the radial direction due to the temperature increase, and the point 14
Move to. At this time, the normal line 14-15 of point 14
moves parallel to the normal 12-13, and this point 14 lies on the rotor tooth profile 9, which has been deformed due to the temperature increase.

Thereafter, in the same manner as described above, the amount of thermal expansion at each point of the basic tooth profile 8 is calculated to determine the rotor tooth profile 9.

Next, in order to obtain the rotor tooth profile 10 of the female rotor 1 created by the rotor tooth profile 9 of the male rotor 2 deformed due to thermal expansion, when the point 15 is on the pitch point as shown in FIG. A point 16 on the mating rotor tooth profile created in step 14 is found. This point 16 lies on the rotor tooth profile 10.

In order to convert the rotor tooth profile 10 to the rotor tooth profile 11, the procedure for converting the rotor tooth profile 8 to the rotor tooth profile 9 may be reversed.

In this way, the second rotor tooth profile 10 is created by the first rotor tooth profile 9, which takes into account thermal expansion in the basic tooth profile 8, so that during actual operation, the meshing of the female rotor 1 and the male rotor 2 is reduced as will be described later. Since a substantially constant minimum gap can be maintained over the entire area between the mating tooth profiles, a significant increase in performance efficiency can be achieved, especially in dry screw rotors in operation.

That is, as shown by the dotted line in FIG. 13, the gap during actual operation is a minute amount of about 15 μm, and this minute gap is maintained almost constant over the entire area between the meshing tooth profiles of the female rotor 1 and the male rotor 2. Ru.
At this time, as shown by the solid line in the figure, a gap of about 110 μm at the maximum and about 20 μm at the minimum is provided between the pair of rotor tooth profiles at room temperature. still,
The above-mentioned gap amount varies greatly depending on usage conditions, rotor dimensions, rotor method, etc. Incidentally, the above-mentioned gap amount is when the temperature conditions are room temperature (20°C), actual operating temperature (200°C), and the rotor has an outer diameter of 90 mm.

FIG. 6 shows another embodiment different from the procedure of the previous embodiment, and in FIG. 6, the same reference numerals as in FIGS. 1 to 5 indicate the same parts.

In FIG. 6, the female rotor 1, the male rotor 2
The rotational transmission between the two rotors 1, 2 takes place via a synchronizing device, for example a synchronizing gear (not shown), provided outside the working chambers of both rotors 1, 2. Also, in this embodiment, the male rotor 2 is used as a reference as in the previous embodiment, and a basic tooth profile 8 is provided to the male rotor 2, and this basic tooth profile 8 is formed so as to be mutually free from the basic tooth profile 7 at room temperature. These are rotor tooth profiles that mesh with each other.

17 is the second rotor tooth profile 10 of the female rotor 1
Amount of backlash of synchronous gears (10 to 25 μm)
and a rotor tooth profile with a reduced minimum clearance required to prevent rotors 1 and 2 from coming into contact with each other during the meshing process (this rotor tooth profile is referred to as the third rotor tooth profile).
This shows that. Reference numeral 18 denotes a rotor tooth profile obtained by returning the third rotor tooth profile 17 to a room temperature state (this rotor tooth profile is referred to as a fourth rotor tooth profile), and this fourth rotor tooth profile 18 is similar to that of the female rotor 1. It is determined from the temperature distribution inside the rotor using techniques such as the finite element method.

By the above procedure, the rotor tooth profile of the basic tooth profile 8 and the fourth rotor tooth profile 18 are set as the rotor tooth profile formed during manufacturing.

Next, the method for determining the third rotor tooth profile 17 will be explained in the seventh section.
This will be explained using figures.

In FIG. 7, the sum of the backlash amount of the synchronous gear on the pitch circle 5 of the female rotor 1 and the required minimum gap amount between the rotors 1 and 2 is Co, and at an arbitrary point 19 on the rotor tooth profile 10 deformed by the thermal expansion, If the length of the vector radius 3-19 is R, the angle between the vector radius and the normal line of the tooth profile set at point 19 is α, and the radius from the center point 3 to the pitch circle 5 is Rp, then on the rotor tooth profile 10 An arbitrary point 19 becomes point 20 when the backlash amount and the like are considered. Point 19 at this time
If the distance of -20 is C, this distance C is expressed by the following formula.

