US2908960A - Sagger pin - Google Patents

Description

United States Patent 2,90 9 J sAGoER- N Edward Schramm, .assig nor to. Onondaga Pottery Company, Syracuse, N.Y., a corporation of New York H Application February 1 9 57, Serial 641,525 3 Claims. (c1. 2s 115s).

are fired at an elevated temperature to produce vi-trous ware.

After the articles have been fired, they are dipped into a glaze solution and are placed in boxes formed of refractory material and known as saggers. In order to support articles of flatware which have been so coated with the glaze material, the articles are supported on the ends of pins mounted in the inner surface of the sagger wall. These sagger pins are conventionally triangular in cross section and are positioned so that one apex of the triangular formation engages the under side of the dish or plate, the pins serving to effectively support the articles while they are fired the second time to fuse the glaze material over the surface of the ware.

It is an object of this invention to provide a new and improved sagger pin which will prevent the problem of chipping in connection with the firing of articles of glazed ware.

Prior to this time, when flatware, or dishes, or the like, was prepared to be fired, the ware was dipped into the glaze and then placed in'a sagger wherein each piece of the ware was supported at three points upon sagger pins.

'The sagger was then closed and put into the kiln to fire the glazed ware. During this firing process, the ends of the sagger pins fused to the bottom of the ware. After the firing was finished, and while the sagger was cooling, tensile stresses developed at the point of contact between the sagger pin and the ware. (This is due to the fact that the sagger, the ware, and the sagger pins, each have a different expansivity.) These strmses combine to cause the fused sagger pin to chip the ware. That is, a small piece of the fired ware would adhere to the sagger pin at the point of contact during the cooling of the fired sagger, thus leaving a depress-ion in the ware. This depression gives the ware an undesirable appearance and can not be corrected in the piece of fired'ware and therefore, it is considered very undesirable in the process of firing glazed ware.

Up to this time, several elforts have been made to solve this problem of chipping. One of these efforts proceeded along structural lines. This method was to make the pin body weaker so that it would be possible to reach a condition where the pin, rather than the ware, would fail during the cooling, thus causing a portion of the pin to break oif, rather than chipping the ware. This solution proved to be impractical for the reason that such pins would not support the ware unless they were increased in size to a considerable extent and this was impossible since an increase in the size of the pin body wouldl mean a decrease in the amount of ware that could be carried and fired in a sagger.

Another method of attempting to solve the problem ofpin chipping was to control and set up a balance between the expansivity rate of each of the sagger, sagger pin, and ware, in order to eliminate the tensile stresses which caused the chipping. Although this solution at first .seemedpractical, it later proved to be impractical for the reason that it became impossible to maintain this balance over any substantial period of time for the saggers themselves, when used' continuously, would show a decrease in the rate of expansivity, thus upsetting the balance.

With my new and improved sagger pin, the drawbacks of previous attempts have been obviated and it is now possible to practically eliminate the problem of pin chipping.

It is therefore an object of my invention to provide a sagger pin which will not chip the ware when the pin separates from the ware after firing.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

In the drawings- Figure 1 is a cross section of a portion of a sagger with a plurality of plates mounted therein.

Figure 2 is a plan view of an individual sagger pin.

Figure 3 is a cross sectional view taken on the line 33 of Figure 4.

Figure 4 is a cross sectional view taken on the line 4*4 of Figure 3.

Figure 5 is a cross section of the ware and sagger pin immediately after separation.

1 indicates a sagger in which a plurality of glazed plates 2 are mounted for firing. These glazed plates are supported on a plurality of sagger pins 3, shown in Figure 2. Each of the sagger pins is coated, at the end thereof which is to support the glazed plates, with a coating material 5 which entirely surrounds the end of the pin (see Figures 3 and 4). The sagger pins 3 are formed of a suitable ceramic material, and the pins are fired before they are placed in the sagger box to provide sufiicient strength and rigidity to support the plates 2 and prevent them from sagging while they are being fired.

This coating material is of a type which will fracture more easily than the glazed Ware, after the glazed ware has been fired. That is to say, when the sagger pins are separated from the plates 2 after firing and upon cooling, the coating 5 will fracture more easily' than the glazed plate 2 so that, upon cooling, contraction of the pins and the plate, tensile stresses between the pin and the plate 'will cause a potrion of the coating 5 to fracture and adhere to the plate, forming a protuberance, or nipple 6, see Figure 5, on the plate. This protuberance, or nipple, is then conveniently removed by griding it flush with the under side of the piece of ware.

The coating 5 is of refractory material which is relatively porous and which is more frangible than the piece of ware whereby, upon cooling of the loaded sagger after fiiring, any stresses developed between the pin and the piece of ware will result in that portion of the coating contacting the ware severing from the pin. Such coating material may consist of kaolin or zirconium silicate. The coating may be applied by dipping the end portion of an unfired pin body into a heavy slurry of the refractory material and then firing the pin in the usual way to produce a strong pin body having a relatively low absorption with the more porous coating at the end having a higher absorption. Also, previously fired pins may be dipped into the slurry of refractory material and refired at hiscuit temperatures. In both instances, the refractory material becomes bonded to the end of the pin.

' r V 2,908,960 I, I

Due to the fact that the coating is more frangible '7 than the glaze, or the body of the piece of ware, the coating will fracture when stresses are developed between the pin and the piece" of Ware, with the result that afragment of the coating will remain adhered to the under side of the dish,'as distinguished from the conventional situation Where a fragment or chip is pulled out of the piece of ware, due to the fact that the fused end of the pin body is less frangible than the piece of ware.

The coating 5 permitsthe pin body to be made as dense as desired for strength and need not be increased in cross sectional area. Likewise, the control of expansivity of the pins and saggers becomes of little or no importance. Further, the use of such a coating will minimize the size of the protuberance, or nipple, adhered to 15 ware during the firing of the ware, said pin comprising an elongated body formed at the end supporting the ware with a coating of refractory'mater-ial bonded to the body of the pin, said refractory material being more frangible than the Ware and the pin body whereby, upon cooling of the ware, that portion of the coating contacting the Ware Will sever from the pin.

'2. A sagger pin as set forth'in claim 1, wherein said coating is formed of kaolin.

3..A sagger pin as set forth in claim 1, wherein said coating isformed of zirconium silicate.

References Cited in the file of this patent UNITED STATES PATENTS

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