Integrated injection molding commutator and processing technology thereof

Abstract

The invention discloses an integrated injection molding commutator and a processing technology thereof, and the commutator mainly comprises commutator segments, mica sheets, insulating bushings, a pressing hoop A and a pressing hoop B. When the commutator is subjected to injection molding, commutator composition materials, a molding mold and engineering plastic particles which are needed to be used are prepared. The preparation method comprises the following steps: performing embedding installation on prepared commutator composition materials, closing and locking a mold under high pressure after the embedding installation of the materials is completed, melting and uniformly mixing dried plastic granules in a charging barrel of an injection molding machine through shearing heat generated by heating and rotation of a screw rod to form a viscous-flow-state melt, and in a molten state, performing extrusion molding on the molten plastic granules to obtain the commutator. The screw is driven by an oil cylinder to advance forwards at a high speed, melt is injected into a closed mold cavity at high pressure, after cooling is completed, the mold is opened, an ejection mechanism acts, a solidified commutator product is stably pushed out of the mold cavity, pouring gate aggregate and flash burrs on the commutator product are removed, and heat treatment is conducted on the machined commutator.

Description

Technical Field

[0001] The present invention relates to the technical field of commutator processing, in particular to an integral injection-molded commutator and a processing technology thereof. Background Art

[0002] The commutator usually refers to the key rotating component in a DC motor (or DC generator). Its core function is to convert external DC power into AC power inside the armature winding (for motors), or to convert AC power inside the winding into external DC power (for generators). Its structure usually consists of the following main parts:

[0003] Commutator segment:

[0004] Material: Usually made of copper because copper has good conductivity and wear resistance.

[0005] Shape: Multiple copper sheets with wedge-shaped (trapezoidal) cross-sections.

[0006] Quantity: The quantity is related to the number of coils (or elements) in the armature winding and the number of poles in the motor.

[0007] Function: Each commutator segment is welded to the end of one (or a group of) coil elements in the armature winding. Brushes slide on the surface of these commutator segments, achieving electrical connection and commutation between the external circuit and the rotating armature winding.

[0008] Surface: The working surface needs to be very smooth, flat, and maintain good cylindricity to reduce brush wear and sparking.

[0009] Mica flakes:

[0010] Material: Made of mica (or synthetic mica with better performance, high temperature resistant insulation material).

[0011] Shape: Wedge-shaped (trapezoidal) insulating segments that match the shape of the commutator segments.

[0012] Position: Sandwiched between adjacent commutator segments.

[0013] Function: Provides electrical insulation, preventing short circuits between adjacent commutator segments. Mica offers excellent electrical insulation, high-temperature resistance, and mechanical strength. Other high-performance insulating materials are sometimes used in small motors.

[0014] Clamping device:

[0015] Composition: Mainly includes V-shaped pressure ring (also called dovetail ring, tapered ring) and sleeve (or pressure ring).

[0016] Material: Usually made of steel, with sufficient strength and rigidity.

[0017] Structure: The tail of the commutator segment (the non-working end) is also processed into a corresponding V-shape (dovetail shape). Two V-shaped pressure rings (one in front and one in the back) are sleeved on the V-shaped dovetail groove of the commutator segment group.

[0018] Function: Bolts or nuts pull the two V-shaped pressure rings toward each other, creating a powerful radial pressure through the tapered surface. This compresses the entire commutator segment assembly (including the commutator segments and mica sheets) into a solid unit. This pressure must be sufficient to prevent the commutator from loosening, deforming, or causing "flying segments" under high-speed rotation and high temperatures. The sleeve supports and positions the pressure ring.

[0019] Heat dissipation:

[0020] Form: Ventilation slots or heat dissipation ribs / fins are designed inside or at the ends of the commutator segment group.

[0021] Function: Helps dissipate the heat generated by current and friction during commutator operation, preventing overheating that can lead to insulation aging, deformation, or commutation deterioration. This is especially important for large motors.

