JP3053792B2 - Thermal welding equipment for thermoplastic resin molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin molded article used for fixing a lens to a resin molded article member .
The present invention relates to a heat welding device.

[0002]

2. Description of the Related Art As one method of fixing an object to be fixed to a plastic base formed of a thermoplastic resin, a fixing rib is provided on a plastic base side, and the fixing rib is thermally deformed to fix the object to be fixed. There is a method of fixing while pressing. As a specific example, a ring-shaped heating element based on electric resistance (hereinafter referred to as a “resistance heating element”) is used as a means for fixing a lens to a molded article member formed of a thermoplastic resin.
) Is pressed against the fixing ribs provided around the lens, and a voltage is applied to the resistance heating element to instantaneously generate heat to soften the fixing ribs, and further press the resistance heating element to the lens side. The applicant of the present application has filed a Japanese Patent Application No. 8-345284 in which a lens is fixed to a molded product member by instantaneously cooling and fixing and fixing the fixing rib. This method can be cooled and hardened while the resistance heating element is pressed against the fixing rib, so that it is a reliable fixing method without lifting or rattling of the lens to be fixed.

[0003] One method of joining members formed of thermoplastic resin to each other is a heat welding method in which a resistance heating element is sandwiched between members formed of thermoplastic resin.
As a specific example, a ring-shaped resistance heating element is sandwiched between joining surfaces of a case body and a cover molded of a thermoplastic resin, and a voltage is applied through a through-hole formed in the case body in advance so as to reach the resistance heating element. After the application terminal is brought into contact with the resistance heating element, a voltage is applied to the resistance heating element from the voltage application terminal to melt the bonding surface due to the instantaneous heat generation, and then the case body and the cover are hardened by cooling. The applicant of the present invention has applied for a welding method as Japanese Patent Application No. 8-209647. This method is characterized in that the built-in electronic components are not affected by vibrations such as ultrasonic welding and that the time required for bonding is not required unlike an adhesive.

In each of the fixing method and the heat welding method described in the above example, a portion where the line length of the resistance heating element is approximately equal to two is used as a voltage application electrode. When a voltage is applied to one electrode, the current is divided into two and flows to the other electrode,
It is known that the heat generated by the resistance is generated from an intermediate point between the electrodes, and then proceeds toward each electrode.

When the length between the electrodes is short, the time lag of heat (time lag) can be neglected, but the time lag may not be negligible due to the length between the electrodes and the shape of the resistance heating element. For example, even though the resin has reached the softening temperature near the center between the electrodes, the vicinity of the electrodes has not yet reached the softening temperature and is not welded, or conversely, when the temperature near the electrodes has reached the softening temperature, the vicinity of the center is exposed to high temperatures for a long time. As a result, heat causes a reduction in the molecular weight of the resin and abnormal deformation of the molded product. Like this
There is a case where it is very difficult to control the heat generation in which the heat generation temperature is uniformly generated depending on the shape of the resistance heating element.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic resin in which a heating temperature distribution of a resistance heating element is uniformly generated in the resistance heating element and a thermoplastic resin can be softened or melted by uniform heat.
An object of the present invention is to provide a heat welding apparatus for resin molded products .

[0007]

In order to solve the above-mentioned problems, the following means are effective. The plastic base fixing rib which is molded by a thermoplastic resin is thermally deformed les
Used to secure the lens to the plastic base.
In that the welding device, a resistive heating element the ribs thermally deformed to form a ring shape, the line length of the ring-shaped and receiving section a portion of an even number equal, different pole power receiving unit to further adjacent in the power receiving unit and then, the voltage and mark pressurized by heating the resistance heating element by passing a current to between the two poles which summarizes the same poles that are set as the fixed rib is pressed against it in the fixing rib the fixing rib with a lens by thermal deformation toward the lens to adopt a multi-pole voltage application method wherein the plastics base f fixed is thermally deformed
After that, the cooling air is blown onto this for cooling.
Welding equipment for thermoplastic resin molded products with attached IPs.

