JP6873804B2 - Insert molding method - Google Patents

Description

The present invention relates to an insert molding method.

Resin gears are used as an alternative to metal gears in many industrial fields, including OA equipment, due to their advantages such as weight reduction of parts, mass production by injection molding, non-lubricating operation during use, quietness and low vibration. Has been done.

Patent Document 1 discloses a method of coating a resin on the surface of metal gears (core material) by injection molding and a method of molding resin-coated metal gears.

However, according to the above-mentioned prior art document, the metal gear (core plate: insert metal spur gear) and the molding die are each heated to a predetermined temperature, and the molten resin is injection-molded to form the metal gear. It relates to a method of resin coating (insert molding) on the surface and a hybrid spur gear produced by the insert molding method.

In Examples 1 to 12 described in Table 1 of Patent Document 1, the temperature of the molding conditions is such that the molten resin temperature> the insert member temperature (insert metal spur gear temperature)> the mold temperature. The resin, insert metal, and mold are preheated.

Further, in Comparative Example 1 of Table 1, under the condition of the insert metal spur gear that has not been preheated at 20 ° C. <mold temperature of 80 ° C., resin cracking occurs after the molten resin is injected. That is, in the conventional insert molding method, after inserting the insert metal spur gear at room temperature into the mold adjusted to a predetermined temperature, the spur gear is heated to a temperature higher than the mold temperature. I couldn't.

Therefore, as is clear from Patent Document 1, in the conventional insert molding, an insert metal spur gear heated to a predetermined temperature higher than the mold temperature is loaded into the same mold at a predetermined temperature. Injection molding had to be done when the temperature of the metal spur gear dropped to a predetermined temperature.

That is, in this molding method, when the insert metal spur gear is preheated to a temperature higher than the mold temperature, inserted into the mold, and then naturally allowed to cool, the surface temperature of the spur gear reaches a predetermined temperature. So I had to do insert molding. Therefore, the conventional molding method has a problem that it takes a long time, the productivity is low, and it cannot be put into practical use.

If the insert metal spur gear can be heated to a predetermined temperature by rapid heating as a means for solving the problems of the conventional molding method, the time required for insert molding can be significantly shortened.

The resistance heating technology, which is the basis of the rapid heating method, has been applied to many products from the past. As an example of application to insert molding, for example, in Patent Document 2, in order to integrally mold a resin material on a metal member, for example, There is a control method in which the heating mechanism operates when the temperature sensor that detects the temperature of the metal member and the temperature detected by the temperature sensor are below the preset temperature, and the heating mechanism stops when the temperature exceeds the preset temperature. It is disclosed.

If the heating mechanism is not normally operated and stopped, rapid cooling or overheating will occur after the insert molding, and the insert molded product cannot be maintained at a constant temperature, resulting in quality deterioration.
That is, the technique described in Patent Document 2 does not hold the mold at a constant temperature, but merely integrates the metal member and the resin material. Therefore, the integration includes a sensor for measuring the temperature of the metal member. I had no choice but to control the temperature of the metal members by utilizing the above. Therefore, the technique described in Patent Document 2 has a problem that it does not have a mechanism for keeping the resin coated on the hybrid spur gear at a constant temperature (heat treatment) after insert molding.

Patent No. 443509 Patent No. 5928949

Therefore, the invention of this application solves the conventional problems from the above background, and inserts the insert metal spur gear below the mold temperature in the mold without preheating the insert metal gear to a predetermined temperature. By a method of rapidly heating the same metal spur gear after insertion into, a method of automating the insert molding process, and an insert molding hybrid spur gear heat retention mechanism in a mold held at a predetermined temperature after insert molding, a hybrid is used. It is an object of the present invention to provide a technical means for dramatically increasing the productivity of spur gears and a hybrid spur gear having strength, abrasion resistance and durability exceeding the usage limit of the same type of resin spur gear.

The invention of this application solves the above-mentioned problems. First, an insert metal spur gear having a temperature lower than the mold temperature is inserted and mounted at a predetermined position in a mold set to a predetermined temperature. After placement, the surface of the insert metal spur gear is heated by the rapid heating mechanism, and heating is stopped when the surface temperature near the teeth of the insert metal spur gear reaches a predetermined temperature equal to or higher than the mold temperature and lower than the molten resin temperature. At the same time, an insert molding method is provided, which comprises injection molding or extrusion molding of a molten resin in the mold and coating the surface of the insert metal spur gear with the resin to form a hybrid spur gear.

