Fanless heat conduction type welding gun for plastics

Abstract

To provide a windless thermal conductive type welding gun for plastic that does not use hot wind.SOLUTION: A windless thermal conductive type welding gun for plastic comprises: a first heater in which a high thermal conductive attachment for heating a base material is detachably fixed, the attachment having a cylindrical portion formed to bring an inner circumferential surface into contact with an outer circumferential surface of the heater so as to be thermally conductible; a second heater provided with an attachment for heating a welding rod that forms a surface that brings a predetermined range on an outer circumferential surface of the welding rod into contact with itself, and placed in the vicinity of a tip portion of the attachment for heating a base material; and a controller that on / off-controls the first heater or the second heater by temperature information from a first thermometer that measures a temperature of the first heater and a second thermometer that measures a temperature of the second heater. A bottom-surface shape of the attachment for heating a base material forms a surface that can match a surface on which the base materials are joined. A surface with which the welding rod of the attachment for heating a welding rod is brought into contact is set at a height in the vicinity where the welding rod is grounded to the base material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a windless heat-conduction welding gun for plastics, which can be used for welding both general-purpose thermoplastic plastics such as polyvinyl chloride and fiber-reinforced plastics containing fibers such as carbon fiber, glass fiber, boron fiber, aramid fiber, polyethylene fiber, modified polyphenylene ether fiber and cellulose nanofiber. [Background Art]

[0002] Patent Document 1 discloses a plastic welding trowel for use in welding plastic welding materials, wherein a pressing roll provided with a guide groove in a circumferential direction is provided at a lower end portion, and a guide portion for guiding the welding material to a front side of the pressing roll is integrally formed on a support arm that connects the pressing roll to a handle portion. This is a welding method in which hot air is blown from a welding heater to heat a plastic welding material and a base material.

[0003] Patent Document 2 describes a welding material supply pipe provided in the nozzle section from which a first welding material is supplied, and gas is supplied from the gas supply section to a hot air supply pipe containing a ceramic heater, the gas is heated by the ceramic heater to become hot air, the hot air is sent to a hot air discharge pipe connected to the hot air supply pipe, introduced into a hot air introduction pipe provided in the nozzle section and connected to the hot air discharge pipe, the first welding material is heated, pressed and softened by spraying the hot air in the longitudinal direction from the tip to the rear end by a roller provided in the nozzle section, and then the roller is returned to the tip of the first welding material and a part of the width direction overlaps the first welding material. A welding method for resin, glass fiber reinforced plastic (GFRP), carbon fiber reinforced plastic (CFRP), or carbon material is disclosed, comprising: supplying a second welding material in such manner; melting the overlapping portion of the first welding material and the second welding material by spraying hot air; applying pressure in the longitudinal direction from the leading edge to the trailing edge of the overlapping portion of the first welding material and the second welding material by a roller provided in the nozzle to press and integrate the overlapping portion of the first welding material and the second welding material; and cooling the overlapping portion of the first welding material and the second welding material by supplying cooling air from a cooling pipe provided in the nozzle.

[0004] Patent Document 3 discloses a plastic welding method in which a welding rod is applied to the welded portion of a member to be welded, and the welded portion is heated and melted by hot air blown from a welding device to weld the plastic welding method, characterized in that a first heating means substantially melts the welded portion of the member to be welded, and then a second heating means maintains the molten welded portion at a temperature that does not fall below the melting point of the member to be welded, while simultaneously heating and melting the welding rod, and the wave welded portion of the member to be welded in this state is welded with the welding rod. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-174677 [Patent Document 2] Patent No. 5883235 [Patent Document 3] Japanese Patent Application Publication No. 2-92520 [Overview of the project] [Problems that the invention aims to solve]

[0006] The inventions described in Patent Documents 1 to 3 involve melting the base material and welding rod with hot air, which can easily lead to variations in welding strength depending on how the hot air is applied to the base material and welding rod. Furthermore, the application of hot air to the base material and welding rod requires skilled technique, resulting in a considerable training period for plastic welding workers to become proficient.

[0007] Furthermore, paragraph 0035 of Patent Document 1 states that in the case of carbon fiber plastics, the temperature must be raised to approximately 800 to 2000°C to weld these fibers. However, there was a problem in that workers had to perform welding work with hot air heated to a high temperature of 2000°C, which posed a risk of burns. In addition, since the melting points of resins are, for example, 130°C for polyethylene and 170°C for polypropylene, the carbon fibers themselves do not melt, but the resin that has the function of bonding melts or evaporates, deteriorates, or the resin component disappears, leaving only the fibers. This resulted in a quantitative shortage of the resin with the bonding function essential for welding, making welding impossible.

