Equal-wall-thickness screw motor and manufacturing method thereof

Abstract

The invention relates to the technical field of roller bits, in particular to an equal-wall-thickness screw motor which comprises an equal-wall-thickness stator, the inner wall of the equal-wall-thickness stator is provided with a linear structure, and equal-thickness rubber is arranged on the linear structure. The engineering plastic is used for injection molding, and after molding, the strength is high, the hardness is high, and the bearing performance is high.

Description

Technical Field

[0001] The invention relates to the technical field of roller drill bits, in particular to a uniform wall thickness screw motor and a manufacturing method thereof. Background Art

[0002] Conventional motors such as Figure 3 However, the main problem in use is the damage of the rubber. On the one hand, the rubber is uneven in thickness. When the rotor 8 rotates, the rubber 7 is always subjected to the shearing effect of the rotor. The rotor 8 and the rubber 7 have a certain amount of interference fit, and a sealing line is generated by the interference fit. However, during the rotation process, heat is easily accumulated in the thick part of the rubber, and the core is overheated, causing the rubber to lose its elasticity, which eventually manifests as the rubber failing and falling off.

[0003] Similarly, due to the long size of the stator and rotor, the processing accuracy cannot perfectly ensure that the streamlines at each position strictly conform to the designed geometric lines. Therefore, it is very likely that the local interference will be too large, and the local force will be too large when the motor is running, and the rubber will fail over time. Summary of the invention

[0004] In order to effectively solve the problems in the above-mentioned background technology, the present invention proposes a screw motor with uniform wall thickness and a manufacturing method thereof.

[0005] The specific technical solutions are as follows:

[0006] A screw motor with constant wall thickness comprises a stator with constant wall thickness. The inner wall of the stator with constant wall thickness has a linear structure, and rubber with constant thickness is arranged on the linear structure.

[0007] A screw motor with equal wall thickness comprises a stator with equal wall thickness, wherein an engineering plastic layer is fixed to the inner wall of the stator with equal wall thickness, a linear structure is arranged on the inner wall of the engineering plastic layer, and rubber with equal thickness is arranged on the linear structure.

[0008] A method for manufacturing a screw motor with uniform wall thickness comprises the following steps: step 1, fixing a stator with uniform wall thickness on a device; step 2, installing a core rod with a linear structure inside the stator with uniform wall thickness; step 3, injecting engineering plastic between the core rod and the stator with uniform wall thickness, and cooling to form an engineering plastic layer; step 4, placing a glue injection core shaft into the engineering plastic layer, and then injecting rubber to form a rubber layer.

[0009] Preferably, an adhesive is filled between the equal-thickness stator and the engineering plastic layer.

[0010] Compared with the prior art, the invention has the following beneficial effects: the invention uses engineering plastics for injection molding, which has high strength, high hardness and strong load-bearing performance after molding. The stator rubber with equal wall thickness is more evenly stressed and heated, and the rubber is thinner as a whole. At the same time, due to the support of metal wire type, it can withstand higher pump pressure, output torque is also higher, the speed is fast, the output is high, and it is a screw motor with long efficiency and life. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the mainstream structure of screw drilling tools;

[0012] Figure 2 It is a schematic diagram of the stator tube mechanism;

[0013] Figure 3 is a cross-sectional view of the motor assembly;

[0014] Figure 4 is the rotor diagram;

[0015] Figure 5 This is a schematic diagram of a motor with equal wall thickness;

[0016] Figure 6 This is a schematic diagram of the motor after molding;

[0017] Figure 7 This is a schematic diagram of engineering plastic injection molding equipment;

[0018] Figure 8 for Figure 7 A magnified image of

[0019] Fig. 9 for Figure 8 Cross-sectional view of the assembled stator after injection;

[0020] Fig.10 is a cross-sectional view of the stator;

[0021] Fig.11 Cross-sectional views of stators of different shapes. DETAILED DESCRIPTION

[0022] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways, rotated 90 degrees or in other orientations, and the spatially relative descriptions used herein are interpreted accordingly.