[0022] Related parts that need to be distinguished (not part of the commutator body, but work closely with it):

[0023] Brush:

[0024] Conductive blocks made of materials such as graphite or metallic graphite.

[0025] The brush holder is pressed by a spring against the surface of the commutator to make sliding contact.

[0026] Responsible for directing current from the external stationary circuit into / out of the rotating commutator segments.

[0027] Brush Holder:

[0028] The bracket that fixes the brush ensures that the brush is pressed against the commutator in the correct position and angle, and can maintain appropriate pressure (usually provided by a spring), allowing the brush to wear within a certain range.

[0029] The use of commutators is very common. As one of the important components of motors, commutators are currently produced by assembling their components. This greatly reduces the stability of such commutators in the later stages. Therefore, an improved technology is urgently needed to solve this problem in the existing technology. Summary of the Invention

[0030] The purpose of the present invention is to provide a one-piece injection molded commutator and its processing technology using perfect one-piece injection molding to ensure that the completed commutator body 1 has strong integrity, good moisture absorption balance of the commutator, and good balance performance of the commutator, so as to solve the problems raised in the above background technology.

[0031] To achieve the above-mentioned object, the present invention provides the following technical solution: a processing technology for an integral injection-molded commutator, comprising the following steps:

[0032] S1. Prepare the commutator component materials, molding molds, and engineering plastic particles required for injection molding of the commutator body;

[0033] S2. Install the prepared commutator components by inserting them and pre-treating the engineering plastics;

[0034] S3. After the material is inserted and installed, the mold is closed and locked under high pressure to form a closed cavity. The clamping force must be large enough;

[0035] S4. The dried plastic pellets are melted and mixed evenly in the barrel of the injection molding machine through the shear heat generated by heating and screw rotation, becoming a viscous melt;

[0036] S5. In the molten state, the screw is driven forward at high speed by the cylinder, injecting the melt into the closed mold cavity at high pressure. The injection speed and pressure need to be precisely controlled to ensure that the cavity is filled quickly, smoothly and completely.

[0037] S6: The melt gradually loses heat under the action of the mold cooling system (circulating cooling water / oil), changing from a viscous flow state to a solid state. The cooling time accounts for most of the entire molding cycle (about 60-80%).

[0038] S7. After cooling is completed, the mold opens and the ejector mechanism operates to smoothly push the solidified commutator product out of the mold cavity.

[0039] S8. Remove the gate solids and burrs on the finished commutator product, and perform heat treatment on the processed commutator.

[0040] Preferably, the commutator body is provided with commutator segments, mica sheets, and insulating bushings. The commutator segments and mica sheets are arranged alternately. The clamping groove on one side of the commutator segment is provided with a clamping hoop A and a clamping hoop B. The clamping hoop A and the clamping hoop B are installed in cooperation with the commutator segments and the insulating bushings.

[0041] The commutator segment is L-shaped, and a clamping groove is provided on one side wall of the commutator segment.

[0042] The outer wall of the insulating bushing is provided with a clamping convex rib.

[0043] Preferably, in step S2, the commutator segments, mica sheets, and insulating bushings are precisely arranged and combined according to design requirements;

[0044] Accurately place the pre-assembled commutator segments, mica sheets, and insulating bushings on the positioning device of the mold;

[0045] Use manual installation or automated robotic arm installation. After placement, confirm whether the insert is fully in place and not loose.

[0046] Preferably, the engineering plastic in step S2 is PBT (polybutylene terephthalate), and the engineering plastic is fully dried in a dehumidifier before injection molding. The drying temperature is about 120-150° C. and the drying time is 4-6 hours. During the drying process, the dehumidifier continuously turns the engineering plastic.

[0047] Preferably, the mold must be provided with a high-precision and reliable positioning device to ensure that the commutator segment assembly does not move or deform during the mold closing and injection molding process.

[0048] Preferably, the molten PBT (polybutylene terephthalate) is injected into the mold cavity at a pressure of 80-150 MPa;

[0049] After the cavity is filled, the screw maintains a certain pressure (holding pressure, usually slightly lower than the injection pressure) and continues to slowly add material into the cavity.