[0008] This invention was conceived in view of these problems, and aims to provide a windless heat conduction type welding gun for plastics that eliminates the need for hot air welding, provides welding quality with less variation in welding strength, and shortens the training period to become a fully competent operator. [Means for solving the problem]

[0009] The windless heat conduction type welding gun for plastics described in claim 1 is a windless heat conduction type welding gun for welding plastic base materials together, and the plasticThe base material can be heated to a temperature that melts it, and then joined. The aforementioned plastic A first heater is provided, which is a cylindrical body having an outer surface with a bottom shape that can contact each joining surface of the base material, and is inserted into a base material heating attachment with high thermal conductivity, with the outer surface in surface contact, and the base material heating attachment is detachably fixed to it; a second heater is provided, which is capable of raising the temperature to a temperature that melts the welding rod, has a surface that contacts a predetermined range of the outer surface of the welding rod in the circumferential direction, and is disposed near the tip of the base material heating attachment; a first thermometer for measuring the temperature of the first heater; a second thermometer for measuring the temperature of the second heater; and based on the temperature information from the first and second thermometers, the first heater or The aforementioned The device comprises a control unit that controls the on / off state of each second heater, wherein the tip of the first heater is inserted into the base material heating attachment up to near the tip of the cylindrical portion of the base material heating attachment, and the lower end of the portion of the welding rod heating attachment that contacts the welding rod is provided within the range of the base material heating attachment in the height and left / right directions, but not in contact with the base material.

[0010] The windless heat conduction type welding gun for plastics according to claim 2 is characterized in that, according to claim 1, a predetermined range in the circumferential direction of the outer surface of the welding rod is set to any range from about 1 / 4 to about 3 / 4 of the circumferential direction of the outer surface of the welding rod.

[0011] The windless heat conduction type welding gun for plastics according to claim 3 is characterized in that, according to claim 1 or 2, the heating temperature of the first heater is set to a temperature above the melting point of the base material and near the melting point, and the heating temperature of the second heater is set to a temperature above the melting point of the welding rod and near the melting point.

[0012] The windless heat conduction type welding gun for plastics described in claim 4 is: Claim 1 The welding apparatus is characterized in that, in the direction of welding, a pressing body is provided on the rear side of the second heater for pressing the molten portion of the welding rod and the molten portion of the base material, which are filled between the respective joining surfaces of the base material.

[0013] The windless heat conduction type welding gun for plastics described in claim 5 is characterized in that, in the direction of welding, it is provided with a pressing body on the rear side of the second heater, which presses the molten portion of the welding rod and the molten portion of the base material, which are filled between the respective joining surfaces of the base material. [Effects of the Invention]

[0014] The invention described in claim 1 does not use hot air welding, which requires skills such as adjusting the distance between the hot air nozzle and the base material and accurately controlling the area to which the hot air is applied. Instead, it is possible to heat and melt the base material and welding rod by applying a heating element to them through heat conduction, resulting in a welding quality with small variations in welding strength. Furthermore, since it only requires applying a heating element to the base material and welding rod, it also has the effect of allowing for early training of skilled workers.

[0015] Even if the angles and shapes of the joining surfaces of the two base materials to be joined differ, the detachable base material heating attachment can be replaced with one that can make surface contact with the joining surface of the base materials. Therefore, regardless of the angle of inclination formed by the joining surfaces of the two base materials to be joined, the system can be easily adapted by replacing the base material heating attachment.

[0016] The invention described in claim 2 has the effect of preventing welding defects such as voids and pinholes from occurring while ensuring welding strength, as heating the outer surface of the lower end of the welding rod over its entire circumference in the circumferential direction would cause the lower end of the welding rod to melt over its entire circumference, making it difficult to press the molten portion of the lower end of the welding rod against the molten portion of the base material. However, by making the second heater contact the welding rod for only about half of its circumference in the circumferential direction, the welding rod is divided into about half of the circumference in the circumferential direction where it contacts the heating element and melts, and about half of the circumference in the circumferential direction where it does not melt because it does not contact the heating element. This allows the remaining non-molten portion of the welding rod to be pressed downwards and bent like a waist, thus enabling the molten portion of the welding rod to be pressed against the molten portion of the base material.

