JPS59298A - Manufacture of loudspeaker diaphragm - Google Patents

Abstract

PURPOSE:To execute easily working of a titled diaphragm, and also to obtain a uniform product, by using a forming die which is sufficiently larger than thickness of a plastic film formed by a clearance between plugs gnawed to each other in upper and lower forming dies. CONSTITUTION:Each clearance of a plate-like plug 11a of a upper die 11 and a plate-like plug 11'a of a lower die 11' is set sufficiently larger than thickness of a plastic film 2. When the heated plastic film 2 is placed between the die 11 and the die 11' and is pressed by use of said forming die, a core of the plastic film is obtained. According to such a forming method, first the tip of each plate- like plug of the upper die and the lower die contacts with the heated plastic film and takes away its heat, therefore, the this part is cooled and cured quickly, subsequently an uncooled plastic film between each plate-like plug is stretched and formed, therefore, uneven thickness is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a speaker diaphragm having a circular sandwich structure.

Recently, a sandwich-structured speaker diaphragm has been developed in which skin materials are bonded to both sides of a lightweight and highly rigid core material. A speaker diaphragm having such a structure has a feature of extremely high bending rigidity compared to a conventional cone-shaped speaker diaphragm formed from a single sheet. Therefore, the divided resonant frequency of the diaphragm becomes high, and the reproduction band can be extended. An aluminum honeycomb structure is generally used as the core material of this sandwich structure. However, aluminum honeycomb structures have the disadvantage of high costs because they require many manufacturing steps.

As an alternative to this aluminum honeycomb core, a corrugated core material 2 as shown in FIG. 1, which is obtained by press-forming or vacuum-forming a plastic film, has been proposed. This core material can be manufactured by one molding process, which can greatly reduce the number of steps, but it also has the following drawbacks.

FIG. 2 is a cross-sectional view of a press die for molding the core material 2 shown in FIG. 1, where 1 is an upper die and 1' is a lower die.

In the radial core 2 shown in FIG. 1, the pitch Pl of the ridges in the circumferential direction at the outermost periphery is larger than the pitch P2 of the ridges in the circumferential direction at the inner periphery, so that the side surfaces 2a of the ridges have a twisted shape.

Therefore, it is very difficult to process a press mold for press-molding the core material shown in FIG. Also, upper mold 1 and lower mold 1'
The accuracy of the clearance must be smaller than the film thickness throughout the mold. For these reasons, the cost of the press mold is high. Further, the thickness 2b of the core material, which is related to the bending rigidity of the diaphragm, is determined by the mold, and there is also the drawback that the thickness 2b cannot be freely controlled.

3 and 4 are diagrams showing the principle of vacuum forming the core material 2 shown in FIG. 1. 3 is a vacuum molding mold, 4 is a concave portion of the mold 3, and 5 is a suction hole. In this vacuum forming method, the heated glass film 2 is placed on a mold 3 and the air in the recess 4 is exhausted from the suction hole 5, thereby forming the film as shown in FIG. In this method, the heated plastic film 2 comes into contact with the mold 38 at the start of suction, and the film at that part is removed from heat and hardens immediately, so the thickness of the film is almost the same as before molding. do not have. As the suction is continued, the film begins to deform along the concave portions 4 of the mold, and the film gradually comes into contact with the mold from the portions closer to the mold 3a and hardens. Therefore, the bottom 3 of the recess
The wall thickness becomes thinner as it approaches b, and the wall thickness of the part that contacts the bottom 3b is the thinnest.

As described above, in the vacuum forming method, deviation in film thickness occurs, and the side surface portion 2a, which needs to be thickened, becomes thinner. Therefore, in order to make the thickness of the side surface portion 2a a predetermined value, the molded film must be made considerably thick, which has the drawback of increasing the weight of the entire diaphragm. Furthermore, if the thickness 2b of the core material is increased, the thickness of the film that contacts the bottom 3b of the four parts becomes extremely thin, which may cause the film to tear or break.
It has the disadvantage of being difficult to release from the mold.

The object of the present invention is to eliminate the drawbacks of the above-mentioned molding method and to obtain a core material having a predetermined thickness. Embodiments of the present invention will be described below with reference to the drawings.

5 and 6 are principle diagrams showing a first embodiment of the method of forming the core material shown in FIG. 1 according to the present invention.

