JPH0319064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a fritch manufacturing apparatus. [Background Art] In general, a fritsch manufacturing device includes an upper mold having a convex curved surface and a lower mold having a concave curved surface, and between the upper mold and the lower mold, Fritches are manufactured by inserting a laminate in which a plurality of material veneers (wooden veneers, etc.) are laminated with an adhesive and then pressing them together. However, when manufacturing fritches in this way, the curing of the adhesive does not progress easily, so as shown in FIG. A high frequency electrode plate 4 is also placed on the mold surface.
It has been devised to apply high-frequency dielectric heating to the laminated veneer material 5 during pressing, and has already been carried out in some cases. However, when high-frequency dielectric heating is applied in this way, since the high-frequency electrode plates 2 and 4 are curved as shown, the high-frequency electric field 6 has areas where it is dense and areas where it is sparse, and the temperature rises in the areas where the electric field is dense. The temperature rise will be small where the temperature is large and sparse. High-frequency dielectric heating is performed based on the temperature of the high-temperature part in order to prevent deterioration of the material due to high temperatures. Therefore, there has been a problem that poor adhesion occurs in areas where the temperature rise is small. [Object of the Invention] The purpose of the present invention is to eliminate such a temperature difference. [Disclosure of the Invention] The present invention comprises an upper mold having a curved surface that is one of convex or concave, a lower mold having the other curved surface of convex or concave, and the upper mold and A high-frequency electrode plate formed on the mold surface of the lower mold, a cover that is thick in the center and thin at the ends and is attached to the convex high-frequency electrode plate, and a cover that is attached to the convex high-frequency electrode plate, and a concave high-frequency electrode plate. A cover that is attached to the top is thin in the center and thick at the ends, and the target die surface shape is formed by the above mold and the cover attached to the mold surface, and the cover is the object of fritching. The gist of this invention is an apparatus for producing a fritsch characterized by being made of a material having a smaller dielectric constant and dielectric loss tangent than the material laminate of single plates. That is, by adopting the above structure, it is possible to eliminate the temperature difference. Next, this invention will be explained in detail. When high-frequency dielectric heating is performed using a highly curved electrode plate as shown in Figure 1, a high-frequency electric field is generated radially as shown by thin lines 6 in Figure 1, and the electric field intensity distribution becomes non-uniform. . In order to make this electric field intensity distribution uniform, the upper mold 7 should be made flat (second
Figure) A flat electrode plate 8 is attached, and the electrode plate 8 has the same shape as the convex curved part of the upper mold 1 in Figure 1 and the same dielectric material as the material veneer laminate 5 to be pressed. In addition to attaching the curved shape 9 having the characteristics, the lower mold 10 and the electrode plate 11 are configured in the same manner as above, and furthermore, the curved shape 12 having the same dielectric characteristics as the material veneer laminate 5 is attached on the electrode plate 11. , it is possible to apply high-frequency dielectric heating. Usually, the curved shapes 9 and 12 are made of the same material as the material veneer laminate 5. In this way, the portion between the flat upper electrode plate 8 and the lower electrode plate 11 (laminated body 5 and molds 9, 12) will all have the same dielectric properties (usually the same material), and will become parallel flat plates. This is the same as placing a laminate of material veneers between electrodes and subjecting them to high-frequency dielectric heating. Therefore, the high frequency electric field strength distribution becomes uniform as shown by the thin line 6 in FIG. However, in this case, the curved molds 9 and 12 are also heated at the same time as the material veneer laminate 5 is heated, so if this is used repeatedly, the temperature will become extremely high, and the curved molds 9 and 12 will be heated. , 12 deteriorate and deform.