[0017] The invention according to claim 3 adapts to the fact that the heating temperature required for melting the joint surface of the base material and the heating temperature required for melting the welding rod differ due to differences in materials and the like, so that optimal heating temperatures can be separately set for melting the base material and melting the welding rod, respectively. For example, in the case of fiber-reinforced plastic, the heating temperature for melting the base material tends to be higher than the heating temperature for melting the welding rod. Therefore, if the welding rod is heated at a heating temperature suitable for the base material, the welding rod will melt more than necessary, which causes a problem that it becomes difficult to press the welding rod against the molten portion of the base material. However, since the heating temperatures of the base material and the welding rod can be controlled separately, the molten portion of approximately half the circumference in the circumferential direction of the lower end of the welding rod can be pressed against the molten portion of the surface layer which is the joint surface of the base material, which produces the effect that welding defects such as voids and pinholes do not occur and welding strength can be ensured.

[0018] The invention according to claim 4 produces the effect that the quality of welding strength can be further stabilized since the molten portion of the welding rod is further pressed against the molten portion of the surface layer of the joint surface of the base material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [Figure 1] It is a configuration explanatory diagram of the windless heat-conduction plastic welding gun of the present invention. [Figure 2] It is an explanatory diagram in which a welding rod is attached to the windless heat-conduction plastic welding gun of the present invention. [Figure 3] It is an explanatory diagram of the A-A cross-section in Fig. 1, wherein (a) is an explanatory cross-sectional view of a portion of the base material heating attachment, and (b) is an explanatory view of a state where the base material heating attachment is inserted into the joint surface which is the groove surface in the case of a butt joint. [Figure 4] It is a longitudinal cross-sectional explanatory view of part B in Fig. 1. [Figure 5] It is a transverse cross-sectional view of part E in Fig. 1, wherein (a) is an explanatory view showing a state where the second heater is disposed on the left and right sides of the welding rod as shown in Fig. 1, and (b) is an explanatory view showing a state where, although not illustrated, the second heater is disposed on the front side in the front-rear direction of the welding rod, that is, on the first heater side. [Figure 6]It is an explanatory diagram of a comparative example, and is an explanatory diagram of a form in which a base material and a welding rod are melted by a single heater. [Figure 7] It is a cross-sectional explanatory diagram of portion C in FIG. 6. [Figure 8] It is an explanatory diagram of joint surfaces of base materials in the case of a butt joint, wherein (a) is an explanatory diagram showing a state where two base materials are butted at the joint surfaces, and (b) is an explanatory diagram of a D-D cross-section of (a). [Figure 9] It is an explanatory diagram showing a state before welding work, in which the windless heat-conduction type welding gun for plastics of the present invention is applied to the joint surface shown in FIG. 8. [Figure 10] It is an explanatory diagram showing a state during welding work performed by the windless heat-conduction type welding gun for plastics of the present invention. [Figure 11] It is an explanatory diagram of a molten state of a surface layer of a joint surface during welding in the case of a butt joint, wherein (a) is an explanatory diagram showing a state where a molten portion of a welding rod is pressed against the molten surface layer of the joint surface by a non-molten portion of the welding rod, and (b) is an explanatory diagram showing a state after the non-molten portion of the welding rod shown in (a) is pressed by a pressing body. [Figure 12] It is an external appearance explanatory diagram of the windless heat-conduction type welding gun for plastics when the pressing body is in the form of a roller. [Figure 13] It is an external appearance explanatory diagram of the windless heat-conduction type welding gun for plastics when the pressing body is in the form of a spatula. MODE FOR CARRYING OUT THE INVENTION

[0020] In plastic welding, a worker typically holds a hot air jet device in one hand and a welding rod in the other, melting the base material 20 and the welding rod 30 with hot air to weld the plastic base material 20. However, while welding plastics with melting points up to around 200°C, such as polyvinyl chloride (85°C) and nylon 6 (225°C), is possible for workers, the melting point of fiber-reinforced plastics containing fibers such as carbon fiber, glass fiber, boron fiber, aramid fiber, polyethylene fiber, modified polyphenylene ether fiber, and cellulose nanofiber increases as the fiber content increases, reaching, for example, 400°C. In such cases, the hot air becomes too hot, posing a risk of burns and other accidents during welding by a worker.

[0021] Therefore, the inventor worked to develop a plastic welding gun that does not use hot air, which can cause burns, in order to create an environment in which workers can safely weld plastics and obtain welding quality with little variation in welding strength. He came up with the idea of ​​a windless heat conduction type plastic welding gun that can weld plastics by heat conduction without wind.

