JP5992286B2 - Screw rotor processing method - Google Patents

Description

The present invention relates to a method for processing the screw rotor having an odd number of rotor teeth.

  A screw rotor incorporated in a screw compressor or the like has a complicated three-dimensional shape in which rotor teeth are formed in a spiral shape. The performance of a screw compressor or the like greatly depends on the processing accuracy of the screw rotor. For the processing of the screw rotor, a rotor bar cutting is performed on a round bar material finished to a predetermined outer diameter, and the root diameter of the rotor groove is measured while measuring the root diameter of the rotor tooth with a micrometer or the like. (Diameter) was finished to a predetermined dimension. Patent Document 1 discloses a processing technique in which a round bar material is rotatably mounted on a headstock of an NC machine tool, and a screw groove is formed on the outer diameter of the round bar material.

  7A to 7C show a screw rotor used in a screw compressor. In the figure, the screw rotor 100 includes a male rotor 102 and a female rotor 104, and the rotor teeth 106 of the male rotor 102 and the rotor teeth 108 of the female rotor 104 mesh with each other to form a compression space. As for the number of rotor teeth of the male rotor 102 and the female rotor 104, for example, as shown in FIG. 7A, for example, a screw rotor having an even number [four male rotors + six female rotors] rotor teeth is used. It was. However, after that, the need for higher performance by increasing the pressure has increased, and the number of rotor teeth tends to increase. As shown in FIGS. 7B and 7C, an odd number of rotor teeth [five male rotors] Screw rotors having +6 female rotors or 5 male rotors + 7 female rotors] have been used.

  In the case of even-numbered teeth shown in FIG. 7A, the straight line connecting the crests 110 or the bottom surfaces 112 passes through the axial center O, so the outer diameter (maximum diameter) of the rotor teeth passing through the axial center O with a micrometer or the like. And measurement of root diameter was possible. On the other hand, in the cross section of the male rotor or the female rotor having the odd number of rotor teeth shown in FIGS. 7B and 7C, the crest 110 of the rotor tooth 106 and the tooth bottom 112 face each other across the axis O. Arrangement. Therefore, even if a micrometer or the like is used, the outer diameter (maximum diameter) and root diameter of the rotor tooth passing through the axis center O cannot be measured. Therefore, it is not possible to employ a processing method for processing the rotor teeth into a predetermined dimension while measuring the outer diameter and the root diameter of the rotor teeth with a micrometer or the like.

  Patent Document 2 discloses a measuring device that enables measurement of a tooth bottom surface of a rotor tooth with respect to a screw rotor mounted at a processing position of a processing machine in such a case. This measuring device is provided on a table of a processing machine and has a measuring unit having a measuring element that contacts and scans a measurement surface of a workpiece to be processed in a rotor groove, and a moving mechanism that moves the measuring unit forward and backward In the state where the measuring unit is stopped, the increase and decrease of the contact amount between the tooth bottom surface of the rotor tooth and the measuring element is measured by the differential transformer, and the tooth bottom surface is measured.

  However, this measuring device needs to be installed in advance on the table of the processing machine, so that the configuration of the table becomes complicated and the processing machine becomes expensive. In addition, there is a problem that it takes time to position the probe with respect to the tooth bottom surface. For this reason, the present inventors have performed the following processing method. First, the outer peripheral surface of the journal shaft part formed on both side parts sandwiching the rotor part forming part of the round bar material is processed so as to have the same diameter as the root diameter of the rotor teeth. Next, with the outer peripheral surface of the journal shaft portion as a reference surface, the rotor teeth are formed so that the root diameter of the rotor teeth matches the outer diameter of the journal shaft portion. Then, it cuts until the outer diameter of a journal axial part becomes a design dimension.

International Publication No. 2004-89569 JP-A-11-108653

  Since the journal shaft portion is supported by a slide bearing, the journal shaft portion needs to be hardened by quenching in order to prevent wear of the journal shaft portion. However, in the machining process with a round bar material, the journal shaft is processed to the same size as the rotor tooth root diameter, and this journaling method processes the journal shaft in two stages. There is a problem that increases. Further, since the journal shaft portion is processed after the rotor teeth are processed, it is impossible to continue the quench hardening treatment of the journal shaft portion that affects the size of the rotor teeth. For this reason, it is necessary to perform a hard chrome plating process that does not cause thermal distortion, and this is a separate process that deviates from the screw rotor processing line, resulting in an increase in cost, man-hours, and a long lead time.