[0008]

[Function] When a voltage is applied to a ring-shaped resistance heating element,
Although the voltage was applied to the two portions where the wire length is approximately equally divided into two portions as the power receiving portion, the heat welding apparatus of the present invention defines the portion where the wire length is evenly divided as the power receiving portion and defines as described above. Among the received power receiving units, the adjacent power receiving units are used as different poles and are unified into two poles. In addition, a uniform heating temperature distribution of the resistance heating element can be made uniform by applying an AC voltage between the two unified poles. As a result, abnormal deformation of the molded product due to local overheating and fixed strength due to insufficient heating are achieved. This makes it possible to easily set the heat generation conditions of the resistance heating element without fixed welding variation such as insufficient welding strength and insufficient welding strength. By using an alternating current as the voltage applied to the resistance heating element, an appropriate voltage can be easily obtained without rectification like a direct current, and the heat generation efficiency is further improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In a plurality of power receiving units provided on a resistance heating element, power receiving units other than adjacent power receiving units are connected to each other, and a plurality of power receiving units are connected to a secondary side of a wound transformer for obtaining a desired voltage. Connect each. The primary side is connected to an AC power supply, and a connection is made between the primary side of the transformer and the AC power supply via a relay that opens and closes power supply to the transformer primary side.
The control circuit for controlling the opening and closing of the relay may be any circuit that can control the instantaneous opening and closing time of the relay.
An embodiment of the present invention will be described with reference to the drawings.

[0010]

[Embodiment 1] In this embodiment, an embodiment in which the line length of a ring-shaped resistance heating element is divided into four equal parts will be described. First, the device of the present invention
For fixing a lens to a thermoplastic resin molded article
It will be described. Specifically, this is an example of fixing a lens by thermally deforming a fixing rib integrally formed on a part of a camera housing formed of a thermoplastic resin.

FIGS. 1, 2, 3 and 4 relate to the apparatus of the present invention.
That is a schematic view of a heater unit 100. FIG. 1 is an exploded perspective view of a main part of the heater unit 100, FIG. 2 is a sectional view taken along the line AA ′ of the resistance heating element 110 in FIG. 1, and FIG. Is a completed view of the heater unit 100 in which the resistance heating element 110 and the mounting plate 20 are further fixed by the cover 140. FIG. 5 is a plan view of the heater unit 100 viewed from the contact surface 111 of the resistance heating element 110, FIG. 6 is a sectional view taken along the line BB ', and FIG. 7 is a sectional view taken along the line CC'.

The resistance heating element 110 of the heater unit 100 used in the present invention is made of metal of die steel (SKD), has an average thickness of 0.6 mm, and has a contact surface 111 having a circular shape with a diameter of 60 mm. ing. As shown in FIG. 2, the circumference of the contact surface 111 of the resistance heating element 110 has a lens to be fixed and a side wall 112 for butt guide, and further has a curvature of the surface of the lens 200 to be fixed. The same inclined surface 113 is formed.

At the other end remote from the contact surface 111, a folded portion 114 is provided on the entire periphery of the end so as to protrude toward the center so that the strength against external pressure is improved. Connection terminals (power receiving units) 115, 116, and 11 for electric wire connection are provided at portions that divide the circumference of 111 into approximately four equal parts.
Four of 7, 118 are formed with an appropriate length in the axial direction of the resistance heating element 110.

As is apparent from FIG. 1, the shape of the mounting plate 120 is two of a column A121 and a column B122 having different diameters.
It is composed of steps. In the cylinder A121 having a smaller diameter, an insertion hole 124 serving to fix the pipe 123 in a predetermined positional relationship with respect to the resistance heating element 110 is formed in the center thereof through the cylinder A121 and the cylinder B122 in the axial direction. Further, the outer circumference of the column A121 is connected to the connection terminals 115, 1
In order to eliminate the influence of the external pressure applied to the connection terminals 16, 117, and 118, the connection terminals 115, 116, 117, and 118 are configured to be in contact with and support the inner surfaces thereof.

A cylinder B12 having a diameter larger than that of the cylinder A121.
2 is provided with four ventilation holes 125 in the axial direction for allowing the cooling medium blown into the resistance heating element 110 from the pipe 123 to escape to the outside, and through each connection terminal provided in the resistance heating element 110. Through holes 126 are formed in the axial direction at four locations. FIG. 3 shows that after connecting each connection terminal of the resistance heating element 110 through the through hole 126 of the mounting plate 120, the connection terminal 115 has the electric wire 130, the connection terminal 116 has the electric wire 131, the connection terminal 117 has the electric wire 132, and the connection terminal 11 has the electric wire 132.
8 is a diagram in which electric wires 133 are electrically connected to each other by welding or the like.