[0022] The windless heat conduction type plastic welding gun 1 of the present invention is as shown in Figure 1, Figure 2, Figure 4, or Figure 10, A windless heat conduction type plastic welding gun 1 for welding plastic base materials 20a and 20b together, comprising: a first heater 2 which is inserted into a base material heating attachment 5 with a cylindrical outer surface having a bottom shape 5a that can raise the temperature to a temperature at which the base materials 20a and 20b are to be joined, with the outer surface in surface contact with the base material heating attachment 5 and the base material heating attachment 5 being detachably fixed; and a welding rod heating attachment 6 which is positioned near the tip of the base material heating attachment 5, and has a surface that can raise the temperature to a temperature at which the welding rod 30 is to be melted, and has a surface that contacts a predetermined range of the outer surface of the welding rod 30 in the circumferential direction. The assembly comprises a second heater 3, a first thermometer 7 for measuring the temperature of the first heater 2, a second thermometer 8 for measuring the temperature of the second heater 3, and a control unit 9 that controls the on / off state of the first heater 2 or the second heater 3 based on temperature information from the first thermometer 7 and the second thermometer 8, respectively. The tip of the first heater 2 is inserted into the base material heating attachment 5 up to near the tip of the cylindrical part of the base material heating attachment 5, and the lower end of the part of the welding rod heating attachment 6 that contacts the welding rod 30 is provided within the height and left / right range of the base material heating attachment 5, but within a range that does not contact the base material 20.

[0023] The shapes formed by the joint surfaces 21a and 21b of the base materials 20a and 20b to be joined vary depending on the type of joint used to join the base materials 20a and 20b. Examples include butt joints where the ends of two base materials are joined together, T-joints where two base materials are joined in a T-shape, L-joints where two base materials are joined in an L-shape, and lap joints where two base materials are joined face to face. In the case of a butt joint, the joint surfaces 21a and 21b form a grooved surface, as shown in Figures 8(a) and (b).

[0024] As shown in Figures 1, 2, or 4, the windless heat conduction type welding gun 1 for plastics of the present invention comprises a handle 11, a first heater 2 fixed to the handle 11 via a heater support 4 for base material heating and detachably fixed to a base material heating attachment 5, a first thermometer 7 for measuring the temperature of the first heater 2, a second heater 3 equipped with a welding rod heating attachment 6, a second thermometer 8 for measuring the temperature of the second heater 3, a commercial power supply (not shown), a control unit 9 connected to the first thermometer 7, the second thermometer 8, the first heater 2, and the second heater 3, and controlling the on / off status of the first heater 2 and the second heater 3. The second heater 3 is fixed to the handle 11 via a support arm 10.

[0025] The operator can perform plastic welding by holding the handle 11 to which the first heater 2 and the second heater 3 are fixed in one hand, holding the welding rod 30 in the other hand, and moving the base material heating attachment 5 while pressing it against the joint 21a, 21b of the base materials 20a, 20b, as shown in Figure 8(a), as shown in Figure 9 or Figure 10.

[0026] First, the first heater 2 is, for example, a cartridge heater, and is fixed to a cylindrical base material heating heater support 4 that extends downward from the handle 11. It is inserted into the cylindrical portion of a base material heating attachment 5, which has a high thermal conductivity and is formed to make heat conduction-enabled contact. The outer surface of the first heater 2 is in close contact with or in contact with the inner surface of the base material heating attachment 5 and is fixed detachably by fixing means 15 such as bolts.

[0027] The heating wire 12a of the first heater 2 is connected to the control unit 9 by passing through the first heater 2, the base material heating heater support part 4, and the hollow part inside the handle 11.

[0028] As shown in Figures 3(a) or (b) and 4, the outer surface of the cylindrical first heater 2 is shaped to be in full contact with the inner surface of the cylindrical base material heating attachment 5. The tip of the first heater 2 is inserted to the tip of the hollow portion of the cylindrical base material heating attachment 5, so that the entire bottom surface 5a of the base material heating attachment 5 that contacts the base material 20 can be heated to a temperature that melts the base materials 20a and 20b. By inserting it to the tip, the entire length of the base material heating attachment 5 can be heated, and the surface layers of the joint surfaces 21a and 21b of the base materials 20a and 20b can be melted up to the position where the molten portion of the welding rod 30 is pressed against it.