  Moreover, since the finished dimension of a screw rotor cannot be measured directly, there exists a problem that measurement accuracy is not enough. In addition, since the screw rotor having an even number of rotor teeth can measure the outer diameter and the root diameter of the rotor teeth during cutting, it is necessary to use a casting material having a groove corresponding to the rotor groove as a material. did it. However, screw rotors with an odd number of rotor teeth cannot directly measure the outer diameter or root diameter of the rotor teeth, so it is unavoidable to use a round bar without a groove whose outer diameter is finished in advance. Expense was expensive. In an optical measuring means such as a laser length measuring device, a light beam such as a laser beam is reflected on the curved surface of the rotor tooth, making accurate measurement difficult.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and it is an object of the present invention to simplify and reduce the cost of processing a screw rotor having an odd number of rotor teeth and to reduce material costs.

In order to achieve this object , there is provided a method for processing a screw rotor having an odd number of rotor teeth, using a cylindrical casting material in which grooves are formed in advance in a portion corresponding to the rotor groove, and forming the rotor teeth of the casting material. by cutting a portion sandwiching the site, first formed a first step of forming a journal shaft portion in cross-section having an outer peripheral surface of a true circle, an odd number of rotor teeth the rotor teeth forming portion and the gear cutting rough machining and second step, after the second step, quenching the journal shaft portion, and a third step of processing subsequent finishing the journal shaft portion, a fourth step of finishing the rotor teeth and the rotor teeth outside diameter of the odd , in the second step and fourth step, a measuring step of a reference plane an outer circumferential surface of the journal shaft portion, for measuring the diameter of the outer peripheral surface of the rotor teeth from the relative positions of any of the outer peripheral surface of the rotor tooth relative to the reference plane The journal Prior to quenching of the shaft portion, cutting of the journal shaft portion and rough cutting of the portion where the rotor portion is formed, and then finishing the journal shaft portion and rotor teeth after quenching of the journal shaft portion. A method of processing a screw rotor having an odd number of rotor teeth.

  In the method of the present invention, before the journal shaft portion is quenched, the journal shaft portion is processed, and the rotor portion forming portion is subjected to rough cutting, thereby easily performing these operations without being affected by quenching. be able to. In addition, after the journal shaft portion is quenched, the journal shaft portion and the rotor teeth are finished, thereby eliminating the influence of quenching on the set dimensions of the journal shaft portion and the rotor teeth. And in the process which forms a rotor tooth, the diameter of the arbitrary outer peripheral surface of the rotor tooth in cutting can be directly measured by using the said measurement process together. Thereby, the rotor teeth can be processed with high accuracy.

  According to the method of the present invention, it is possible to eliminate the process of processing the journal shaft portion to an oversize, so that the number of processing steps of the journal shaft portion can be reduced. Further, since the journal shaft portion is quenched before the finishing of the rotor portion, the quenching does not affect the finished dimensions of the rotor teeth. Therefore, the hard chrome plating process is not necessary, and the cost can be reduced. Further, by measuring the relative position between the outer peripheral surface of the journal shaft portion and the cutting surface of the rotor tooth using the outer peripheral surface of the journal shaft portion as a reference surface, the diameter (outer diameter and (Including the root diameter) can be easily measured, and the rotor teeth can be processed with high accuracy.

  The measurement step includes a main body casing, a fixing base fixed to the main body casing and abutting on the outer peripheral surface of the journal shaft portion, attached to the main body casing so as to be able to advance and retreat, and a tip abutting on the outer peripheral surface of the rotor teeth. The diameter of the outer peripheral surface of the rotor tooth from the relative position of the measuring member built in the main body casing, the fixed base that is in contact with the outer peripheral surface of the journal shaft, and the measuring member that is in contact with the outer peripheral surface of the rotor tooth A measuring device having a detecting means for detecting (a diameter of an arbitrary outer peripheral surface including an outer diameter and a root diameter) and a display unit for displaying the diameter of the outer peripheral surface of the rotor tooth detected by the detecting means is used. Good.