Thereafter, the resistance heating element 110 and the mounting plate 120
Are adhered to each other, and the cover 140 is formed using a heat-resistant synthetic resin. As a result, both the resistance heating element 110 and the mounting plate 120 are fixed, and the exposed portions of the electric wires can be covered and fixed. Note that a semicircular groove 141 is provided in a portion of the cover 140 that is in contact with the ventilation hole 125 to improve exhaustability. The heater unit 100 used in the first embodiment shown in FIG. 4 is completed after the above steps are completed.

Next, each electric wire connected to each connection terminal is
Each electric wire is connected to each other by using a relay terminal or another connection member so that the other connection terminals except the adjacent connection terminal have the same polarity. In FIG. 4, the electric wire 130 and the electric wire 132 are connected to form the same polarity A pole, and the electric wire 131 and the electric wire 133 are connected to form the same polarity B pole. Although the connection is made outside the cover 140 in the first embodiment, the connection may be made inside the cover 140.

FIG. 5 is a plan view of the heater unit 100 as viewed from the contact surface 111 of the resistance heating element 110. There is a pipe opening hole 127 at the center, and four ventilation holes 125 are drilled around it. The connection between the heater unit 110 and the power supply (not shown) is such that the A pole and the B pole have a capacity of 45.
It is connected to the secondary side of a 0 VA winding transformer, and the primary side of the winding transformer is connected to 200 VAC through a relay.

The secondary side of the winding transformer used in the first embodiment is designed so that 12 V AC can be obtained at a rated load. A pipe 123 protruding from the cover 140 is connected to a solenoid valve (not shown) via an air hose. The opening / closing control of the solenoid valve is performed by a control circuit which controls the relay.

Next, the operation of the first embodiment will be described with reference to FIGS.
A description will be given based on FIG. In addition, the control circuit for controlling the relay and the solenoid valve is provided with a start time → [1
Next energization (heating) 2 seconds] → [Electrification stop (remaining heat) 0.5
Second] → [secondary energization (heating) 1.5 seconds] → [energization stop (remaining heat) 5 seconds] → [solenoid valve open (forced cooling) 2
Seconds] → end was set.

The camera housing for mounting the lens 200 is molded of polycarbonate resin, and the mounting location is the lens window 300. The mounting portion of the lens window 300 has a pedestal 301 on which the lens 200 is installed.
fixing ribs 3 mm to 0.5 mm higher and thinner
02 is formed in the axial direction.

As shown in FIG. 8, the pedestal 3 of the lens window 300
01 after the lens 200 is installed, the heater unit 1
00 is brought into contact with the upper end of the fixing rib 302 while aligning the side wall 112 of the fixing rib 302 with the outer periphery of the fixing rib 302. In this state, the alternating current is applied between the A pole and the B pole from the secondary side of the winding transformer by the control time preset in the control circuit. A voltage was applied.

The fixing rib 302 is softened by the heat of the resistance heating element 110 which has generated heat. Further, the heater unit 100 is fixed to the fixing rib 302 with an appropriate force.
, The softened fixing rib 302
The portion higher than the height h of 00 is deformed along the inclined surface 113 of the resistance heating element 110, and finally is thermally deformed so as to be in close contact with the surface of the lens 200. This is shown in FIG.

After the set heating time and the remaining heat time have elapsed, when the solenoid valve is opened, compressed air serving as a cooling medium is sent into the pipe 123, and is blown from the pipe opening hole 127 at the end thereof to the resistance heating element 110, so that the resistance heating element 110 is opened. Was allowed to cool instantly. After the compressed air was blown onto the resistance heating element 110, it escaped to the outside through four ventilation holes 125 formed in the mounting plate 120, so that forced cooling could be performed efficiently.

As a result, the resistance heating element 110 immediately returned to room temperature, and the thermally deformed fixing rib 302 was cured while maintaining its shape. After that, even if the heater unit 100 is separated from the fixing rib 302, the fixing rib 302 is in close contact with the lens 200, and as shown in FIG.
00 could be fixed securely.

FIG. 11 introduces data obtained by measuring the temperature change of the contact surface 111. The measurement locations are shown in FIG. 11, the intermediate locations X1 and X2 between the connection terminals where the temperature of the contact surface 111 rises fastest and become the hottest, and the vicinity Y1 of each connection terminal where the temperature rises the slowest. , Y2 were measured. As a result, the temperature difference between the highest temperatures measured at four points was 23 ° C. The result of the fixing method according to the first embodiment is as follows.
As described above, since the temperature difference between the resistance heating elements was small, it was confirmed that a uniform welded state was obtained and that there was no problem in appearance.