C=R/Rp・Co・sinα According to this formula, from the second rotor tooth profile 10 deformed due to thermal expansion, the third
The rotor tooth profile 17 is determined.

Next, in order to convert the third rotor tooth profile 17 to the fourth rotor tooth profile 18, the procedure for converting the rotor tooth profile 8 to the rotor tooth profile 9 may be reversed.

In this way, the reason for considering the amount of backlash is that when using a synchronous gear etc. as a synchronizing device,
This is because in order to obtain optimal meshing during actual operation, it is necessary to consider the amount of backlash present in the synchronous gear.

In this way, by taking into account the amount of backlash of the synchronous gear on the thermally expanded female rotor and male rotor during actual operation, it is possible to prevent the tooth profiles of both rotors from coming into contact with each other during actual operation. Improved reliability. Of course, performance can be improved by providing the minimum amount of backlash within an allowable range.

FIGS. 8, 9, 11, and 12 show still other embodiments different from the procedure of the above embodiment, and FIGS.
In FIG. 2, the same reference numerals as in FIGS. 1 to 7 indicate the same parts.

The procedure of this embodiment will be explained with reference to the flowchart shown in FIG.

In this embodiment as well, the basic tooth profile 8 is used for the male rotor as the rotor tooth profile at room temperature.

First, it is assumed that the basic tooth profile 8 undergoes a certain temperature rise during actual operation, and the rotor tooth profile after thermal expansion caused by this temperature increase (this rotor tooth profile is referred to as a first rotor tooth profile 9) is determined. Next, a gap amount is assumed that takes into account the amount of backlash of the synchronous gear and the amount of gap required to prevent the rotors from coming into contact with each other, and this gap amount is added to the first rotor tooth profile 9 ( This rotor tooth profile is referred to as a second rotor tooth profile 21). From this second rotor tooth profile 21, the rotor tooth profile of the mating female rotor 1 (this rotor tooth profile is changed to the third rotor tooth profile 22)
). That is, the third rotor tooth profile 22 of the female rotor 1 obtained by generating the second rotor tooth profile 21 of the male rotor 2 is determined. Finally, a rotor tooth profile obtained by returning this third rotor tooth profile 22 to a normal temperature state (this rotor tooth profile is referred to as a fourth rotor tooth profile 23) is determined.

By the above procedure, the basic tooth profile 8 and the fourth rotor tooth profile 23 are set as the rotor tooth profile formed during production at room temperature.

By forming the tooth profiles of the female rotor 1 and the male rotor 2 at room temperature (at the time of manufacturing) in this way, the female rotor 1 is
Since the gap between the rotor and the male rotor 2 is only the minimum gap required since there is no backlash of the synchronous gear or contact between the rotors, leakage of gas etc. can be extremely reduced, and the efficiency of the screw compressor can be greatly improved. .

Further, since the amount of thermal deformation of the rotor becomes clear regarding the gap between the rotor and the casing, the gap can be set to the minimum value.

In the above embodiment of the present invention, the temperature distribution in the axial direction during actual operation is kept constant, but depending on the actual operating conditions such as the working fluid and pressure conditions, there may be a considerable temperature gradient in the axial direction of the rotor. do. For this reason, when considering the temperature distribution on the low-temperature suction side and the temperature distribution on the high-temperature discharge side, the rotor tooth profile is formed in a tapered shape with the outer peripheral side decreasing from the suction side toward the discharge side.

That is, as shown in FIG. 10, a taper is formed that tapers from one end on the suction side (A in the drawing) to the other end on the discharge side (B in the drawing).

(Illustration B) Moreover, this taper can also be provided on either one or both of the female rotor 1 and the male rotor 2.

In the embodiments of the present invention, a case is described in which the male rotor 2 is given a basic tooth profile 8 with the male rotor tooth profile as a reference, but of course, the female rotor tooth profile is used as a reference and the female rotor 1 is given a basic tooth profile 7. The same effect can be achieved by giving .

In addition, in the embodiments of the present invention, the basic tooth profile is a tooth profile that meshes with each other without a gap at normal temperature, but the tooth profile meshes with each other without a gap at temperatures other than normal temperature (temperatures above normal temperature and below actual operating temperature). The pair of rotor tooth profiles may be used as the basic tooth profile.