[0050] The one-piece injection-molded commutator according to claim 1 is characterized in that: in step S8, manual deburring or mechanical borax treatment is used for deburring, and after deburring, the commutator is subjected to a hot water bath or steam humidity control treatment to remove powder on the commutator surface.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) Precisely place the pre-assembled commutator segments, mica sheets, and insulating bushings on the positioning device of the mold, and install them manually or with an automated manipulator. After placement, confirm whether the inserts are fully in place and not loose, to ensure smooth operation during the subsequent injection molding process and ensure that the structure of the injection-molded commutator fully meets the standards;

[0053] (2) Before injection molding, the engineering plastics are fully dried in a dehumidifier at a drying temperature of about 120-150°C for 4-6 hours. During the drying process, the dehumidifier continuously turns the engineering plastics to effectively avoid bubbles, silver streaks, and surface defects in the injection molded parts, which seriously affect the mechanical and electrical properties.

[0054] (3) Accurately replicate the final shape of the commutator, including the plastic body and the space for accommodating the inserts. The mold must have a high-precision, reliable positioning device to ensure that the commutator segment group will not move or deform during the mold closing and injection molding process.

[0055] (4) The melt gradually loses heat in the mold cooling system under the action of circulating cooling water / oil, and changes from a viscous flow state to a glassy or crystalline state. The cooling time accounts for 60-80% of the entire molding cycle. Sufficient cooling is the key to ensuring the stability of product dimensions, sufficient strength for ejection, and reducing deformation. Cooling must be uniform, otherwise it will cause internal stress, warping and other problems;

[0056] (5) After cooling is completed, the mold is opened and the ejection mechanism is activated to smoothly push the solidified commutator product out of the mold cavity, remove the gate condensate and possible flash burrs on the product, and use manual deburring or mechanical borax treatment to remove the burrs. After deburring, the commutator is placed in a hot water bath or steam humidity control treatment to remove the powder on the commutator surface and allow the commutator to reach a moisture balance state;

[0057] (6) The structure of the commutator body is simple and adopts perfect one-piece injection molding, so that the overall stability of the completed commutator body is good, the moisture absorption balance state of the commutator is good, and the balance performance of the commutator is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of the commutator processing process of the present invention;

[0059] Figure 2 This is a schematic structural diagram of the commutator body of the present invention;

[0060] Figure 3 A top view of the commutator of the present invention;

[0061] Figure 4 is a cross-sectional view of the commutator of the present invention;

[0062] Figure 5 This is a schematic diagram of the commutator segment structure of the present invention;

[0063] Figure 6 This is a schematic diagram of the insulating bushing structure of the present invention.

[0064] In the figure: 1. Commutator body; 2. Commutator segments; 3. Mica sheets; 4. Insulating bushings; 5. Clamping hoop A; 6. Clamping hoop B. DETAILED DESCRIPTION

[0065] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0066] See also Figures 1-6 The present invention provides a technical solution: a processing technology for an integrated injection-molded commutator: preparing the commutator component materials, molding molds, and engineering plastic particles required for injection molding of the commutator body 1, inserting and installing the prepared commutator component materials, and pre-treating the engineering plastics. After the material inserting and installation are completed, the mold is closed and locked under high pressure to form a closed cavity, and the clamping force must be large enough.

[0067] The dried plastic pellets are melted and mixed evenly in the barrel of the injection molding machine through heating and the shear heat generated by the rotation of the screw, becoming a viscous melt.

[0068] In the molten state, the screw is driven forward at high speed by the cylinder, injecting the melt into the closed mold cavity at high pressure. The injection speed and pressure need to be precisely controlled to ensure that the cavity is filled quickly, smoothly and completely.

[0069] The melt gradually loses heat under the action of the mold cooling system (circulating cooling water / oil), changing from a viscous flow state to a solid state. The cooling time accounts for most of the entire molding cycle (about 60-80%).