[0029] The shape of the bottom surface 5a of the base material heating attachment 5 that contacts the joint surfaces 21a, 21b of the base materials 20a, 20b is such that, for example in the case of a butt joint, it makes full contact with the inclined surfaces of the joint surfaces 21a, 21b of the base materials 20a, 20b, as shown in Figures 3(a) and (b). Therefore, when the groove angle is 30°, an attachment with a bottom surface inclination angle of 30° is prepared, and when the groove angle is 45°, an attachment with a bottom surface inclination angle of 45° is prepared, and the base material heating attachment 5 can be replaced to correspond to the groove angle of the joint surfaces 21a, 21b. When replacing, it can be easily replaced as it is detachably fixed by fixing means 15 such as bolts.

[0030] The first heater 2 can be set to heat up to accommodate both the welding of plastics such as nylon 6, where the optimal welding temperature is around 200°C, and the welding of fiber-reinforced plastics containing fibers such as carbon fiber, glass fiber, boron fiber, aramid fiber, polyethylene fiber, modified polyphenylene ether fiber, and cellulose nanofiber, where the optimal welding temperature is between 150°C and 700°C.

[0031] If the base material 20 is a fiber-reinforced plastic, since fiber-reinforced plastic is a mixture of fibers such as carbon fibers or glass fibers and thermoplastic general-purpose plastics such as polyvinyl chloride or nylon 6, the optimal melting temperature for welding increases as the content of the non-melting fibers increases. On the other hand, the welding rod 30 is not necessarily made with the same fiber content as the base material 20. For example, if the base material 20 is a fiber-reinforced plastic with a fiber content of 40% by weight, a plastic welding rod 30 that does not contain fibers or a plastic welding rod 30 with a fiber content of 10% by weight may be used. Therefore, the melting temperature required for welding the welding rod 30 may be lower than the optimal melting temperature for welding the base material 20.

[0032] For example, as shown in Figure 6 or Figure 7, if the heating element is only equipped with a first heater 2, the welding operation is performed by moving the base material heating attachment 5b while pressing it against the joint surfaces 21a, 21b of the base material 20, and pressing the welding rod 30 downwards while applying it to the welding rod heating attachment 6a. In this case, the temperature measurement is taken by measuring the temperature of the first heater 2. In the case of such a plastic welding gun, the heating temperature of the base material 20 and the heating temperature of the thermoplastic general-purpose plastic welding rod are the same.

[0033] As in the comparative example above, when the heating temperature for a fiber-reinforced plastic base material 20 with a fiber content of 40% by weight is the same as the heating temperature for a thermoplastic general-purpose plastic welding rod that does not contain fibers, when the base material 20 is heated to the temperature at which it melts, the surface layer of the joint surface 21 of the base material 20 melts to an appropriate depth, while the lower end of the welding rod 30 melts over its entire circumference due to high-temperature heat conduction, even if only about half of the circumference of the welding rod heating attachment 6a is in contact with the welding rod heating attachment 6a. As a result, the welding rod cannot be pressed against the molten portion of the surface layer of the joint surface 21 of the base material 20, welding defects such as voids and pinholes are likely to occur, making it difficult to obtain sufficient welding strength.

[0034] In contrast, in the case of the windless heat conduction type plastic welding gun 1 of the present invention, the heating temperatures of the first heater 2 that heats the base material 20 and the second heater 3 that heats the welding rod 30 are set separately. As shown in Figure 10, even if approximately half the circumference of the welding rod 30 is brought into contact with the welding rod heating attachment 6, the temperature is not excessively high, so only approximately half the circumference melts, leaving the remaining approximately half unmelted. This allows the welding rod 30 to be pressed against the molten portion of the surface layer of the joint surface 21 of the base material 20, resulting in stable welding strength without generating welding defects such as voids or pinholes.

[0035] In other words, the heating temperature of the first heater 2 can be set to a temperature near the melting temperature, which is above the optimal melting temperature for welding the base material 20, and the heating temperature of the second heater 3 can be set separately to a temperature near the melting temperature, which is above the optimal melting temperature for welding the welding rod 30, and these temperatures can be maintained.

[0036] Furthermore, the first heater 2 is, for example, an electric heater capable of heating up to approximately 700°C, and the second heater 3 is, for example, an electric heater capable of heating up to approximately 700°C. The first heater 2 or the second heater 3 could be, for example, a cartridge heater in which a nichrome wire, which is the heating element, is covered with a metal pipe made of a material with high thermal conductivity such as stainless steel, titanium, or copper.