In order to suppress the heat generation of the curved shapes 9 and 12, the heat generation is calculated by the following formula, so P=5/9fεtanδE ² ×10 ^-10 (W/m ³ ) f: Frequency (Hz) ε: Specific dielectric Rate tan δ: Dielectric loss tangent E: Electric field strength (V/m) As the constituent material of the curved shapes 9 and 12, a material with a small relative permittivity ε and a small dielectric loss tangent tan δ may be used. That is, using a material with a small dielectric constant ε and a small dielectric loss tangent tan δ, the curved shapes 9 and 12 and the admittance (Y=G+jωC, G=ωεtanδ(A)/(d), C=ε
The purpose can be achieved by configuring it into an equal type (A)/(d)). However, in reality, the curved shape 9, 12
It is difficult to satisfy the above conditions by constructing the entire device from a single material. Therefore, we used a material with a smaller dielectric constant and dielectric loss tangent than the laminate 5 to make an upper mold cover that is thick in the center and thin at the ends, and a lower mold cover that is thin in the center and thick at the ends. As shown in the figure, an upper mold cover 16 is attached to the upper mold 14 whose convex portion has a small degree of curvature through an electrode plate 15, and an electrode plate 18 is attached to the lower mold 17 whose concave portion has a small degree of curvature. The above conditions can be easily met by attaching the lower die cover 19 and applying high frequency dielectric heating. Here, upper mold 14, lower mold 1
The degree of curvature of No. 7 is set so that the shape of the mold surface after being covered with the covers 16 and 19 becomes the desired shape of the mold surface. Next, specifically, the upper mold cover 16 and the lower mold cover 16,
19 shape and the upper mold 14 to which it is attached,
Setting the mold surface shape of the lower mold 17 will be explained with reference to FIG. 4. (Step 1) In Fig. 4, the conditions for making the electric field intensity distribution uniform are that there is no potential difference in the lateral direction (y constant), and V ₁ = Vy ₁ /d...(1) V ₂ = Vy ₂ /d...(2) becomes. (Step 2) Cover 1 to satisfy the conditions of equations (1) and (2) above.
6. Determine the thickness of 19. When the Γ shape is a sin type (symmetrical type) y ₁ = A (1-sinx/2lπ) ...(3) y ₂ = Asinx/2lπ ...(4) In addition, the covers 16 and 19 and the laminated veneer of the material The admittance Y of the body is expressed as follows. Y=G+jωC=(σ+jωε)ΔS/d...(5) Y ₁ =(σ ₁ +jωε ₁ )ΔS/d ₁ ...(6) Y ₂ =(σ ₂ +jωε ₂ )ΔS/d ₂ ...(7 ) Here, since the amount of current flowing is constant, VY=V ₁ Y ₁ = V ₂ Y ₂ ...(8) Substituting equations (5) and (6) into equation (8), we get V/V ₁ = Y ₁ /Y=σ ₁ +jωε ₁ /σ+jωε・
d/d ₁ =σ ₁ σ+ω ² ε ₁ ε+jω(σε ₁ −σ ₁ ε)/σ ²
+ω ² ε ²・d ₂ /d ₁ ...(9) From (1) and (9) d/y ₁ = |V/V ₁ |=√(σ ₁ σ+ω ² ε
₁ ε) ² +ω ² (σε ₁ −σ ₁ ε) ² /σ ² +ω ² ε ²・d/d ₁ d ₁ =√(σ ₁ σ+ω ² ε ₁ ε) ² +ω ² (σ
ε ₁ −σ ₁ ε) ² /σ ² +ω ² ε ²・_y 1Similarly, d ₂ =√(σ ₂ σ+ω ² ε ₂ ε) ² +ω ² (σ
ε ₂ −σ ₂ ε) ² /σ ² +ω ² ε ²・y ₂ (Step 3) Next, cover 1 obtained as above
Based on the values of 6 and 19, the degree of curvature of the upper mold 14 and the lower mold 17 is determined so that the mold surface shape after being covered with the covers 16 and 19 becomes the target sin shape. This degree of curvature is obtained by drawing a circle having a thickness d ₁ of the cover 16 or 19 at that point from a certain point of the Sin type, and connecting the tangents of these circles with the adjacent circles. (x-a) ² + (y-b) ² = r ² (x ₁ ,
The equation of the tangent at the y ₁ ) coordinate is (x ₁ -a) (x-a) + (y ₁ -b) (y-b
)=r ² x=a+r ² (x ₁ −a)±r(y ₁ −b)√(x ₁
-a) ² + (y ₁ - b) ² -r ² / (x ₁ - a) ² + (y ₁ - b) ^{2
y=b+r 2 (y ₁ −b) 〓r(x ₁ −a)√(x ₁
-a) 2 + (y ₁ - b) 2 -r 2 / (x ₁ - a) 2 + (y ₁ - b) 2