Second, a mechanism for recognizing the position of the insert metal spur gear, a mechanism for grasping the spur gear and inserting and placing it at a predetermined position in the mold, and a hybrid spur gear after insert molding are inserted from inside the mold. Provided is the above-mentioned first hybrid spur gear insert molding method, which comprises molding a hybrid spur gear by an automated technical means having a taking-out mechanism.

Thirdly, any of the above-mentioned insert forming methods, characterized in that the surface of the insert metal spur gear is heated for a predetermined time by a rapid heating mechanism that enables energization heating through the mold, and then the energization heating is stopped. I will provide a.

Fourth, any of the above-mentioned insert molding methods is provided, which comprises inserting and placing an insert metal spur gear in a room temperature state in a mold.

Fifth, a spur gear having a resin coated on the surface of the metal spur gear within a range of 0.1 mm or more and 5 mm or less by the insert molding method described in the previous section, which is the same type of resin spur gear. Provided is a method for manufacturing a hybrid spur gear by insert molding, which comprises manufacturing a hybrid spur gear having strength, abrasion resistance and durability exceeding the usage limit of the above.

Further, the invention of this application states that the surface of a metal spur gear is coated with a resin within a thickness range of 0.1 mm or more and 5 mm or less, and has at least the following characteristics (A), (B) and (C). Provided is a featured insert-molded hybrid spur gear.

(A) Strength: It can withstand a load condition in which the K value, which is an index showing the strength of the gear, is 1 MPa or more. (However: the rotation speed is 1,000 rpm, and the mating gear is carbon steel for machine structure S45C).

(B) Wear resistance: Even if the total number of revolutions reaches 10 million under the load condition of (A), the wear does not progress excessively, and there is a large change in the variation in torque transmission and rotation angle transmission at the initial stage of operation. Has the ability not to occur.

(C) Durability: Under the load condition of (A), it has the ability to maintain the vibration and noise level of the machine within the range that can withstand practical use even if it achieves 10 million times.

According to the invention of this application, it is not necessary to preheat the insert metal spur gear above the mold temperature before inserting and placing it in the mold by using the automation of a series of molding processes in combination, and the mold. A new hybrid spur gear mass production technology is provided, which realizes a significant reduction in manufacturing time by rapidly heating the insert metal spur gear after being inserted and placed inside and immediately performing insert molding.

Further, since the hybrid spur gear according to the technique of the invention of the present application has a structure in which the tooth surface and the tooth side surface excluding the central portion of the metal spur gear are covered with resin, the tooth surface and the resin have high adhesion. The resin layer does not break or peel off, and the resin layer is formed on the surface of the metal spur gear, which imparts self-lubricating property, noise reduction, and vibration reduction of the resin to the metal spur gear. The surface resin layer is given the high strength and high rigidity of the internal metal spur gear, and due to the synergistic effect of the advantages of metal and resin, it is a highly durable spur gear with high power transmission performance under high torque. It has utility value in a wide range of industrial fields such as OA equipment field, transportation equipment field, medical equipment field, food manufacturing machine field, and various robot fields. Furthermore, the insert molding method of this application can be applied not only to hybrid spur gears but also to hybrid bevel gear fabrication.

It is the schematic of the mold for insert molding provided with the rapid heating mechanism.

The invention of this application has the characteristics as described above, and the embodiments thereof will be described in detail below.

In the insert molding method of the invention of the present application, as described above, an insert metal spur gear having a temperature lower than the mold temperature is inserted into a predetermined position in a mold set to a predetermined temperature, and after mounting, a rapid heating mechanism is provided. Heats the surface of the insert metal spur gear, and stops heating when the surface temperature of the insert metal spur gear reaches a predetermined temperature equal to or higher than the mold temperature and lower than the molten resin temperature, and at the same time, melts in the mold. It is characterized in that a resin is injection-molded or extruded, and the surface of the insert metal spur gear is coated with the resin to form a hybrid spur gear.

The "rapid heating mechanism" here may be of various types, and as will be described later, a mechanism capable of energizing and heating through a mold is exemplified as a preferred form thereof. And, "rapid heating" here is generally considered as the rate of temperature rise of 30 ° C./sec or more.