[0037] Next, the second heater 3 is, for example, a cartridge heater, fixed to a support means 10 extending from the handle 11, capable of raising the welding rod 30 to the optimal melting temperature for welding, forming a surface that contacts a predetermined range of the outer surface of the welding rod 30, and detachably fixed to a welding rod heating attachment 6 disposed near the tip of the base material heating attachment 5. By placing it in this vicinity, for example, in the case of a butt joint, the molten portion of the lower end of the welding rod 30 can be pressed against the molten portion of the surface layer of the joint surfaces 21a and 21b of the base materials 20a and 20b to join them.

[0038] The heating wire 12b of the second heater 3 is connected to the control unit 9 by passing through the cavity of the support arm 10 and the cavity of the handle 11 from the second heater 3.

[0039] The predetermined circumferential range of the outer surface of the welding rod 30 is set to a range of approximately 1 / 4 to approximately 3 / 4 of the circumferential range of the outer surface of the welding rod 30, as shown in Figures 5(a), 5(b), 10, or 11. This range is the heating range of the welding rod 30 and the range in which the welding rod 30 melts. For example, if the welding rod heating attachment 6 is provided so as to surround the entire circumference of the outer surface of the welding rod 30 in the circumferential direction, the entire circumference of the welding rod 30 will melt, and the lower end of the welding rod 30 that is in contact with the welding rod heating attachment 6 will melt completely. As a result, it will become impossible to push the lower end of the welding rod 30 into the joint surface 21 of the base material 20, and welding defects such as voids and pinholes will occur, making it difficult to secure welding strength. Therefore, by heating approximately half of the circumference of the outer surface of the welding rod 30 and leaving the other half unheated, an unmelted portion 31 can be achieved. This allows the melted portion of the lower end of the welding rod 30 to be pushed towards the melted portion of the joint surface 21 of the base material 20, thereby obtaining the necessary welding strength.

[0040] The range of approximately 1 / 4 to approximately 3 / 4 of the circumferential surface of the welding rod 30 depends on the diameter and material of the welding rod 30. The range is set such that approximately half of the circumferential surface of the welding rod 30 is melted and the other half is left as an unmelted portion 31, allowing the unmelted portion 31 at the lower end of the welding rod 30 to push the molten portion at the lower end of the welding rod 30 into the joint surface 21 of the base material 20. Furthermore, as shown in Figure 11(a), it is necessary that the unmelted portion 31 be smaller than the width of the joint surface 21. Therefore, the range of approximately 1 / 4 to approximately 3 / 4 of the circumferential surface of the welding rod 30 is set to satisfy this requirement.

[0041] Furthermore, the welding rod heating attachment 6 can be configured as shown in Figure 5(a), in which the welding rod 30 is positioned laterally from the second heater 3 and on the rear side R of the first heater 2, or as shown in Figure 5(b), in which the welding rod 30 is positioned on the rear side R of the second heater 3 and on the rear side R of the first heater 2.

[0042] The lower end of the portion of the welding rod heating attachment 6 that contacts the welding rod 30 is positioned within the height and left-right range of the base material heating attachment 5, but not in contact with the base material 20. The height and left-right range of the base material heating attachment 5 is, in other words, directly above the joint surfaces 21a and 21b of the two base materials 20a and 20b, and corresponds to the height near where it makes contact with the base materials 20a and 20b. Positioning the lower end of the portion of the welding rod heating attachment 6 that contacts the welding rod 30 at a height near where it makes contact with the base materials 20a and 20b is to prevent the temperature of the molten portion of the base material 20 from decreasing due to air cooling and the temperature of the molten portion of the welding rod 30 from decreasing due to air cooling, which would prevent joining by melting, if the distance from the lower end of the heated welding rod 30 to the heated base material 20 becomes long.

[0043] Next, the first thermometer 7 is attached to the outer surface of the base material heating attachment 5 to measure the temperature of the first heater 2, and the second thermometer 8 is attached to the outer surface of the second heater 3 to measure the temperature of the second heater 3. The first thermometer 7 or the second thermometer 8 is preferably capable of extracting the acquired temperature information as an electrical signal, such as a thermocouple.

[0044] The first thermometer 7 and the control unit 9 are connected by wiring 13a, and the electrical signal of temperature information from the first thermometer 7 is transmitted to the control unit 9 via wiring 13a. The second thermometer 8 and the control unit 9 are connected by wiring 13b, and the electrical signal of temperature information from the second thermometer 8 is transmitted to the control unit 9 via wiring 13b.