  Using this measuring device, a first step in which the fixed base comes into contact with the outer peripheral surface of the journal shaft portion, a second step in which the measuring piece comes into contact with the outer peripheral surface of the rotor teeth, and the fixing base and the measuring piece in the circumferential direction of the screw rotor. And detecting the minimum value of the relative position between the fixed base and the measuring element as the root diameter of the rotor tooth and detecting the maximum value of the relative position as the outer diameter (maximum diameter) of the rotor tooth. And do it. By using this measurement step in combination with the second step and the fourth step, the diameter of the outer peripheral surface including the outer diameter and the root diameter of the rotor tooth being cut can be detected with high accuracy by a simple operation.

  Thus, in the method of the present invention, even for a screw rotor having an odd number of rotor teeth, the diameter of any outer peripheral surface including the outer diameter and the root diameter of the rotor teeth can be detected with high accuracy during the processing of the rotor teeth. it can. Therefore, it is possible to use a cylindrical casting material in which a groove is formed in a portion corresponding to a rotor groove as a round bar material, and material costs can be reduced.

Moreover, the measuring device used in the present invention is a measuring device that has the above-described configuration and can be directly used for carrying out the method of the present invention. The detecting means for detecting the diameter of the outer peripheral surface of the rotor tooth from the relative position between the fixed base and the measuring element generates a voltage value corresponding to the relative position as in the differential transformer disclosed in Patent Document 2, for example. What is necessary is just to obtain | require the said relative position by detecting this voltage value using the apparatus to do. Since the measuring device of the present invention is lightweight and can be miniaturized, it is easy to operate.

  According to the present invention, it is possible to simplify the machining process of a screw rotor having an odd number of rotor teeth, reduce costs, and reduce material costs.

It is explanatory drawing which shows the male rotor (after a process) which comprises a screw rotor. 1 is an overall view of a measuring apparatus according to an embodiment of the present invention. It is a front view which shows the measuring method using the said measuring device. It is a side view which shows the measuring method using the said measuring device. It is a flowchart which shows the process sequence of the male rotor which concerns on one Embodiment of this invention method. It is a flowchart which shows the processing procedure of the conventional male rotor. (A)-(C) are sectional drawings which show the various shapes of a screw rotor.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

  An embodiment of the present invention will be described with reference to FIGS. This embodiment is an example in which the present invention is applied to processing of a male rotor having five rotor teeth. FIG. 1 is an overall view of a male rotor 10 after processing in the present embodiment. In FIG. 1, journal shaft portions 20 and 22 having outer peripheral surfaces having a perfect cross section are formed integrally with the rotor tooth forming portion 12 at both axial ends of the rotor tooth forming portion 12. A drive shaft 24 is integrally formed on the end surface of the journal shaft portion 22 coaxially, and the drive shaft 24 is rotationally driven by a drive motor (not shown) after being assembled to a screw compressor, for example.

As shown in FIGS. 2 and 3, the cross sections of the outer peripheral surfaces of the journal shaft portions 20 and 22 are perfectly circular, and the cross-sectional center O ′ of the journal shaft portions 20 and 22 and the cross-sectional center O of the rotor portion 12 are overlap. The rotor 12, five rotor teeth 14 are machined in a spiral shape toward the axial direction is formed. The rotor tooth 14 has a peak portion 16 having a maximum diameter and a tooth bottom surface 18 having a minimum diameter.

In FIG. 2, the whole structure of the measuring device 30 used for this invention is shown. The measuring device 30 includes a main body casing 32, and a fixed base 34 is fixed to the main body casing 32. As shown in FIG. 4, the fixed base 34 is arranged in a position parallel to the central axis i of the main body casing 32 and deviated from the central axis i. A tubular cover 36 is attached to the main body casing 32 in parallel with the fixed base 34. The cover 36 is disposed on the central axis i of the main body casing 32 and is disposed substantially parallel to the fixed base 34. A measuring element 37 is accommodated in the cover 36. The measuring element 37 protrudes from the tip of the cover 36, and the measuring element 37 is detachably arranged with respect to the cover 36 and the main body casing 32.

