US1598125A - Process for cleaning tin plate - Google Patents

Description

Aug. 31 ,1926. 1,598,125

. C. FINNEGAN PROCESSFOR CLEANING TI N PLATE Filed Nov. 4, 1925 Patented Aug. 31, 1926.

CHARLES FINNEGAN, 0F GIBSONIA, PENNSYLVANIA.

PROCESS FOR CLEANING TIN PLATE.

Application filed November 4, 1925. Serial No. 66,822.

The invention relates to a process for cleaning tin-plate. In the process of manu facture, tin-plate receives an oil treatment to facilitate the spreading of the tin coating and the removal of any excess immediately after it emerges from the bath. It then be comes necessary to remove the oil, and it has been the practice to accomplish this by carrying the sheets through a bin or compartment supplied with middlings and brushes. The middlings absorb the major portion of the oil, which action is facilitated by the brushes, the final brushes serving to remove the middlings themselves preliminary to the discharge of the plates from the bin. This procedure cleans the plates sufliciently for most purposes, but there still remains a very thin fihn of oil and often some small particles of middlings; and this oil and the particles of middlings which remain are more or less objectionable when the plates are to be decorated or printed, as the quality of the work is materially affected by these materials. If the quantity of oil remaining happens to be excessive, it entirely unfits the plates for printing and decorating and this sometimesr'esults in their rejection by the purchaser. The cleaning with the mid dlings also presents objectionable features, among which is the cost and the difficulty of maintaining the apparatus at a uniform degree of eificiency unless a high degree of care is observed.

The. present invention is designed to provide a process for insuring that the oil is entirely removed from the plates, as well as any particles of the middlings left after the brushing operation. It is further designed, in one of its embodiments, to do away entirely with the necessity of cleaning with the middlings and so avoid the expense and other objections incident to the size of the middlings.

Briefly stated, the desired result is secured by passing the plates slowly through a furnace which removes the oil, apparently by a volatizing or vaporizing action, and drys or carbonizes any middling particles, so that they drop away from the plates or are readily blown away by air blasts as the plates emerge from the furnace. The temperature of the furnace is such that the oil is entirely removed, but is below the point where there is danger of injury to the coating by softening or crystallizing, sometimes referred to as burning. The plates are in this manner entirely freed from any trace of oil. The plates are preferably carried through the furnace in an upright position upon an endless conveyor, so that both sides are exposed to the action of the heat and a free vaporizing of the oil from both surfaces occurs during the movement through the furnace. A temperature ranging from 250 to 400 degrees Fahrenheit is suflicient to secure the desired removal of the oil without danger of injury to the tin coating upon surfaces of the plates, the degree of heat applied depending on the time given for the passage of the plates through the furnace. The plates are deposited upon trucks, as they emerge from the furnace, in packs of size convenient for handling, and because of the absence of any oil films on the surfaces, any tendency of the plates to slide laterally in the pack during handling is avoided, thus rendering the packs easier to move and pack than is the case with plates having slightly oiled surfaces.

Two forms of apparatus for use in carrying out the process are shown in a diagramm'atic way in the accompanying drawings, wherein:

Figure 1 is a partial side elevation and partial section through one form of apparatus in which the middlings cleaning bin is employed. Fig. 2 is a section on the line IIII of Fig. 1. And Fig. 3 is a partial side elevation and partial section through a modified form of apparatus in which the, middlings cleaning device is dispensed with.

Referring first to the showing of Fig. 1, the numeral 1 designates the end of the tank carrying the tinning bath in the end of which is an oil bath through which the tinned plates are passed to facilitate the draining off of any excess tin. The plates are then carried between the pairs of driven rolls 2 to the middlings bin 3. This bin is provided with the usual sets of felt rolls 4, driven at varying speeds to facilitate the rubbing away to bring a maximum quantity of the middlings into contact with the plates. A continuous supply of middlings is passed through the bin from the spout 5, such middlings being removed from the bottom of the bin through the outlet 6 and returned to the hopper 7 by any suitable transfer mechanism, not shown. The outlet end of the bin is provided with the usual driven brush rollers 8 for removing the particles of of the oil upon the plates and middlings adhering thereto. The middlings cleaning unit is a device well known in the art and constitutes no part of the present invention.