Resin-coated insert metal spur gears are used in various fields such as OA equipment parts, transportation equipment parts, medical equipment parts, and food manufacturing machines, and are spur gears that are responsible for power transmission and rotation angle transmission. , Dimensions, shape and the like are not particularly limited, and further, the dimensions and shape are not particularly limited as long as they are mating gears having a tooth structure that appropriately meshes with the insert metal spur gear.

The type and composition of the material of such an insert metal spur gear are not particularly limited, but for example, at least one selected from steel, iron, copper, aluminum, titanium or an alloy containing them, or a composite member thereof. A solid containing the above is exemplified as a suitable object, and the method for producing the insert metal spur gear is not particularly limited.

Further, the surface of the insert metal spur gear is processed in advance by etching with chemicals or the like, silane coupling treatment, adhesive coating of phenol-based resin or epoxy-based resin, plasma surface treatment in the presence of ammonia or hydrazine, or the like. Alternatively, it may be modified, the surface treatment method is not particularly limited, and the surface treatment may not be performed.

Then, in the production of the hybrid spur gear by the insert molding of the invention of the present application, the temperature of the insert metal spur gear before being inserted into the mold is eliminated in order to eliminate the loss of production time due to the preheating of the insert metal spur gear. Is preferably equal to or lower than the mold temperature, and more preferably, it is at room temperature without preheating.

The molding machine is preferably a vertical molding machine, more preferably a vertical rotary molding machine provided with a rotary table, and examples thereof include one or two lower dies on the rotary table. In this case, the time required to manufacture the hybrid spur gear is shortened when the number of lower molds is two.

The insert metal spur gear is inserted and placed in a lower mold fixed on a rotary table of a vertical rotary forming machine. The means for inserting and mounting the insert metal spur gear into the mold is not particularly limited, but a mechanism for recognizing the position of the insert metal spur gear, the spur gear is gripped and placed at a specified position in the mold. It is preferable to adopt an automation technique using a multi-axis robot with a mechanism for inserting and placing.

In the case of a rotary table with two lower dies, when the insert metal spur gear is placed on the lower die, the rotary table automatically rotates 180 degrees and then stops and is set to a predetermined temperature. Fits with the mold.

At the same time that both molds are fitted, for example, as shown in the schematic cross-sectional view of the rapid heating mold of FIG. 1, the external power source 7 is used to both the upper mold 2 and the lower mold 3 of the rapid heating mold 1. When it comes into contact with one end of the electrode 8 protruding from each side surface of the mold, the other end having a heat generating mechanism arranged inside each of the upper mold 2 and the lower mold 3 coated with the heat insulating material 10. When the heater 9 comes into contact with the surface of the insert metal spur gear 4 near the shaft, electricity is applied to rapidly heat the surface of the insert metal spur gear 4.

The heat generating mechanism is not limited to the structure illustrated in FIG. 1 as long as the surface of the insert metal spur gear can be rapidly heated.

For example, in the above-mentioned energization, the energization time (not shown) incorporated in the rapid heating mold 1, that is, the heating time of the insert metal spur gear 4, is obtained in advance by obtaining the relationship between the energization time and the temperature near the teeth. If it is set, the temperature of the target tooth portion can be determined by the energization time. The energizing time is set according to the dimensions, weight, shape, amount of resin, type of gear and resin material, etc. of the gear. It is preferable that the surface temperature of the gear is equal to or higher than the mold temperature and lower than the temperature of the molten resin.

After the surface near the teeth of the insert metal spur gear reaches a predetermined temperature by the rapid heating, the energization can be stopped or continued as needed. When the energization is continued, the surface temperature near the teeth of the insert metal spur gear can be changed. The molten resin automatically held at a predetermined temperature is inserted from the gate of the upper mold 2 through the spool runner 5 into the cavity 6 on the gear surface in the peripheral portion including the teeth, excluding the vicinity of the shaft of the insert metal spur gear 4. It is molded. As shown in FIG. 1, if the plate thickness near the shafts on both sides of the insert metal spur gear is thicker than the peripheral portion including the teeth, only the surface near the shafts of the insert metal spur gear is the upper mold 2 and It adheres to the surface of the lower mold 3 and the molten resin does not reach the surface near the shaft of the gear. The shape of the insert metal spur gear 4 is not particularly limited as long as the structure does not allow the molten resin to enter the position of the electrode (heater) 9 in contact with the surface of the insert metal spur gear 4 near the shaft.