  The end surface 34 a of the fixed base 34 is formed with a concave surface having a shape matching the outer peripheral surfaces of the journal shaft portions 20 and 22 so that the fixed base 34 can be easily fixed to the outer peripheral surfaces of the journal shaft portions 20 and 22. The body casing 32 incorporates a detection device 38 that detects the relative position between the fixed base 34 (more precisely, the end surface 34 a) and the measuring element 37 when detecting the diameter of the outer peripheral surface of the rotor tooth 14. For example, like the differential transformer disclosed in Patent Document 2, the detection device 38 converts the relative position of the fixed base 34 and the measuring element 37 into a signal, and detects the relative position from the signal. The detection device 38 calculates the diameter of the outer peripheral surface including the peak portion 16 and the tooth bottom surface 18 of the rotor tooth 14 from the detected value.

  The main body casing 32 and the digital counter 42 are connected by a cable 40, and the digital counter 42 is connected by a cable 44 to a power supply device (not shown). The diameter of the cutting surface including the crest 16 and the root surface 18 of the rotor tooth 14 detected by the detection device 38 is displayed on the display unit 42 a of the digital counter 42.

  In such a configuration, the male rotor 10 is processed from a casting material by the processing procedure shown in FIG. As the casting material, a cylindrical casting material in which a groove is formed in advance in a portion corresponding to the rotor groove can be used. In FIG. 5, the casting material is mounted on a lathe, and the parts corresponding to the journal shafts 20 and 22 and the drive shaft 24 are turned (S10). At this stage, the outer diameters of the journal shafts 20 and 22 processed into a cylindrical shape are processed into the process design dimensions. Next, the casting material is mounted on a rotor processing machine (gear cutting machine), and rough cutting of the rotor tooth forming portion 12 is performed (S12).

  In the male rotor 10 incorporated in the screw compressor, the journal shaft portions 20 and 22 are supported by a housing of the screw compressor via a sliding bearing. Therefore, next, the journal shaft portions 20 and 22 are subjected to induction hardening and strain relief heat treatment to increase the strength of the journal shaft portion (S14). Thereafter, finish grinding of the journal shaft portions 20 and 22 is performed with a grinding machine (S16). The outer peripheral surfaces of the finished journal shaft portions 20 and 22 serve as a reference surface for detecting the diameter of the outer peripheral surface of the rotor tooth 14. The dimension of the reference surface is measured with a micrometer or the like and input to the digital counter 42.

Next, the male rotor 10 is mounted on a rotor processing machine, and the rotor gear 14 is subjected to rotor gear cutting finishing processing while measuring the root diameter of the rotor tooth 14 using the measuring device 30. Next, the male rotor 10 is mounted on a grinding machine, and grinding finish processing is performed in order to set the outer diameter of the rotor tooth to a completed dimension while measuring the outer diameter of the rotor tooth using the measuring device 30 (S18). Hereinafter, referring to FIG. 3 and FIG. 4, illustrating a measuring method using the measuring apparatus 30.

  3 and 4, the outer peripheral surface of the journal shaft portion 22 after finishing is set as a reference height, and an operator abuts the end surface 34 a of the fixed base 34 on the outer peripheral surface of the journal shaft portion 22. In this state, the main body casing 32 is disposed perpendicular to the outer peripheral surface of the journal shaft portion 22. That is, the main body casing 32 is positioned so that the center axis i passes through the center O ′ of the journal shaft portion 22 (the cross-sectional center O of the rotor tooth forming portion 12). Next, the probe 37 is brought into contact with the outer peripheral surface of the rotor tooth 14. In this state, the relative position between the fixed base 34 and the measuring element 37 is measured by the detection device 38. The diameter of the outer peripheral surface of the rotor tooth 14 with which the measuring element 37 is in contact can be detected from this measured value and the dimension of the reference surface of the journal shafts 20 and 22 input in advance to the digital counter 42. The detected diameter of the outer peripheral surface is displayed on the display unit 42 a of the digital counter 42.