[0027]

Comparative Example 1 Heater unit 100 used in Example 1
Of the electric wires 130, 131, 132 and 133, a voltage was applied between the opposing electric wire 130 (connection terminal 115) and the electric wire 132 (connection terminal 117). In other words, it means that the resistance heating element 110 is divided into two equal parts and a voltage is applied to that part.

In the control circuit for controlling the relay and the solenoid valve, the operation time starts as follows: [primary energization (heating) 0.8 seconds] → [energization stop (remaining heat) 0.5 seconds] → [2 Next energization (heating) 1 second] →
Fixing work was performed by setting [stop power supply (remaining heat) for 5 seconds] → [open solenoid valve (forced cooling) for 2 seconds] → finish. The difference between the set time and the first embodiment is that the current value flowing through the resistance heating element 110 is increased because the resistance heating element 110 is divided into two parts, and thus the heating time is set to be short because the heating element is red hot. .

FIG. 12 introduces data obtained by measuring the temperature change of the contact surface 111. The measurement locations are shown in FIG. 12, which are intermediate locations X'1 and X'2 between the connection terminals at which the temperature rises the fastest and have the highest temperature, and Y 'near each connection terminal at which the temperature rises slowly and has the lowest temperature. 1 and Y'2 were measured at four points.
As a result, the temperature difference between the highest temperatures measured at four points was 74 ° C.
Met. Such a temperature difference may cause non-uniformity of the welded state, or may cause the resin to be partially broken due to abnormal heating. In this comparative example, a slight whitening phenomenon was observed in a part of the welded portion.

[0030]

[Embodiment 2] In a second embodiment, a heat welding method for welding a molded article formed of a thermoplastic resin by sandwiching a resistance heating element on its joint surface and generating heat by the heat generation will be introduced. FIG. 13 is an assembled perspective view of completing the storage case 400 by heat-welding the case body 401 and the cover 402. Storage case 4
00 has an external dimension of about 300 × 150 × 40 (mm).

The case body 401 and the cover 402 are plastic molded products formed of a thermoplastic resin, and reference numeral 500 is a ring-shaped resistance heating element formed of a nickel-chromium alloy. The resistance heating element 500 includes the resistance heating element 50.
The semi-circular electrodes 501 and 50 are placed at the positions where the line length of 0 is divided into four equal parts.
2, 503 and 504 are formed, and the case body 401 is formed.
, Rounds 403, 404, 405, and 406 having substantially the same shape as the respective electrodes are formed at locations corresponding to the respective electrodes.
Is formed therein.

The resistance heating element 500 is incorporated in the groove 407,
The resistance heating element 50 is formed by the case body 401 and the cover 402.
FIG. 14 is a cross-sectional view of the round 403 portion sandwiching 0.
As shown in FIG.
Terminal guide hole 40 opening toward bottom surface 408 of
At the time of welding, a voltage application terminal 601 is inserted from the bottom surface 408 of the case main body 401 into the terminal guide hole 409 as shown in FIG. 15 to contact the electrode 501 formed on the resistance heating element 500 to apply a voltage. It is possible to apply. The other round sections have the same structure.

Next, the operation of the heat welding method in the second embodiment will be described with reference to FIG. After assembling the resistance heating element 500 into the groove 407 formed on the joint surface of the case body 401 formed of a thermoplastic resin, a cover 402 formed of a thermoplastic resin is put on.

Next, a voltage is applied to the resistance heating element 500, and the electrodes 501, 502, 503, and 504 are provided at positions where the line length of the resistance heating element 500 is divided into four equal parts.
In order to apply the same voltage to the other electrodes except for the adjacent electrode, the voltage applied to the electric wire connected to the voltage applying terminal 601 contacting the electrode 501 and the voltage applying terminal 603 contacting the electrode 503 as shown in FIG. Example 1 A-pole connected by connecting the connected electric wires, the electric wire connected to the voltage applying terminal 602 contacting the electrode 502 and the electric wire connected to the voltage applying terminal 604 contacting the electrode 504 to form the B-pole. The secondary winding was connected to the secondary side of the winding transformer described in (1).

Embodiment 1 for the primary side of the winding transformer
This is the same configuration as. The welding operation time in Example 2 was set as: start → [primary energization (heating) 2 seconds] → [energization stop (remaining heat) 1 second] → [secondary energization (heating) 1 second] → end.