11 is the upper mold, 11a is the plate-shaped plug of the upper mold, 11' is the lower mold, ll'a is the plate-shaped plug of the lower mold, and the distance between 11a and 11'a is the thickness of the film 2. Big enough. Using this mold, as shown in FIG.
Sandwich heated plastic film 2 between 1' and
When pressed, a core of the glass film shown in FIG. 6 is obtained. Figure 7.

FIG. 8 is a plan view of the mold shown in FIG. 5, with a plate-shaped plug 11a,
ll'a radiates out from the center.

FIG. 9 shows a second embodiment of the present invention, in which plate-shaped plugs 12a and 12'a'e are constructed in a mold 12° 12' so that the cross-sectional shape in the circumferential direction of the core material is trapezoidal. .

FIG. 10 shows a third embodiment according to the present invention, in which molds 13, 1
The tips of the plate-shaped plugs 13a and 13'a of 3' are rounded to make the cross-sectional shape of the core material in the circumferential direction sinusoidal.

Further, as shown in FIG. 11, a plate-shaped flag 14a,
If the mold 14'a has a rectangular shape in the radial direction, a core material with parallel front and back surfaces can be obtained.Furthermore, the plate plug 15a of the upper mold 15 can be tapered as shown in FIG. By forming a section, it is possible to obtain a core material with a chi and e on the back side.

In addition, the above 1. Second. Plate plug 11 of the third embodiment
'a+11'a, 12a+12'a, 13a+13''a
Of course, the cross section may be tapered.

By adhering skin materials with a high modulus of longitudinal elasticity to the front and back sides of the core material obtained in the above example, 1. A speaker diaphragm with a highly rigid sandwich structure is obtained.

According to the core material molding method according to the present invention described above, first, the tips of the plate-shaped plugs of the upper mold and the lower mold contact the heated Zolast and Kufirum, respectively, and remove heat, so that these parts rapidly The uncooled plastic film between each plate-shaped plug is then stretched and formed. Therefore, in the molding method according to the present invention, it is possible to obtain a uniform thickness without the thickness unevenness that occurs in vacuum molding, and it is possible to eliminate the unevenness of the core material.

In addition, in the mold according to the molding method of the present invention, the plugs of the upper mold and the lower mold can be made into plate shapes, so unlike the mold shown in FIG. It can be manufactured at low cost.

Furthermore, since there are few surface contact areas between the molded product and the mold, the molded product can be easily released from the mold.

Furthermore, in conventional molds, it was impossible to change the thickness of the core material, which is related to the rigidity of the diaphragm, but in the present invention, the upper mold shown in FIGS. 6, 9, and 10.

Dimension 2c that each plate-shaped plug of the lower mold overlaps with each other
Since the thickness can be easily changed by changing the type, core materials of various thicknesses can be produced with one mold, and the optimal sandwich core can be determined in a short period of time at the lowest cost. I can do it.

[Brief explanation of drawings]

Fig. 1 is a partial perspective view of a corrugated core material, and Fig. 2 is a partial perspective view of a corrugated core material.
FIG. 3 is a sectional view showing a conventional press mold. Fig. 4 is a principle diagram of vacuum forming, Figs. 5 and 6 are sectional views showing one embodiment of the present invention, and Figs. 7 and 8 are upper and lower molds used in the same embodiment. , FIG. 9 is a cross-sectional view showing another embodiment of the present invention, FIG. 10 is a cross-sectional view showing still another embodiment of the present invention, and FIGS. 11 and 12 are respective molds. It is a figure showing the radial cross section of. 2...Plastic film (and molded core material), 11, 12.13, 14.15 ・Upper mold, 1'l
', l 2', 13', 14', l 5'-・
・Lower mold, lla. 12a, 13a, 14a, 15a...-upper type plug,
11'a, 12'a, 13'a, 14'a
, 15', a...Lower mold plug. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5. Figure 6 Figure 7 ' Figure 8 Figure 9 Figure 11

Claims (1)

[Claims] In a method for manufacturing a speaker diaphragm in which skin materials are bonded to both sides of a core material made of corrugated plastic film, the clearance between the plugs that engage with each other in the upper and lower molds depends on the thickness of the plastic film to be molded. A method of manufacturing a speaker diaphragm, which is characterized by using a mold that is sufficiently large compared to the size of the mold, and inserting a heated plastic film between the upper and lower molds for press molding.