  Next, in a state where the fixed base 34 is in contact with the outer peripheral surface of the journal shaft portion 22 and the measuring element 37 is in contact with the outer peripheral surface of the rotor tooth 14, the fixing base 34 and the measuring element 37 are connected to the journal shaft portion 22 and the rotor. The tooth 14 is moved in the circumferential direction. During movement, the position where the detected value is minimized is the root surface 18, and the minimum value is the root diameter of the rotor tooth 14. The maximum position is the peak 16 and the maximum value is the outer diameter of the rotor tooth 14. On the journal shaft 20 side, the outer peripheral surface of the rotor tooth 14 is measured in the same procedure. In this way, the tooth cutting roughing (S12) and finishing (S18) of the rotor teeth 14 are performed while measuring the outer peripheral surface of the rotor teeth 14 at both ends of the rotor tooth forming portion 12.

  Next, after the male rotor 10 is finished to the design dimensions by the rotor gear cutting and the rotor tooth outer diameter finishing process (S18), the meshing inspection with the separately processed female rotor is performed (S20). From this inspection result, the rotor teeth 14 are corrected according to circumstances. Next, the final finishing of the journal shaft portion 22 is performed with a lathe and a grinding machine (S22). Thereafter, the male and female screw rotors are completed through balance processing (S24) for improving the balance state of the male and female screw rotors and completion inspection (S26).

  According to the present embodiment, the processing time of the journal shaft portions 20 and 22 can be greatly shortened as compared with the conventional oversize processing method, so that the man-hours for processing the journal shaft portions can be reduced. In addition, since the rotor teeth 14 are rough-cut after the journal shaft portion is processed, the journal shaft portion can be quenched at an early stage after the journal shaft portion is processed. This eliminates the need for a hard chrome plating process with a long lead time, eliminates the time lag, and further enables the machining man-hours to be further reduced since the male rotor 10 can be completed after quenching.

  Furthermore, the rotor tooth 14 can be machined using the measuring device 30 while measuring the diameter of any outer peripheral surface of the rotor tooth 14 including the root diameter, using the outer peripheral surfaces of the journal shaft portions 20 and 22 as a reference surface. Therefore, even when the rotor teeth 14 are odd teeth, the rotor teeth 14 can be processed with high accuracy. Further, since the handy measuring device 30 is used, the operation of the worker is easy. Further, even when the rotor teeth 14 are odd-numbered teeth, a cast material with a groove can be used, so that the material cost and the processing man-hour can be further greatly reduced.

  FIG. 6 shows, as a comparative example, a processing method for a male rotor having five rotor teeth, which has been conventionally performed by the present inventors. Conventionally, a grooved round bar material cannot be used, and a grooved round bar material is used. First, a round bar material is mounted on a lathe and the journal shafts 20 and 22 are machined (S30). Next, the male rotor 10 is mounted on a grinding machine, and the shaft shaft 20 and 22 are ground until the outer diameter of the journal teeth 20 and 22 is adjusted to the bottom surface of the rotor teeth 14. A grinding process for finishing is performed (S32). Next, the rotor tooth forming portion 12 is subjected to rough cutting by a rotor processing machine, and the bottom surface of the rotor tooth 14 is adjusted to the outer diameter of the journal shaft portions 20 and 22 (S34). In S32, a lot of processing time is required to grind the entire circumference of the rotor forming portion of the round bar material.

  The male rotor 10 thus processed is removed from the rotor processing machine, and a meshing inspection is performed to check the meshing state with the separately processed female rotor (S36). Next, the male rotor 10 is mounted on a lathe, and the journal shafts 20 and 22 are machined to design dimensions (S38). Here, the journal shaft portions 20 and 22 are removed from the lathe, and the lower processing for plating processing (S40) and the hard chrome plating processing (S42) are performed. Thereafter, the male rotor 10 is mounted on the lathe again, and finishing of the journal shaft portions 20 and 22 after plating is performed (S44). Then, a male-female screw rotor is completed through balance processing (S46) and completion inspection (S48).