It was confirmed that the storage case thermally welded by the method set as described above had a uniform welded state, and had no problem in appearance. Although the electrodes are formed on the resistance heating element, it is not necessary to form the electrodes if the structure is such that the voltage application terminal is surely in contact with the resistance heating element. In order to automatically carry out the second embodiment, welding can be easily performed by using a welding apparatus of Japanese Utility Model Application No. 9-9531 filed as a utility model filed by the present applicant.

[0037]

As described above, in the welding apparatus according to the present invention , the resistance heating element is formed in a ring shape, and a portion where the ring-shaped wire length is evenly divided is set as a power receiving portion. Since the other power receiving units except the power receiving unit have the same polarity, and a voltage is applied between the two poles set as described above to cause the resistance heating element to generate heat, the following effects are obtained.

A. Since the interval between the power receiving units of the resistance heating element can be shortened, there is no difference in the heat generation time between the power receiving units, so that the heat generation temperature distribution of the entire resistance heating element can be made uniform. b. When the wire length of the resistance heating element is increased, the conventional method has
When heat welding is performed at the power receiving portion of the pole, abnormal deformation due to heat or insufficient welding occurs on the contrary depending on the welding location. However, a uniform welding state can be obtained by using multiple power receiving portions. c. Since an AC voltage is used as the voltage applied to the resistance heating element, a simple power supply circuit is sufficient and the heat generation efficiency is good.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of a heater unit according to a first embodiment.

FIG. 2 is a sectional view taken along the line AA 'in FIG.

FIG. 3 is a diagram showing the completion of the main parts of the heater unit according to the first embodiment.

FIG. 4 is a completed view of the heater unit according to the first embodiment.

FIG. 5 is a plan view of the heater unit according to the first embodiment viewed from a contact surface.

FIG. 6 is a sectional view taken along the line BB ′ in FIG. 5;

FIG. 7 is a sectional view taken along the line CC ′ in FIG. 5;

FIG. 8 is a cross-sectional view of the fixing rib according to the first embodiment in a step of thermally deforming the fixing rib.

FIG. 9 is a sectional view of a cooling step of the fixing rib in the first embodiment.

FIG. 10 is a cross-sectional view showing the completion of fixing of the lens in the first embodiment.

FIG. 11 shows data obtained by measuring a change in temperature of the contact surface in Example 1.

FIG. 12 shows data obtained by measuring a temperature change of a contact surface in Comparative Example 1.

FIG. 13 is an explanatory view showing a state in which the case body and the cover according to the second embodiment are subjected to the heat welding method of the present invention using a resistance heating element.

FIG. 14 is a cross-sectional view of a round portion showing a state in which a resistance heating element is sandwiched between a case body and a cover.

FIG. 15 is a sectional view of a round portion in which a resin is melted by bringing a voltage application terminal into contact with an electrode of a resistance heating element.

FIG. 16 is a connection diagram showing a connection method of each voltage application terminal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 Heater unit 110 Resistance heating element 111 Contact surface 115,116,117,118 Connection terminal 130,131,132,133 Electric wire 200 Lens 300 Lens window 302 Fixing rib 400 Storage case 401 Case body 402 Cover 403,404,405 , 406 Round 409 Terminal guide hole 500 Resistance heating element 501, 502, 503, 504 Electrode 601, 602, 603, 604 Voltage application terminal

Continuation of the front page (56) References JP-A-8-211096 (JP, A) JP-A-56-53027 (JP, A) JP-A-56-80420 (JP, A) JP-A-63-194930 (JP, A) , A) Real opening 49-144869 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 65/00-65/82

Claims (1)

(57) [Claims] 1. A welding apparatus used for fixing a lens to a plastic base by thermally deforming a fixing rib of a plastic base formed of a thermoplastic resin.
Te, a resistive heating element the ribs thermally deformed to form a ring shape, the line length of the ring-shaped and receiving section a portion of an even number equal to a further receiving section different poles adjacent in the power receiving portion, the the voltage between the two poles which summarizes the same poles that are set as to mark pressurized by heating the resistance heating element by passing a current, the lens side fixing rib is pressed against it in the fixing rib A multi-pole voltage application method of fixing the lens to the plastic base by thermally deforming the lens is adopted.
After the fixing ribs have been thermally deformed,
Attach a pipe for blowing air for cooling
For welding thermoplastic resin molded products.