Therefore, after insert molding, the resin is filled in the cavity 6 to form a shape that wraps the entire peripheral portion including the vicinity of the teeth of the insert metal spur gear 4. The shape, size, and the like of the cavity 6 and the corresponding resin wrapping are appropriately set in consideration of the application, performance, and the like of the insert metal spur gear. The peeling strength of the resin layer on the tooth surface is not only the adhesive strength between the surface of the insert metal spur gear 4 and the resin, but also the anchor effect as a shearing force applied to the resin layer on the metal surface, and further, the resin layer. The wrapping effect complementarily contributes to the durability of the hybrid spur gear.

For engineering resins having a high melting point, resins having a high melt viscosity, or resins that need to be insert-molded at as low a temperature as possible, it is preferable to form hybrid spur gears by extrusion molding or the like.

The resin used for insert molding of the invention of the present application is not particularly limited as long as it is a polymer substance that can be injection-molded or extrusion-molded, and is a crystalline polymer, an amorphous polymer, a homopolymer, or a coweight. Coalescence, polymer blends, polymer alloys are exemplified. Among them, crystalline polymers such as ultra-high molecular weight polyethylene, polyacetal, polyamide, polybutylene terephthalate, polyphenylene sulfide, polyphenylene ether, liquid crystal polymer, polyether ether ketone, polytetrafluoroethylene, and these crystalline polymers and carbon fibers, Composite materials such as glass fibers, single-layer carbon nanotubes, cellulose nanofibers, and inorganic fibers are exemplified as suitable materials.

The thickness of the resin layer coated on the surface of the metal spur gear by insert molding is set in consideration of, for example, the peel strength and the characteristics of the resin from the viewpoint of the intended use and performance of the hybrid spur gear. It's okay. In general, the insert metal spur gear needs to have sufficient strength and rigidity in order to prevent fracture and suppress deformation against a load applied in the tangential direction of the tooth surface of the hybrid spur gear. On the other hand, the coating resin needs to have a certain thickness in order to exhibit vibration damping and noise reduction due to the viscoelastic effect, and the thickness of the resin layer is preferably in the range of 0.1 to 5 mm. It is more preferably in the range of 0.2 to 2 mm, still more preferably in the range of 0.3 to 1 mm.

A hybrid spur gear having such a resin thickness has remarkable features as having strength, wear resistance, and durability exceeding the usage limits of conventional resin spur gears of the same type.

Here, an example of typical performance is as follows.
(A) Strength: It can withstand a load condition in which the K value, which is an index showing the strength of the gear, is 1 MPa or more. (However: the rotation speed is 1,000 rpm, and the mating gear is carbon steel for machine structure S45C).

(B) Wear resistance: Even if the total number of revolutions reaches 10 million under the load condition of (A), the wear does not progress excessively, and there is a large change in the variation in torque transmission and rotation angle transmission at the initial stage of operation. Has the ability not to occur. (C) Durability: Under the load condition of (A), it has the ability to maintain the vibration and noise level of the machine within the range that can withstand practical use even if it achieves 10 million times.

After insert molding, for example, in the example of FIG. 1, the lower mold 3 returns to its original position by rotating the rotary table 180 degrees, and at the same time, the robot automatically inserts the hybrid spur gear produced from the lower mold 3 into the lower mold 3. Grasp and store in the storage device.

Therefore, an example will be shown below, which will be described in more detail. Of course, the invention is not limited by the following examples.

<Example 1>
An insert metal spur gear having a module of 0.8, a reference circle diameter of 20 mm, a number of teeth of 25, and a tooth width of 11.2 mm was produced by gear cutting a round bar steel made of S45C. A resin having a thickness of 0.3 mm was prepared on the surface of the same metal spur gear so that the tooth profile after insert molding had parallel teeth. At room temperature of 25 ° C, the insert metal spur gear placed in the specified position is grasped by a 6-axis robot and placed in the specified position on the rotary table of the vertical rotary molding machine, and the temperature reaches 80 ° C. It was automatically and accurately inserted and placed in one of the held lower molds. Under a series of automatic operations, the rotating table is swiftly rotated 180 degrees, and after stopping at the specified position of the molding machine, the upper mold held at a temperature of 80 ° C drops and fits into the lower mold. At the same time, the electrodes of both molds were energized for 4.0 seconds by an external power source to perform rapid heating. The surface temperature of the insert metal spur gear when the energization was stopped was 165 ° C. Although rapid heating was performed at a heating rate of 40 ° C./sec, it took 0.5 seconds for the initial temperature rise of the surface of the insert metal spur gear.
Immediately after the energization is stopped, a polyacetal resin (POM: Delrin 100P manufactured by Polyplastics Co., Ltd.) in a molten state at 230 ° C. is insert-molded through multiple gates, held in the mold for 30 seconds, and then the mold is opened. , The lower mold returned to its original position by rotation. Subsequently, the molded hybrid spur gear was placed in the heat insulating device by the automatic operation of the 6-axis robot, and the molding was completed.

