Hard Chrome Plated Vibrating Board Of An Ultrasonic-wave Washer

Abstract

A vibrating board for an ultrasonic-wave washer fitted to an opening formed in the bottom of a washing tank to form a vibrating bottom of said tank with a plurality of tremblers fixed thereto at its under surface of the board which contacts a washing liquid in said tank is plated with a hard chrome. Moreover, at least four corners of the vibrating board are formed thinner than the substantial central area of the board to which the tremblers are attached from the below. Such construction of the vibrating board can avoid an erosion on the board, eliminated a breakdown of the tremblers and ensure a reliable transmission of an ultrasonic-wave to the liquid, and thus prolongs the durable years of the vibrating board.

Description

This invention relates to a vibrating board for an ultrasonic-wave washer, and more particularly to an improvement in a vibrating board attached to the bottom of a washing tank of the ultrasonic-wave washer especially usable for dish washing.

In such an ultrasonic-wave washer, an ultrasonic-wave is applied to a washing liquid in the tank through vibration of a vibrating board made of a stainless steel etc. to which a plurality of tremblers are attached from the back. In a conventional ultrasonic-wave washer of the type, an erosion which occurs on the vibrating board accompanying a strong ultrasonic-wave generated in the liquid can be hardly prevented at the present technical level in this field. The erosion has a tendency to give a larger damage to the board, the stronger the vibration is.

Usually, the vibrating board is made of a 18-8 stainless steel for avoiding an erosion which, however, has sometimes a trouble of breaking the tremblers during operation due to a difference in coefficients of thermal expansion between said 18-8 stainless steel and a ferrite forming the tremblers. Heretofore, in order to solve the problem, a double coating of an aluminum plate over the under surface of the board or other measures have been adopted. It is most preferable to employ a titanium for the double coating, which, however, is extremely expensive.

In analysis, the erosion on the vibrating board is found to be a kind of evaporation of metals. When a metal hard to evaporate is applied to the surface contacting the liquid, the advance of the erosion can be checked to a considerable extent. Further, if the contact face is uniformly made as smoothly as a mirror-face, adhesion of foams to the contact face can be eliminated and a favorable contact with the liquid assuring a good transmission of the ultrasonic-wave can be obtained.

For further overcoming the erosion, there is an idea that the vibrating board should be thick enough to withstand the erosion. In this case, however, the thicker the board is, the more deterioration of the ultrasonic-wave is observed. The stainless steel employed for the vibrating board has a large flexural rigidity in its property which makes it impossible to transmit a reliable vibration to the washing liquid when the vibrating board is made thick enough to prevent the erosion. On the other hand, when the board is made thinner, the vibrating board easily yields to erosion.

It is, therefore, an object of the present invention to provide a vibrating board for an ultrasonic-wave washer which is superior in its erosion resisting property and free from damages in tremblers, since the vibrating board has little difference in a coefficient of thermal expansion from the tremblers made of a ferrite.

It is another object of the present invention to provide a vibrating board for an ultrasonic-wave washer which can transmit a vibration of the vibrating board uniformly and effectively to a washing liquid and overcome a flexural rigidity of the board, even though employing a thick material enough to withstand the erosion.

Essentially according to the present invention, there is provided a vibrating board for an ultrasonic-wave washer fitted to an opening formed in the bottom of a washing tank and comprising a table portion protruding in said tank and carrying a plurality of tremblers thereunder, a surface of said table portion contacting a washing liquid in said tank being plated with a hard chrome; and a flange portion integrally formed with said table portion and fixed to the bottom of the tank.

Various, further, specific objects, features and advantages of this invention will be described by way of example with reference to the accompanying drawings illustrating a preferred embodiment of this invention, in which;

FIG. 1 is a longitudinal sectional view of a washing tank of an ultrasonic-wave washer provided with a vibrating board according to this invention;

FIG. 2 is a sectional view of the vibrating board;

FIG. 3 is a perspective view of a vibrating board having all the four corners of a table and a flange portion thereof planed thinner; and

FIG. 4 is a sectional view taken on a line IV--IV of FIG. 3.