[0023] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments. Figure 1 As shown, the present invention proposes a screw motor with equal wall thickness, and the mainstream structure of the screw drill is shown in Figure 1 , where 1 is the bypass valve assembly, 2 is the anti-drop assembly, 3 is the motor assembly, 4 is the universal shaft assembly, and 5 is the transmission shaft assembly. The bypass valve assembly 1 is mainly used to switch the mud. When the mud pump is turned on, the hole in the circumferential direction of the bypass valve is closed. When the mud pump is turned off, the circumferential hole is opened to discharge the remaining mud in the screw. The main function of the anti-drop assembly 2 is to prevent the connection between the major assemblies below and the internal shafts from being disconnected or damaged, and to prevent falling into the well. For example, when the thread of the shell is broken by force during use, the internal anti-drop rod will pull the lower part and hang on the step inside the anti-drop shell. The function of the motor assembly 3 is to generate power. Special rubber is attached to the inside of the steel pipe. The rubber is injection molded through a linear core shaft and cooperates with the rotor with the same linear shape to convert the mud injected by the mud pump into energy and convert the hydraulic energy into kinetic energy. The internal rotor will rotate under the drive of the hydraulic pressure, and its rotation is planetary rotation. Then the universal shaft assembly 4, in which both ends of the universal shaft have joints, convert the planetary motion into centering rotation, and the outer shell has a certain angle of curvature, which can be used for directional drilling or deflection drilling. The transmission shaft assembly 5 has a pressure bearing and a radial wear-resistant bearing inside, which plays a role in bearing the drilling pressure.

[0024] Figure 2 For the stator tube Figure 1 The outer shell of the steel tube in the middle 3 parts has an inner hole rubber, 6 is the stator tube, and 7 is the rubber with spiral lines.

[0025] Figure 3It is a cross-sectional view of the motor assembly 3, 6 is the stator outer shell, which is generally made of alloy steel. 7 is the rubber with a spiral line made inside the stator. 8 is the rotor, and the rotor material is also steel, which is machined into a linear shape by a multi-axis milling machine or the like. It can be observed that 9 is the linear protrusion on the rotor 8, and 10 is the linear depression on the stator rubber 7. The lines 9 and 10 match, but it can be observed that the number of the rubber linear depression 10 is one more than the rotor linear protrusion 9. The purpose is to form a sealed cavity by the flow of mud through the gap, generate a hydraulic driving force, and make the rotor 8 perform planetary rotation inside the stator rubber 7. For specific design concepts, please refer to the relevant screw drilling tool principle literature.

[0026] Figure 4 That is, the rotor 8 has a linear profile through milling or other processing methods, and the linear profile achieves different rotation speeds and torque outputs through different leads.

[0027] The so-called constant wall thickness motor Figure 5 , it can be observed that different from Figure 3 The designed linear shape is directly processed on the inner wall of the steel pipe, and then the glue is injected to form a motor stator 11 with equal wall thickness. Figure 6 .

[0028] Figure 6 It can be seen that on the linear stator 11 with uniform wall thickness, a rubber 12 of uniform thickness is attached. The rubber can be modified nitrile rubber in a general environment, or hydrogenated nitrile rubber in a high temperature environment. The thickness of the rubber 12 is the same at all positions, which is different from Figure 3 The rubber is of uneven thickness, and the stator rubber with equal wall thickness is more evenly stressed and heated. The rubber is thinner overall. At the same time, due to the support of metal wires, it can withstand higher pump pressure and output higher torque. It has fast speed and high output. It is a screw motor with long efficiency and life.

[0029] However, the processing of stators with equal wall thickness is very time-consuming and the corresponding cost is also very high. The common processing methods include electrochemical corrosion processing (ECM). Electrochemical processing requires the production of a large machine tool, using pre-processed linear electrodes, and electrolyte, generally Nacl or NaOH solution, and a large water tank. A high-pressure pump is used to spray the electrolyte into the gap between the tube body and the electrode. At the same time, the CNC system and the power supply coordinate the discharge and movement. This type of machine tool occupies a very high area and investment. Another prerequisite is high-precision steel pipes. The coaxiality of the raw material steel pipe is high. Generally, a 5-meter-long steel pipe with a wall thickness of 50mm requires an overall internal and external concentricity of ≤0.5mm and an overall curvature of ≤0.5mm. In addition, the maintenance of the electrolyte, the subsequent electrolytic sediment filtration and cleaning system, the sediment pressure filtration after cleaning, the liquid recycling and the main energy consumption of electricity, the production cost of a stator with equal wall thickness requires 10,000 to tens of thousands of yuan. Taking a 5-meter steel pipe as an example, the production time varies from 24 to 40 hours.

[0030] Another method is to use machining methods, such as broaching or milling machines for deep hole processing, which is also very slow and time-consuming. It is equipped with a wide variety of linear cutter heads. The production of motors with equal wall thickness is a very complicated task.