Not only immediately after molding, but also the resin layer on the surface of the hybrid gear stored at room temperature for one month after molding did not crack or break. In addition, as a result of three-dimensional shape measurement, it became clear that the hybrid spur gear was formed as designed. As a result, the metal insert spur gear at room temperature, which is lower than the mold temperature, is inserted into the mold, placed, and then rapidly heated, so that the surface temperature of the metal spur gear is higher than the mold temperature (80 ° C.). It was proved that insert molding is possible when the temperature reaches 165 ° C., which is lower than the molten resin temperature (230 ° C.) (energization time: 4.0 seconds).

It took about 60 seconds from gripping the insert metal spur gear at room temperature with the robot until the insert molding was completed and the hybrid spur teeth were taken out. It was proved that this molding time was reduced to about 1/60 of the manual molding time shown in Comparative Example 1.

<Example 2>
Insert molding was performed under the same conditions as in Example 1 except that an insert metal spur gear produced by gear cutting a sintered metal round bar was used. As a result, the time from gripping the insert metal spur gear at room temperature with the robot to the completion of insert molding and taking out the hybrid spur gear was about 60 seconds, and the obtained hybrid spur gear was obtained in Example 1. Similarly, there were no cracks or cracks in the surface resin layer, and the three-dimensional shape was as designed.
<Example 3>
For the purpose of mass production of hybrid spur gears, a mold for producing a sintered insert metal spur gear having the same size as that of Example 2 as a core plate was produced, and the sintered insert metal spur gear was produced using this mold. 50 pieces were prepared. It was confirmed by three-dimensional shape measurement that the obtained sintered insert metal spur gear was a product as designed. Insert molding was performed in the same manner as in Example 2 using five of these sintered insert metal spur gears. The five insert moldings were carried out by continuous production by a robot, and the production time per one was about 60 seconds as in Examples 1 and 2.

As a result, as in Examples 1 and 2, all the obtained hybrid spur gears had no cracks or cracks in the surface resin layer, and the three-dimensional shape was as designed.
<Example 4>
This was carried out except that three of the 50 sintered insert metal spur gears produced in Example 3 were used and the surface temperature of the metal spur gear was set to 170 ° C. (energization time 4.1 seconds) by rapid heating. Insert molding was carried out under the same conditions as in Examples 1 to 3. As a result, the molding time per piece was about 65 seconds, but as in Examples 1 to 3, no resin cracking occurred, insert molding could be performed without any problem, and the shape of the molded hybrid spur gear was Everything was made as designed.
<Example 5>
Insert molding was carried out in the same manner as in Example 4 except that the surface temperature of the sintered insert metal spur gear was set to 160 ° C. (energization time 3.9 seconds), and a molded hybrid spur gear could be manufactured as designed.
<Example 6>
Using polyphenylene sulfide resin (PPS), the mold temperature was set to 150 ° C. and the molten resin temperature was set to 310 ° C., and 5 of the sintered insert metal spur gears produced in Example 3 reached a surface temperature of 200 ° C. by rapid heating. At that time (4.9 seconds), insert molding was performed, the mold was held for 50 seconds, and insert molding (about 75 seconds per piece) was performed by continuous production by a robot in the same manner as in Example 3. No cracks or cracks occurred in the surface resin layer of the obtained hybrid spur gear, and the hybrid spur gear could be manufactured as designed.
<Example 7>
Using the hybrid spur gear (tooth surface resin: POM) produced in Example 3 as the drive gear and the geared sintered spur gear as the driven gear, a prototype power transmission tester consisting of various commercially available high-performance measuring instruments was used. The test was carried out at room temperature, under oilless (non-lubricated), torque 1.65 Nm (tangential force on the reference circle: 165 N), and rotation speed 1,000 rpm. Vibration measurements during the test were performed and compared to measurements of POM resin spur gear pairs under oil lubrication. As a result, it was clarified that the hybrid spur gear / sintered spur gear pair reduced the vibration by 4 to 16 dB as compared with the resin spur gear pair made of POM.