[0070] After cooling is completed, the mold opens and the ejector mechanism operates to smoothly push the solidified commutator product out of the mold cavity.

[0071] Remove the gate solids and burrs on the finished commutator product, and perform heat treatment on the processed commutator.

[0072] The commutator body 1 is provided with a commutator segment 2, a mica sheet 3, and an insulating bushing 4. The commutator segment 2 and the mica sheet 3 are arranged alternately. A clamping hoop A5 and a clamping hoop B6 are provided inside the clamping groove on one side of the commutator segment 2. The clamping hoop A5 and the clamping hoop B6 are installed in conjunction with the commutator segment 2 and the insulating bushing 4. The commutator segment 2 is L-shaped, and a clamping groove is provided on one side wall of the commutator segment 2. The outer wall of the insulating bushing 4 is provided with a clamping rib.

[0073] Arrange and combine the commutator segments 2, mica sheets 3, and insulating bushings 4 precisely according to the design requirements, and place the pre-assembled commutator segments 2, mica sheets 3, and insulating bushings 4 precisely on the positioning device of the mold. Use manual installation or automated robotic arm installation. After placement, confirm whether the inserts are fully in place and not loose, to ensure smooth injection molding in the later stage and ensure that the structure of the injection-molded commutator fully meets the standards.

[0074] The prepared commutator components are inserted and installed to form a "commutator segment assembly." This assembly is called the "insert" in injection molding.

[0075] The mold is closed and locked under high pressure to form a closed cavity, ready for injection molding. The clamping force must be large enough to resist the huge expansion force generated by the melt during injection molding.

[0076] The engineering plastic is pretreated and PBT (polybutylene terephthalate) is used as the engineering plastic. Before injection molding, the engineering plastic is fully dried in a dehumidifier at a drying temperature of about 120-150°C and a drying time of 4-6 hours. During the drying process, the dehumidifier continuously turns the engineering plastic to effectively avoid bubbles, silver streaks, and surface defects in the injection molded parts, which seriously affect the mechanical and electrical properties.

[0077] To accurately replicate the final shape of the commutator, including the plastic body and the space for accommodating the insert, the mold must have a high-precision and reliable positioning device to ensure that the commutator segment group will never move or deform during the mold closing and injection molding process. This is the key to ensuring the concentricity of the commutator, equal indexing between segments and final performance.

[0078] Design a reasonable position and number of gates (point gates, latent gates, fan gates, etc.) on the mold to ensure that the plastic melt can quickly, evenly and smoothly fill the entire cavity, avoid weld lines in key areas (such as hooks and between sheets), and reduce internal stress and orientation. It is crucial to set up an efficient and uniform cooling water channel design on the mold, which directly affects the production cycle and the dimensional stability and internal stress level of the product.

[0079] Effective exhaust grooves or exhaust needles are set at the end of melt filling and at locations where air is easily trapped to discharge the air in the cavity and the gas generated by plastic decomposition, preventing defects such as insufficient filling, burning, and bubbles.

[0080] Injection molding molds require the design of suitable ejector pins, push plates, and other mechanisms to ensure that the cured product can be ejected from the mold smoothly and without damage, avoiding damage to the insert or plastic surface.

[0081] PBT (polybutylene terephthalate) in a molten state is injected into the cavity at a pressure of 80-150 MPa. After the cavity is filled, the screw maintains a certain pressure (holding pressure, usually slightly lower than the injection pressure) and continues to slowly add material to the cavity.

[0082] In the mold cooling system, the melt gradually loses heat due to circulating cooling water / oil, transforming from a viscous flow state to a glassy or crystalline state. Cooling time accounts for 60-80% of the entire molding cycle. Sufficient cooling is key to ensuring product dimensional stability, sufficient strength for ejection, and minimizing deformation. Cooling must be uniform, otherwise it will lead to internal stress, warping, and other problems.