  In the conventional processing method, since the journal shaft portions 20 and 22 are processed in two stages, the number of processing steps increases. Further, finishing of the journal shaft portion must be performed after the processing of the rotor teeth 14, and therefore, quenching of the journal shaft portion that affects the finished dimensions of the rotor teeth 14 cannot be employed. Therefore, a hard chrome plating process is required, and the screw rotor must be taken out of the processing line to perform the hard chrome plating process, resulting in problems such as an increase in cost, man-hours, and a long lead time.

  In addition, since the finished dimensions of the screw rotor cannot be directly measured, it has been impossible to use a slim casting material shape or a grooved casting material as a material in which measurement accuracy cannot be sufficiently secured. Therefore, the material cost is expensive. The present inventors used the processing time of the male rotor required in the above embodiment (when using a cast material with a groove) and the processing time of the male rotor required in the conventional processing method (using a grooveless round bar material). The machining time of this embodiment can be reduced by 7.5 hours per male rotor from the conventional machining time.

  When a screw rotor cannot be supported by a ball bearing or a roller bearing in a medium-sized and large-sized screw compressor, it is necessary to use a sliding bearing, but the present invention is suitable for processing such a medium-sized and large-sized screw rotor.

  ADVANTAGE OF THE INVENTION According to this invention, while processing the screw rotor which has an odd number of rotor teeth, and cost reduction, material cost can be saved.

DESCRIPTION OF SYMBOLS 10,102 Male rotor 12 Rotor tooth formation site 14,106,108 Rotor tooth 16,110 Mountain part 18,112 Tooth base 20,22 Journal shaft part 24 Drive shaft 30 Measuring device 32 Main body casing 34 Fixing base 36 Cover 37 Measuring element 38 Detection Device 40, 44 Cable 42 Digital Counter 42a Display Unit 100 Screw Rotor 104 Female Rotor

Claims (2)

It is a processing method of a screw rotor having an odd number of rotor teeth , using a cylindrical casting material in which grooves are formed in advance in portions corresponding to rotor grooves,
By cutting a portion sandwiching the rotor teeth forming portion of the cast material, a first step of forming a journal shaft portion in cross-section having an outer peripheral surface of a perfect circle, odd the rotor teeth forming portion and the gear cutting rough machining a second step of forming the rotor teeth, after the second step, quenching the journal shaft portion, and a third step of processing subsequent finishing the journal shaft, the rotor teeth and the rotor teeth outside diameter of the odd a fourth step of finishing, in the second step and fourth step, the journal shaft portion outer circumferential surface as a reference plane, from the relative position of any of the outer peripheral surface of the rotor tooth relative to the reference surface of the outer peripheral surface of the rotor tooth A measuring process for measuring the diameter ;
Prior to quenching of the journal shaft, the journal shaft is cut and roughed at the portion where the rotor is formed, and after the journal shaft is quenched, the journal shaft and rotor teeth are finished. A method for processing a screw rotor having an odd number of rotor teeth. The measurement step includes
A main body casing, a fixed base fixed to the main body casing and abutting on the outer peripheral surface of the journal shaft, and a measuring element attached to the main body casing so as to be able to advance and retreat and having a tip abutting on the outer peripheral surface of the rotor tooth And detecting the outer diameter of the rotor tooth from the relative position of the fixed base built in the main body casing and in contact with the outer peripheral surface of the journal shaft portion and the measuring element in contact with the outer peripheral surface of the rotor tooth. Using a measuring device comprising a detection means and a display unit that displays the diameter of the outer peripheral surface of the rotor tooth detected by the detection means,
A first step of contacting the fixed base to the outer peripheral surface of the journal shaft;
A second step of contacting the probe with the outer peripheral surface of the rotor tooth;
The fixed base and the measuring element are moved in the circumferential direction of the screw rotor, and the minimum value of the relative position is detected as the root diameter of the rotor tooth, and the maximum value of the relative position is detected as the outer diameter of the rotor tooth. The screw rotor processing method according to claim 1, wherein the third step is performed.

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