becomes. A 3/5 scale diagram of the Sin type actually obtained in this way is shown in Figure 5. In this case, the material veneer (Agathis veneer) laminate has ε = 17.3 and tan δ = 1.12,
The covers 16 and 19 are made of polyester, and ε=
3.60, tan δ = 0.03. Note that 14 is an upper mold, and 17 is a lower mold. Next, a specific example of flitch manufacturing will be explained. A flitch was manufactured using the flitch manufacturing apparatus shown in FIG. 3 in the following manner. That is, agathis destained veneer with a moisture content of 20-40% (ε = 15.5,
A fritchi was manufactured by laminating 100 sheets of polyester sheet (tan δ = 1.25) and performing high-frequency dielectric heating molding using a polyester sheet (ε = 3.6, tan δ = 0.03) as a cover. At this time, a mold with a sinusoidal half-wavelength shape and an end angle of 26.6° was used. Additionally, the maximum thickness of the cover was set to 8.4mm. Regarding the temperature rise caused by high-frequency dielectric heating, when heating the whole body from room temperature to 70℃ using the conventional method without using a cover, the temperature variation was about ±20℃, but by using a cover, the temperature variation was ±8℃. ℃ or less, and we were able to eliminate the partial adhesion failure caused by temperature variations. [Effects of the Invention] As described above, the fritch manufacturing apparatus of the present invention has an upper mold having a curved surface that is either convex or concave, and a curved surface that is the other curved surface that is convex or concave. A lower mold with a surface, a high-frequency electrode plate formed on the mold surfaces of the upper mold and lower mold, respectively, and a cover that is thick in the center and thin at the ends, which is attached to the high-frequency electrode plate of the convex mold. and a cover that is thin in the center and thick at the ends, which is attached to the high-frequency electrode plate of the concave mold, and the target mold surface shape is formed by the above mold and the cover attached to the mold surface. and the cover is made of a material that has a smaller relative dielectric constant and dielectric loss tangent than the material laminate of single plates to be fritched.
It becomes possible to eliminate temperature variations in the laminate of veneers of material during high-frequency dielectric heating. Therefore, occurrence of partial adhesion failure due to frizz can be prevented.}

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional example, Fig. 2 is an explanatory diagram of the principle of the present invention, Fig. 3 is an explanatory diagram of an embodiment of the present invention, Fig. 4 is an explanatory diagram of the design of the cover shape and mold surface shape, FIG. 5 is an explanatory diagram of a specific example designed accordingly. 14... Upper mold, 15, 18... Electrode plate, 16...
...Upper die cover, 17...Lower die, 19...Lower die cover.

Claims (1)

[Claims] 1. An upper mold with a curved surface of one of convex or concave shapes, a lower mold with a curved surface of the other of convex or concave shapes, and molds on the mold surfaces of the upper mold and the lower mold, respectively. A high-frequency electrode plate to be formed, a cover that is thick at the center and thin at the ends to be attached to the convex-shaped high-frequency electrode plate, and a center part to be attached to the concave-shaped high-frequency electrode plate. The mold has a cover that is thin and thick at the ends, the target mold surface shape is formed by the above mold and a cover attached to the mold surface, and the cover is made of a laminate of material veneer that is to be fritched. A manufacturing device for a fritsch, characterized in that it is made of a material having a small dielectric constant and a small dielectric loss tangent.