Referring now to FIG. 1, a washing tank 1 has a large opening 1b in its bottom 1a. A vibrating board 2 of 18-8 stainless steel is attached to the washing tank from outside in such a manner that a table portion 2a of the vibrating board 2 protrudes in said tank 1 through said opening 1b. Said vibrating board 2 is fixed to the bottom 1a of the washing tank 1 by way of its flange portion 2b, through a packing member 3 provided therebetween, with bolts and nuts 4.

Tremblers 5 are fixed to the under surface of the table portion 2a of the vibrating board 2.

As shown in FIG. 2, the vibrating board 2 consists of a base plate 21 of 18-8 stainless steel and a plated layer 22 of a hard chrome in the thickness of 20 - 30 .mu..

Further in order to overcome a trouble of erosion, the vibrating board may preferably be made of a thick material. However, as stated hereinbefore, the stainless steel employed for the vibrating board has a large flexural rigidity in its property which makes it impossible to transmit a reliable vibration to the washing liquid, when the material is made rather thick. This problem can be settled by making at least the four corners of the table portion 2a and the flange portion 2b thinner than the central area of the table portion as illustrated in FIGS. 3 and 4. In this case, the four corners of the table 2a and the flange portion 2b of the vibrating board 2 are planed thinner prior to pressing so as to be about one-fourth thinner than the central area of the table portion 2a which is thick enough to withstand erosion. The thickness of the thicker central area of the table portion 2a is preferably 1.2 - 1.6 mm though it varies depending on the capacity of the washer and the number of the tremblers. Alternatively, the entire circumference of the table portion 2a except the central area and the entire flange portion 2b may be formed thinner.

After planing is completed, a step is made in the vibrating board 2 to form the table portion 2a and the flange portion 2b in the process of pressing.

The present vibrating board with at least the four corners of the table portion and the flange portion thereof planed thinner than the central area of the table portion 2a to which the tremblers 5 are attached can offer a powerful sound field in the liquid in the washing tank and, at the same time, can eliminate a breakdown by erosion, since the substantial portion of the board is formed thick. If two washing tanks having the same capacity but provided with different vibrating board, namely, the conventional one and the present one are operated employing the same ultrasonic-wave oscillator, the present vibrating board can produce far stronger sound field than the conventional board. Therefore, in order to produce a determined sound field, the output power of the oscillator can be smaller in combination with the present vibrating board advantageously from the economical point of view.

As set forth hereinabove, the vibrating board for an ultrasonic-wave washer according to this invention has various advantages that the plating of a hard chrome over the surface thereof can highly elevate an erosion resisting property of 18-8 stainless steel and eliminate damages in tremblers since a stainless steel plated with a hard chrome has little difference in a coefficient of thermal expansion from the tremblers made of a ferrite. Moreover, the surface of the vibrating board is formed so smoothly with a hard chrome plating that a favorable transmission of the ultrasonic-wave can be assured.

Further advantages of the present invention are that the thicker substantial area of the vibrating board can fully avoid an erosion on the board, thus prolonging its span of life and that, notwithstanding, the present vibrating board can offer a powerful sound field in the tank with its thinner circumferential area.

Claims

What is claimed is:

1. A vibrating board for an ultrasonic-wave washer fitted to an opening formed in the bottom of a washing tank and comprising a table portion protruding in said tank and carrying a plurality of tremblers thereunder, a surface of said table portion contacting a washing liquid in said tank being plated with a hard chrome; and a flange portion integrally formed with said table portion and fixed to the bottom of the tank.

2. A vibrating board for a ultrasonic-wave washer as claimed in claim 1, wherein the thickness of the finished plating layer of the hard chrome is about 20 - 30 .mu..

3. A vibrating board for an ultrasonic-wave washer as claimed in claim 1, wherein at least four corners of the table portion and the flange portion are formed thinner than a central area of the table portion carrying the tremblers thereunder.

4. A vibrating board for an ultrasonic-washer as claimed in claim 3, wherein the thickness of the thinner area is about three-fourth of that of the thicker area.