[0045] Next, as shown in Figure 1 or Figure 2, the control unit 9 is connected to the first heater 2 by wiring 12a, to the second heater 3 by wiring 12b, to the first thermometer 7 by wiring 13a, to the first thermometer 7 by wiring 13b, and to the commercial power supply. The control unit 9 sets the optimal welding temperature for the first heater 2 and the second heater 3, respectively, and then controls the power supply on and off based on temperature information from the first thermometer 7 and the second thermometer 8 in order to maintain the set temperature of the first heater 2 or the second heater 3.

[0046] Next, the pressing body 18 will be described. The pressing body 18 presses the molten portion of the welding rod 30 and the molten portion of the base material 20, which are filled between the joint surfaces 21 of the base material 20, against the rear side R of the second heater 3 in the direction of welding. The pressing body 18 can be a roller type 18a as shown in Figure 12, or a spatula type 18b as shown in Figure 13, and any form is acceptable as long as it can press the molten portion of the welding rod 30 filled between the joint surfaces 21 of the two base materials 20. If the pressing body 18 is a roller type 18a, it is rotatably fixed to a support arm 19 protruding from the support arm 10, and if it is a spatula type 18b, it is fixed to a support arm 19 protruding from the support arm 10.

[0047] As shown in Figures 9, 10, or 11(a), the roller configuration 18a presses downwards the unmelted portion 31 on the surface of the molten welding rod 30, which is filled between the joining surfaces 21 of the two base materials 20 and protrudes above the surface of the base materials 20, against the rear side R of the second heater 3. This presses the joint from the state shown in Figure 11(a) to the state shown in Figure 11(b), compressing the molten portion of the welding rod 30 and the molten portion of the base material 20 to create a stronger bond.

[0048] Next, an example of using the fanless heat conduction type plastic welding gun 1 will be described. First, as shown in Figures 8(a) and (b), the case where the base material 20 is a butt joint will be described. When butt welding base material 20a and base material 20b, joint surfaces 21a and 21b, i.e., groove surfaces, are formed on each. The base material heating attachment 5 of the fanless heat conduction type plastic welding gun 1 is attached in a shape that can make full contact with the inclined surface of the joint surface 21.

[0049] Next, the temperature setting means of the control unit 9 is used to set the temperatures of the first heater 2 and the second heater 3, taking into consideration the material of the base material 20 and the material of the welding rod 30. Then, the handle 11 is grasped with one hand, the power of the control unit 9 is turned on, and the first heater 2 and the second heater 3 are energized to start heating. After the heating temperature of the first heater 2 and the second heater 3 reaches the set temperature, as shown in Figures 3(a) and (b), the bottom surface 5a of the base material heating attachment 5 of the first heater 2 is pressed against the joint surfaces 21a and 21b, which are the groove surfaces of the base materials 20a and 20b, so that they are in surface contact. As shown in Figure 9 or Figure 10, the welding rod 30 is grasped with the other hand and its lower end is brought into contact with the welding rod heating attachment 6 of the second heater 3.

[0050] Next, as shown in Figure 10, the base material heating attachment 5 is pressed against the joint surface 21, which is the groove surface, and advanced in direction X. At the same time, the welding rod 30 is brought into contact with the welding rod heating attachment 6 and gradually pressed downwards, i.e., in direction Z, in accordance with the speed at which the molten portion of the welding rod 30 fills the gap between the joint surfaces 21, which is the groove surface.

[0051] As a result, as shown in Figure 10 or Figure 11(a), the surface layer of the joint surface 21 in the area L2 that is in contact with the base material heating attachment 5 and heated by heat conduction is heated and melted. Note that the joint surface 21 in area L1 is shown in its original state for comparison with the welded portion.

[0052] Furthermore, as shown in Figure 10, the welding rod 30, with approximately half of its circumference melted by contact with the welding rod heating attachment 6 and the remaining approximately half of its circumference remaining unmelted, can be pressed against the molten surface layer of the joint surfaces 21a and 21b, which are the groove surfaces of the base material, while bending the portion with the unmelted portion 31. As shown in Figure 11(a), the shape of the molten portion T after pressing is such that the molten portion T rises above the surface of the base material 20 in the heated joint surface 21 area L3. By pressing the molten portion of the welding rod 30 against the molten surface layer of the base material 20 in this raised area L3, the molten surface layer of the base material 20 and the molten portion of the welding rod 30 are firmly joined and welded together.

[0053] Then, in range L4, by applying pressure with, for example, the roller form 18a of the pressing body 18, and further pressing the molten portion of the welding rod 30 against the molten portion of the base material 20 as shown in Figure 11(b), plastic welding with even less variation in welding strength can be achieved.

[0054] Next, the tensile strength of welding performed by the same operator was compared between welding using a conventional hot-air plastic welding machine and plastic welding using the windless heat conduction type plastic welding gun 1 of the present invention. In both cases, the pressing body 18 was not used. The results are shown in Table 1. The welding rod 30 used was a thermoplastic carbon fiber reinforced plastic welding rod 30 (rod diameter 3 mm) containing 3% or 10% by weight of carbon fiber. Table 1 shows the tensile test results at a tensile speed of 50 mm / min when two test pieces, each 20 mm wide, 30 mm long, and 2 mm thick, with a carbon fiber content of 40% by weight (with the thermoplastic carbon fiber reinforced plastic member being 100% by weight), were butt-welded together. Tensile strength was tested as the welding strength.

[0055] [Table 1]

[0056] Table 1 shows that when the carbon fiber content is 3% by weight, the standard deviation when using a conventional hot air welding gun is 9.4, while when using the windless heat conduction plastic welding gun 1 of the present invention, the standard deviation is 3.2, reducing the variation by approximately 66%. When the carbon fiber content is 10% by weight, the standard deviation when using a conventional hot air welding gun is 7.7, while when using the windless heat conduction plastic welding gun 1 of the present invention, the standard deviation is 4.0, reducing the variation by approximately 48%. This reduction in variation indicates that the variation in welding quality due to the welding skills of the welder can be reduced, which has the effect of enabling new workers to be trained to become proficient in welding more quickly. In addition, since a tensile strength of 20 MPa or more is sufficient, the welding quality is not a problem in any case. [Explanation of symbols]

[0057] 1. Fanless heat conduction type plastic welding gun 2. First heater 3. Second heater 4. Heater support section for heating the base material 5. Attachment for heating the base material 5a Bottom 5b Attachment for heating the base material 6. Attachment for heating welding rods 6a Attachment for heating welding rods 7 First thermometer 8 Second thermometer 9. Control Unit 10 Support Arms 11 Handle 12 Wiring 13 Wiring 15 Fixing means 18 Pressing body 18a Roller form 18b Spatula form 19 Support Arm 20 Base material 21 Joint surface 30 welding rods 31 Non-molten part L range T molten section R rear side X direction Z direction

Claims

1. A windless heat conduction type plastic welding gun for welding plastic base materials together, A first heater is provided, which is a cylindrical body having an outer surface with a bottom shape that can contact each of the joining surfaces of the plastic base material to be joined, and which is inserted into a base material heating attachment with high thermal conductivity, with the outer surface in surface contact with the base material heating attachment, and which is detachably fixed to the base material heating attachment. A second heater is provided, which is capable of raising the temperature of the welding rod to a melting temperature, and which has a surface that contacts a predetermined area in the circumferential direction of the outer surface of the welding rod, and which is provided near the tip of the base material heating attachment, A first thermometer for measuring the temperature of the first heater, A second thermometer for measuring the temperature of the second heater, The system includes a control unit that controls the on / off state of the first heater or the second heater, respectively, based on temperature information from the first thermometer and the second thermometer, The first heater is inserted into the base material heating attachment up to the vicinity of the tip of the cylindrical portion of the base material heating attachment. A windless heat conduction type welding gun for plastics, characterized in that the lower end of the portion of the welding rod heating attachment that contacts the welding rod is provided within the range of the base material heating attachment in the height direction and left-right direction, but not in contact with the base material.

2. The windless heat conduction type welding gun for plastics according to claim 1, characterized in that a predetermined range in the circumferential direction of the outer surface of the welding rod is set to any range from about 1 / 4 to about 3 / 4 of the circumferential direction of the outer surface of the welding rod.

3. The windless heat conduction type welding gun for plastics according to claim 1 or 2, characterized in that the heating temperature of the first heater is set to a temperature above the melting point of the base material and near the melting point, and the heating temperature of the second heater is set to a temperature above the melting point of the welding rod and near the melting point.

4. The windless heat conduction type welding gun for plastics according to claim 1, characterized in that, in the direction of welding, the second heater is provided with a pressing body that presses the molten portion of the welding rod and the molten portion of the base material, which are filled between the respective joining surfaces of the base material.

5. The windless heat conduction type welding gun for plastics according to claim 3, further comprising a pressing body that presses the molten portion of the welding rod and the molten portion of the base material, which are filled between the respective joining surfaces of the base material, on the rear side of the second heater in the direction of welding.

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