Further, it was obtained that the hybrid spur gear pair under oil lubrication had a rotation angular velocity accuracy reduced by 5 to 65% due to the variation in angular velocity as compared with the sintered spur gear / sintered spur gear pair under oil lubrication.

Further, under oilless conditions, with a torque of 1.65 Nm and a rotation speed of 1,000 rpm, the hybrid flat drawing wheel (surface resin: POM) produced in Example 3 is used as the drive side, and the carbon steel material S45C for machine structure is used as the driven side. ,
Under the same conditions, a durability test was carried out up to a total rotation speed of 1 million times, and the surface shape was measured. As a result, in the case of POM resin spur gears, the gears were destroyed when the total number of rotations was about 500,000, but even if the total number of rotations exceeded twice that, the tooth profile after the test was the same as before the test. It was also revealed that the hybrid spur gear of the present invention has high wear resistance with almost no change.

As a result of conducting a power transmission test of the hybrid spur gear in order to examine the durability of the hybrid spur gear in addition to the wear resistance, the total number of rotations, which is an index of the durability of the metal gear, is 10 million. It was revealed that it has durability over times.
The K value at this time is calculated as follows and shows 1.47 MPa.

K = P / db × (i + 1) / i
Here, P (tangential force on the reference circle): 165N
d (reference circle diameter): 20 mm
b (tooth width): 11.2 mm
i (gear ratio): 1
<Example 8>
Oilless as in Example 7 except that the hybrid spur gear (tooth surface resin: PPS) produced in Example 6 was used as a drive gear, the carbon steel material S45C for machine structure was used as a driven gear, and the test temperature was set to 150 ° C. A power transmission test was conducted under (no lubrication) at a torque of 1.65 Nm and a rotation speed of 1,000 rpm.

Moreover, it was compared with the measurement of the resin spur gear pair made of PPS under oilless. As a result, in the case of PPS resin spur gears, the gears were destroyed when the total number of rotations was about 400,000, but even if the total number of rotations exceeded three times that number, the tooth profile after the test was the same as before the test. With almost no change, it was revealed that the hybrid spur gear of the present invention has high abrasion resistance.

As a result of conducting a power transmission test of the hybrid spur gear in order to examine the durability of the hybrid spur gear in addition to the wear resistance, the total number of rotations, which is an index of the durability of the metal gear, is 10 million. It was revealed that it has durability over times.
<Example 9>
Using polyetheretherketone resin (PEEK), the mold temperature was set to 160 ° C and the molten resin temperature was set to 430 ° C, and three of the sintered insert metal spur gears produced in Example 3 were rapidly heated to a surface temperature of 250 ° C. When the temperature reached (6.1 seconds), insert molding was performed, the mold was held for 50 seconds, and insert molding (about 90 seconds per piece) was performed by continuous production by a robot in the same manner as in Example 3. No cracks or cracks occurred in the surface resin layer of the obtained hybrid spur gear, and the hybrid spur gear could be manufactured as designed.
<Comparative example 1>
The metal reached 200 ° C after preheating the sintered insert metal spur gear at room temperature in a preheating furnace at 300 ° C for about 10 minutes by hand instead of continuous production by the rapid heating method and robot using a horizontal forming machine. The spur gear was inserted into a fixed mold at 110 ° C, and after mounting, it was confirmed that the surface temperature of the metal spur gear had dropped to 150 ° C, the mold was closed, and the POM molten resin at 230 ° C was used. Was insert-molded. After holding in the mold for 1 minute, the mold was opened and the hybrid spur gear was taken out.

The time from manually placing the insert metal spur gear at room temperature into the preheating furnace to the completion of insert molding using a horizontal molding machine was about 60 minutes.

This result shows that the molding time by hand required 60 times as long as the molding time by the rapid heating method using the robot of Example 1, demonstrating that the invention of this application is an excellent technique. doing.
<Comparative example 2>
The metal reached 290 ° C after preheating the sintered insert metal spur gear at room temperature in a preheating furnace at 400 ° C for about 10 minutes by hand instead of continuous production by the rapid heating method and robot using a horizontal forming machine. The spur gear was inserted into a fixed mold at 150 ° C, and after mounting, it was confirmed that the surface temperature of the metal spur gear had dropped to 200 ° C, the mold was closed, and the PPS molten resin at 310 ° C was used. Was insert-molded. After holding in the mold for 1 minute, the mold was opened and the hybrid spur gear was taken out.