〔Effect of the invention〕

The present invention uses a pair of rotor tooth profiles that mesh with each other without a gap at room temperature as a basic tooth profile, and deforms one rotor tooth profile of these basic tooth profiles as the temperature rises from room temperature to actual operation. The rotor tooth profile that is created as a rotor tooth profile and rotates through an almost constant minute gap without contacting this tooth profile is used as the other rotor tooth profile during actual operation, and this rotor tooth profile is deformed according to heat contraction up to room temperature. By doing so, the other rotor tooth profile at room temperature is set, and the one rotor tooth profile at room temperature and the other rotor tooth profile at room temperature are formed during manufacturing, so that the pair of female rotor and male rotor mesh during actual operation. Since it is possible to maintain a substantially constant minute gap over the entire area between the rotor tooth profiles, it is possible to significantly improve performance efficiency by reducing fluid leakage of fluid machines such as screw compressors.

Further, since it is possible to prevent accidents such as contact between the teeth of both rotors during actual operation, reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a basic tooth profile in the method for manufacturing a rotor tooth profile for a screw-type fluid machine according to the present invention, and FIGS. Figures 6 and 7 are diagrams showing an embodiment and explaining the procedure for determining the rotor tooth profile. Figure, Figure 8, Figure 9
11 and 12 show still another embodiment of the method of the present invention, and FIG. 10 shows still another embodiment of the method of the present invention. Side view showing,
FIGS. 13 and 14 are diagrams for explaining the gap amount between the female rotor and the male rotor according to the method of the present invention and the conventional method during actual operation and at room temperature. 1... Female rotor, 2... Male rotor, 7, 8... Basic tooth profile.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a rotor tooth profile for a screw type fluid machine equipped with a female rotor and a male rotor whose basic tooth profile is a pair of rotor tooth profiles that mesh with each other without a gap at room temperature, wherein one of the basic tooth profiles is The rotor tooth profile is deformed as the temperature rises from room temperature to actual operation, and the rotor tooth profile is created based on this rotor tooth profile.
In addition, the rotor tooth profile that rotates through an almost constant minute gap without contacting this rotor tooth profile is used as the other rotor tooth profile during actual operation, and this rotor tooth profile is deformed according to heat contraction up to room temperature. A method for manufacturing a rotor tooth profile for a screw-type fluid machine, characterized in that the other rotor tooth profile is formed at normal temperature and the other rotor tooth profile at normal temperature is formed during manufacturing. 2. In the method for manufacturing a rotor tooth profile for a screw-type fluid machine according to claim 1, one rotor tooth profile of the basic tooth profile is deformed according to thermal expansion from room temperature to actual operation. 1 rotor tooth profile, the other rotor tooth profile is created by this first rotor tooth profile to provide a second rotor tooth profile, and a rotor tooth profile obtained by subtracting the backlash of the synchronizer from this second rotor tooth profile is defined as a third rotor tooth profile; The fourth rotor tooth profile is obtained by deforming the third rotor tooth profile according to heat contraction from actual operation to room temperature.
A method for manufacturing a rotor tooth profile for a screw type fluid machine, characterized in that one rotor tooth profile at normal temperature and a fourth rotor tooth profile at normal temperature are formed during manufacturing. 3. In the method for manufacturing a rotor tooth profile for a screw-type fluid machine according to claim 1, a first rotor tooth profile is obtained by adding an amount of thermal expansion from room temperature to actual operation to one rotor tooth profile of the basic tooth profile. The rotor tooth profile is defined as the rotor tooth profile, and the rotor tooth profile obtained by adding the backlash amount of the synchronizer to the first rotor tooth profile is defined as the second rotor tooth profile, and the other rotor tooth profile is created using this second rotor tooth profile to define the third rotor tooth profile. A rotor tooth profile obtained by deforming the third rotor tooth profile according to heat contraction from actual operation to room temperature is defined as a fourth rotor tooth profile, and the one rotor tooth profile at room temperature and the fourth rotor tooth profile at room temperature are formed during manufacturing. A method for manufacturing a rotor tooth profile for a screw-type fluid machine, characterized in that: