JPS5810392A - Microwave heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave heating device, and more particularly to a microwave heating device that intensively heats a predetermined portion of an object to be heated.

The conventional method for bonding heated objects made of wood, plastic, etc. is to apply an adhesive that dries at room temperature to the joint surface of the heated objects and leave it to dry.

Alternatively, there was a method of applying a thermosetting adhesive to the joint surface and bonding with hot air.

Incidentally, in recent years, microwave heating devices that utilize dielectric heating using microwaves have been used for the purpose of shortening bonding time.

A conventional device of this type is shown in FIG.

That is, in the figure, reference numeral 1 denotes an object to be heated, which is a cabinet-like rectangular parallelepiped made of wood with six sides, each of which has a thermosetting adhesive applied to its ridgeline.

A waveguide 3 guides microwaves emitted from the microwave generator 2 into the heating chamber 4 .

In the microwave heating device having such a configuration, microwaves generated by the microwave generator 2 propagate within the waveguide 3, form an electromagnetic field within the heating chamber 4, and dielectrically heat the object 1 to be heated.

Generally, the thermosetting adhesive applied to the ridgeline of the object to be heated is selected from a material that is more easily dielectrically heated than the wood, plastic, etc. that form the object to be heated.

However, the degree of dielectric heating of wood, plastic, etc.
In other words, the dielectric constant cannot be ignored compared to that of adhesives, and they generate heat and reach high temperatures.Coupled with their large volume, they have the drawback of consuming a large amount of power, which is hardly involved in adhesion. .

In addition, when the thermosetting adhesive hardens, the object to be heated 1 made of wood or plastic is heated as described above, so residual stress is generated after bonding, resulting in a problem that the strength of the product is reduced. Ta.

Therefore, in view of the above-mentioned conventional situation, the present invention solves the above-mentioned conventional drawbacks and problems by providing a structure in which a predetermined part of the object to be heated is heated intensively.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 2 to 4.

In the figure, reference numeral 5 denotes a wooden cabinet as an object to be heated, and a thermosetting adhesive 7 is applied to the ridgeline joint surface of a wooden cabinet component 6, and is fixed with a clamping jig 17. Reference numeral 8 denotes a microwave radiator, which is composed of a microwave generator 10 and a microwave radiator 9.

Note that this microwave generator 10 is constructed from parts of a household microwave oven.

The microwave radiating section 9 is a rectangular waveguide with a cross section aXb that propagates microwaves with a frequency of 2450 (MH2) emitted from the microwave generator 1O, and the opposite tip opening edges on the - side are A notch groove 2A having a right-angled isosceles triangular shape is formed, and the apex thereof having a right angle is located at the center of the length a on the eight faces, forming a recess 9A. 1
1 is a conveyor for carrying in the wooden cabinet 5, 12 is a conveyor for carrying out the wooden cabinet, 12 is a conveyor for carrying it out, 4. B is a conveyor serving as a support device for placing and supporting objects to be heated in a radio wave shielding chamber, which will be described later.

Reference numeral 16 denotes a radio wave shielding room that houses the wooden cabinet 5, the microwave radiator 8, and the conveyor 12, and that shields leakage radio waves from the microwave radiator 9. Doors 14 and 15 for carrying in and out are provided. ing.

According to the microwave heating device having such a configuration, the wooden cabinet 5 transported by the transport conveyor 11 is transported into the radio wave shielding room 16 through the transport door 14 provided in the room 16 .

Then, as shown in FIG. 3, the four parts 9A of the microwave radiator 9 come as close as possible to the ridgeline of the wooden cabinet 5, and this is done by a microwave radiator operating device (not shown), and the microwave radiator They are dielectrically heated and bonded by microwaves emitted from 8.

The portions of the ridgeline portion of the wooden cabinet 5 to be dielectrically heated and bonded may have sufficient strength to withstand the work in the next step.