[0083] After cooling is completed, the mold is opened and the ejector mechanism is activated to smoothly push the solidified commutator product out of the mold cavity, remove the gate condensate and possible flash burrs on the product, and use manual deburring or mechanical borax treatment to deburr. After deburring, the commutator is placed in a hot water bath or steam humidity control treatment to remove the powder on the commutator surface and allow the commutator to reach a moisture balance state.

[0084] The commutator body 1 has a simple structure and adopts perfect one-piece injection molding, so that the completed commutator body 1 has good overall stability, the commutator has a good moisture absorption balance state, and the commutator has good balance performance.

[0085] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A processing technology for an integral injection-molded commutator, comprising the following steps: S1, preparing the commutator component materials, molding molds, and engineering plastic particles required for injection molding of the commutator body (1); S2. Install the prepared commutator components by inserting them and pre-treating the engineering plastics; S3. After the material is inserted and installed, the mold is closed and locked under high pressure to form a closed cavity. The clamping force must be large enough; S4. The dried plastic pellets are melted and mixed evenly in the barrel of the injection molding machine through the shear heat generated by heating and screw rotation, becoming a viscous melt; S5. In the molten state, the screw is driven forward at high speed by the cylinder, injecting the melt into the closed mold cavity at high pressure. The injection speed and pressure need to be precisely controlled to ensure that the cavity is filled quickly, smoothly and completely. S6: The melt gradually loses heat under the action of the mold cooling system (circulating cooling water / oil), changing from a viscous flow state to a solid state. The cooling time accounts for most of the entire molding cycle (about 60-80%). S7. After cooling is completed, the mold opens and the ejector mechanism operates to smoothly push the solidified commutator product out of the mold cavity. S8. Remove the gate solids and burrs on the finished commutator product, and perform heat treatment on the processed commutator.

2. The one-piece injection-molded commutator according to claim 1, characterized in that: The commutator body (1) is provided with a commutator segment (2), a mica sheet (3), and an insulating bushing (4); the commutator segment (2) and the mica sheet (3) are arranged alternately; a clamping hoop A (5) and a clamping hoop B (6) are provided inside a slot on one side of the commutator segment (2); the clamping hoop A (5) and the clamping hoop B (6) are installed in conjunction with the commutator segment (2) and the insulating bushing (4). The commutator segment (2) is L-shaped, and a clamping groove is provided on one side wall of the commutator segment (2). The outer wall of the insulating bushing (4) is provided with a clamping convex rib.

3. The one-piece injection-molded commutator according to claim 1, characterized in that: In step S2, the commutator segments (2), the mica sheets (3), and the insulating bushings (4) are precisely arranged and combined according to design requirements; Precisely placing the pre-assembled commutator segments (2), mica sheets (3), and insulating bushings (4) on the positioning device of the mold; Use manual installation or automated robotic arm installation. After placement, confirm whether the insert is fully in place and not loose.

4. The one-piece injection-molded commutator according to claim 1, characterized in that: In step S2, the engineering plastic is PBT (polybutylene terephthalate), and the engineering plastic is fully dried in a dehumidifier before injection molding. The drying temperature is about 120-150° C. and the drying time is 4-6 hours. During the drying process, the dehumidifier continuously turns the engineering plastic.

5. The one-piece injection-molded commutator according to claim 1, characterized in that: The mold must be equipped with a high-precision and reliable positioning device to ensure that the commutator segment group will not move or deform during the mold closing and injection molding process.

6. The one-piece injection-molded commutator according to claim 1, characterized in that: The molten PBT (polybutylene terephthalate) is injected into the cavity at a pressure of 80-150 MPa; After the cavity is filled, the screw maintains a certain pressure (holding pressure, usually slightly lower than the injection pressure) and continues to slowly add material into the cavity.

7. The one-piece injection-molded commutator according to claim 1, characterized in that: In step S8, manual deburring or mechanical borax treatment is used to remove the burrs. After the deburring is completed, the commutator is subjected to a hot water bath or steam humidity control treatment to remove powder on the commutator surface.

Images