[0031] The present invention uses a new method to manufacture an efficient, fast and low-cost equal-wall-thickness motor to meet the requirements of equal-wall-thickness.

[0032] Engineering plastics are products with high mechanical properties, high temperature resistance, chemical solvent corrosion resistance, and excellent thermal stability. Their excellent rapid prototyping capabilities have obvious advantages in industrial production. Common engineering plastics include polyetheretherketone (PEEK), polyphenylene sulfide (PPS), and PA46 (polybutylene oxadiamine).

[0033] The selection of the above engineering plastics is more based on the use conditions and the design of the screw drill itself. The above types of plastics are only examples and are not limited thereto. The present invention mainly uses engineering plastics that can be injection molded. After molding, they have high strength, high hardness, and good load-bearing performance, and are used to make stators with equal wall thickness.

[0034] Figure 7 and Figure 8It is a schematic diagram of engineering plastic injection molding. The injection molding type shown in the figure is a worm type. Of course, it can be a press or other types, not limited to a worm injection molding machine. The raw material tank 13 is used to hold the raw materials of engineering plastics, which may have a heating and heat preservation function, such as polyetheretherketone. The heated state is slurry, or it has heating at the injection position. The raw materials can be loaded in powder or granular form, etc., depending on the design of the equipment, not limited to a certain form. The hydraulic propulsion device 14 is the power source for injection. The worm 15 is used to propel the slurry into the locking device 16 of the stator tube. The engineering material layer 17 after injection, the core rod 18 has a linear shape, so the engineering plastic layer 17 after injection also has a linear shape.

[0035] The inner wall of the stator tube 6 and the engineering plastic layer 17 can be bonded with a corresponding adhesive to ensure bonding strength. Commonly used adhesives are slurry-like, such as some models of Parker Lord products. Products that can be bonded with suitable engineering plastics can be selected.

[0036] Figure 8 This is an illustration of the core rod installation, which only explains this design. Locking devices such as injection ports are designed, but it is not limited to this design.

[0037] Fig. 9 for Figure 8 In the cross-sectional view of the assembled stator after injection, it can be seen that the engineering plastic forms the required linear shape after injection under the action of the core mold. After cooling, the engineering plastic hardens and replaces the conventional metal linear shape with the same wall thickness. In actual work, it plays a supporting role and makes the subsequent rubber wall thickness the same.

[0038] After the engineering plastic hardens, it is assembled using a glue injection mandrel and injected with rubber. Rubber injection is a common process for screw drills. The injection equipment is similar to the injection tooling. Figure 7 There are worm-type injection equipment and press-type equipment that can directly inject. Any equipment that can meet the needs will be sufficient. The conventional process will not be described in detail. The interface between engineering plastics and rubber is also bonded with a suitable adhesive. The adhesive type is also taken as an example of a certain type of Parker Lode Company. Any suitable one can be used. After the injection is completed and the mandrel is removed, the cross section of the stator can be seen. Fig.10 .

[0039] From the screenshot after completion, it can be seen that the engineering plastic 17 injected into the stator tube 6 becomes a linear skeleton with equal wall thickness. Its high mechanical properties and curing molding capabilities can meet the needs. The same process can be used to produce screws with equal wall thickness for various design requirements, such as changing the lead and number of heads of the screw line. Fig.11 This is an illustration of the change in the number of heads. The lead change is achieved through the design of the core shaft, which will not be elaborated on.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A screw motor with equal wall thickness, characterized in that: The invention comprises a stator with a constant wall thickness, wherein the inner wall of the stator with a constant wall thickness has a linear structure, and rubber with a constant thickness is arranged on the linear structure.

2. A screw motor with equal wall thickness, characterized in that: The invention comprises a stator with equal wall thickness, wherein an engineering plastic layer is fixed on the inner wall of the stator with equal wall thickness, a linear structure is arranged on the inner wall of the engineering plastic layer, and rubber with equal thickness is arranged on the linear structure.

3. A method for manufacturing a screw motor with uniform wall thickness, characterized in that: Step 1, fix the stator with equal wall thickness on the equipment; Step 2, install the core rod with linear structure into the stator with equal wall thickness; Step 3, inject engineering plastic between the core rod and the stator with equal wall thickness, and cool to form an engineering plastic layer; Step 4, put the injection core shaft into the engineering plastic layer, and then inject rubber to form a rubber layer.

4. The method for manufacturing a screw motor with equal arm thickness according to claim 3, characterized in that: Adhesive is filled between the equal-thickness stator and the engineering plastic layer.

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