At this time, as shown in FIG. 4, the electric field inside the microwave radiating section 9 is zero on the side of the length b of the core section 9, and on the side of the length a, it is a sine which increases as it goes toward the center. Since the distribution is functional, it is strongest on the center line of the side of length a.

Therefore, the thermosetting adhesive 7, which is the heating target of the wooden cabinet 5, is placed as close as possible to the nine recesses of the microwave radiating section 9, so that it can effectively dielectric in the strongest electric field. heated. On the other hand, the electric field received by the wooden cabinet component 6, which causes wasted microwave power, is weak because it has a sinusoidal electric field distribution, and furthermore, its area is small, so the microwave power wasted by the wooden cabinet component 6 is weak. It can be made small and the temperature rise of the wooden cabinet components 6 is extremely small. The wooden cabinet 5 that has been completely bonded is transported by the transport conveyor 12, and sent to the transport conveyor 13 through the transport door 15 to proceed to the next process.

The above is one cycle of the process of bonding the wooden cabinet 5 according to the present invention, and by repeating the process, continuous heat bonding can be achieved.

As a result of introducing the microwave heating device according to the present invention into a wooden cabinet production line, the time used for microwave heating in one cycle of the wooden cabinet bonding process was 10 minutes.
The multi-process time has been drastically reduced to just seconds. In addition, the adhesive is a thermosetting vinyl acetate emulsion, and the microwave radiator 8 is a microwave output 5 using household microwave oven parts.
00 (W), put 1 on the ridgeline of the wooden cabinet 5.
Two units were installed.

Incidentally, in the above embodiment, the notched groove has a right-angled isosceles triangular shape, but other shapes may be used, and the shape is not particularly limited as long as it forms four parts.

Further, although the object to be heated has been described using a wooden cabinet as an example, it is also possible to apply the invention to furniture, etc., and it goes without saying that it can also be applied to products made of dielectric materials such as synthetic resins instead of wooden products.

As explained above, according to the present invention, since the predetermined part of the object to be heated is intensively heated and partially bonded, the waste of microwave power can be suppressed and the power saving effect can be achieved. At the same time, the process time is shortened and the thermal deformation of the parts during bonding can be reduced, so that the residual stress after bonding can be reduced and the strength of the product can be prevented from decreasing.

[Brief explanation of drawings]

FIG. 1 is a front view schematically showing a conventional microwave heating device, FIG. 2 is a front view showing the internal structure of a microwave heating device according to the present invention, and FIG. 3 is a partially enlarged perspective view of the same device. FIG. 4 is a diagram showing the electric field distribution inside the waveguide in the same device as above, where (A) is a front view and (B) is a bottom view. 5... Wooden cabinet, 8... Microwave radiator, 12... Conveyor, 16... Radio wave shield.

Claims (5)

[Claims] (1) A radio wave shielding chamber that accommodates a heated object freely in and out, a heated object support device that supports the heated object at a predetermined position within the chamber, and a predetermined portion of the heated object provided in the radio wave shielding chamber. Microwave heating characterized by comprising: a microwave radiating device that emits microwaves; and an actuating device that operates the microwave radiating section of the radiating device so as to face a predetermined portion of the object to be heated. Device. (2) The microwave heating device according to claim 1, wherein the object to be heated is taken in and out of the radio wave shielding chamber by a carry-in/take-out device. (3) The microwave heating device according to claim 1 or 2, wherein the microwave radiating device has a radiating section formed of a rectangular waveguide. (4) The rectangular waveguide has a configuration in which the edge of the tip opening is cut out to form a concave portion on the tube tip opening surface.
Microwave heating device as described in section. (5) The object to be heated is any one of claims 1 to 4, in which the part to which the thermosetting adhesive is applied on the joint surface is a predetermined part heated by microwaves. Microwave heating device as described. (61) The microwave heating device according to claim 5, wherein the thermosetting adhesive is a thermosetting vinyl acetate emulsion.