It took about 30 minutes to manually put the insert metal spur gear at room temperature into the preheating furnace, and then slowly cool it to room temperature through insert molding using a horizontal molding machine.

This result shows that the molding time by hand required 26 times as long as the molding time by the rapid heating method using the robot of Example 6, proving that the invention of this application is an excellent technique. doing.
<Comparative example 3>
Examples 1 to 3 except that three of the 50 sintered insert metal spur gears produced in Example 3 were used, and the surface temperature of the metal spur gear was left at room temperature without rapid heating. Under the same conditions, insert molding of POM was carried out. As a result, in each case, the resin was not coated on the entire tooth tip, and only the defective product, so-called short, which was coated only on the portion near the gate, was obtained.
<Comparative example 4>
In order to investigate the insert moldability of the metal spur gear under the same conditions as in Patent Document 2, insert molding is performed under the same conditions as in Example 1 except that the lower die is kept at room temperature (25 ° C.) without preheating. The test was conducted. Since the lower mold is at room temperature, the coating resin after molding is rapidly cooled, and as a result, the same resin as in Comparative Example 3 is not coated on the entire tooth portion. Cracks and breaks occurred, and only defective products were obtained. That is, it was clarified that the resin layer having a thickness of 0.3 mm cannot be insert-molded under the same molding conditions as in Patent Document 2.
<Comparative example 5>
Using polyphenylene sulfide resin (PPS), the mold temperature was set to 150 ° C. and the molten resin temperature was set to 310 ° C., and two of the sintered insert metal spur gears produced in Example 3 were not rapidly heated and remained at room temperature. Insert molding was performed in the mold for 50 seconds, and insert molding (about 75 seconds per piece) was performed by continuous production by a robot in the same manner as in Example 3. As a result, on the surface of the hybrid spur gears obtained in each case, only a defective product called a short, in which the resin was coated only on the portion near the gate, was obtained.
<Comparative Example 6>
Using polyetheretherketone resin (PEEK), the mold temperature was set to 160 ° C and the molten resin temperature was set to 430 ° C, and three of the sintered insert metal spur gears produced in Example 3 were used without rapid heating. The temperature of the metal spur gear was insert-molded at room temperature and held in the mold for 50 seconds. As a result, on the surface of the hybrid spur gears obtained in each case, only a defective product called a short, in which the resin was coated only on the portion near the gate, was obtained.

1 Rapid heating mold 2 Upper mold 3 Lower mold 4 Insert metal spur gear 5 Molten resin spool runner 6 Cavity 7 Power supply 8 Electrode 9 Heater 10 Insulation material

Claims (2)

An insert metal spur gear having a temperature lower than the mold temperature is inserted and placed at a predetermined position in a mold set to a predetermined temperature, and then the surface of the insert metal spur gear is heated by a rapid heating mechanism to heat the insert metal. When the surface temperature of the tooth part of the spur gear reaches a predetermined temperature equal to or higher than the mold temperature and lower than the molten resin temperature, heating is stopped, and at the same time, the molten resin is injection-molded or extruded into the same mold. Insert This is an insert molding method in which the surface of a metal spur gear is coated with resin to form a hybrid spur gear.
A mechanism for recognizing the position of the insert metal spur gear, a mechanism for grasping the insert metal spur gear and inserting and placing it in a specified position in the mold, and a rapid heating mechanism for heating the insert metal spur gear to a specified temperature. The molten resin is injection-molded or extrusion-molded in the mold, and the molten resin is coated on the surface of the insert metal spur gear with a thickness within the range of 0.1 mm or more and 5 mm or less to be a hybrid spur gear. The hybrid spur gear is molded by an automated technical means having a mechanism for insert molding, a mechanism for taking out the hybrid spur gear after insert molding from the mold and placing it in a heat insulating device, and a mechanism for keeping the hybrid spur gear warm in the heat insulating device. An insert molding method characterized by The insert molding method according to claim 1, wherein an insert metal spur gear in a room temperature state is inserted and placed in a mold.

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