The heating or vaporizing furnace 9 is arranged in alignment with the outlet end'of the middlings cleaner. It is of the tunnel type and includes an endless carrier in the form of a pair of chains 10,10, passing around the pairs of sprockets 11, 12 at the ends of the furnace and carried upon the shafts 13 and 14. One of these shafts is provided at its end outside the furnace w1th another sprocket 15 (Fig. 2) driven slowly by suitable operating means not shown, the movement being preferably step-by-step to facilitate the reception of the plates from the brush rollers 8. Extending between the chains, in U-form, are the wires 16 (Fig. 2) which act as supports for holding the plates 17 in upright position as they pass through the furnace, as indicated in Fig. 1. The plates are in this way exposed to the full vaporizing efiect of the heated gases of the furnace, the heat being preferably supplied from the perforated gas burners 18 extending transversely of the furnace adjacent the bottom wall. Any other suitable heating means may be substituted for the gas burners. Air blasts from the vertical perforated headers 18 (supplied from a pump or compressor) serve to remove any particles of middlings which remain adhering to the plates.

In operation, the plates passing through the middlings bin 3 are cleaned from the bulk of the oil thereon and are brushed free from the major portion of the middlings by the brushes 8. The conveyor in the furnace 9'may be given a step-by-step movement timed so as to correspond to the feed of the plates from the bin so that the attention of an operator at this point may be largely dispensed with. The plates are'heated and the oil films dried away or oxidized as the plates pass through the furnace. and upon their exit may be received and stacked upon a truck such as the one 19 of Fig. 1, the truck being removed, when the ack is complete, and another truck moved into position.

Fig. 3 illustrates a modification of the apparatus and process, the middlings bin being omitted in this case, and the plates being carried direct to the furnace 9, which is the same in e uipment as the furnace of Fig. 1, the parts eing similarl numbered. In this case, the pairs of rol s 20 deliver the plates 21 to the brush rolls 22, which remove the bulk. of the oil, preliminary to feeding the plates into the endless conveyor.

Any other suitable means may be used in place of the brushes 22 for scraping off or removing the bulk of the oil. The cleaning effect of these mechanical rubbing or scraping means is not the same as that secured by the middlings bin, but the films of oil must still be removed by the heating action in the furnace.

The invention is not limited to the form of tunnel kiln shown. Various shapes may be used depending on conditions and the space available, which may not permit of a straight-away kiln, such as the one illustrated. The showing of the kiln and other apparatus is diagrammatic throughout, and it will be understood that details such as the number of rolls or brushes and their spacing may be varied in accordance with practical requirements in the art. Also that the usual accessories for handling sheets may be utilized such as suitable automatic means for stacking the plates and squaring up the piles on the trucks. An advantage is involved in feeding the plates directly into the oven without stacking them up before the heat treatment, in that, any particles of foreign material, such as the middlings, adhering to the plates will drop off more readily during such heat treatment, if such particles have not been caused to adhere more firmly by pressure, such as they would be exposed to in stacking.

What I claim is 1. A process for removing the oil coating applied to tin-plate in the process of manufacture which consists in carrying the plates through a chamber exposed to a temperature sufficient to remove the oil, but below a point at which the coating uponthe plates is affected.

2. A process for removing the oil coating applied to tin-plate in the process of manufacture which consists in carryin the plates through a chamber in an uprig t position an dexposed to a temperature such as to remove the oil without affecting the metal coating upon the plates.

3. A process for removing the oil coating applied to tin-plate in the process of manufacture which consists in carrying the plates through a chamber exposed to a temperature suflicient to remove the oil, but below a point at which the coating upon the plates is affected, and applying a blast of air to the plates after the oil is removed.

4. A process for removing the oil coating applied to tin-plate in the process of manufacture which consists in carrying the plates through a chamber in an upright position and exposed to a temperature such as to remove the oil without affecting the metal coating upon the plates and applying .a blast of air across the plates to remove any particles of material adhering thereto.

5. A process for removing the oil coating applied to tin-plate in the process of manufacture which consists in brushing the surfaces of the plates to remove the bulk of the oil and then carrying them through a them, as the move along, shifting the plates chamber exposed to a temperature such as to an uprig t position, and exposing them to dry awa the oil remaining on the plates, 'to a relatively high temperature, as the but not su cient to affect the metal coating are carried ahead to'remove the film of 011 I upon the plates. adhering thereto, but Without crystallizing 1 6. A process for removing the oil coating the tin coating.

applied to tin plate in the process of manu- In testimony whereof, I have hereunto facture, which consists in carrying the plates subscribed my name this 3rd day of N ovemahead in series, exposing the plates to conber, 1925.

I n tact with absorbent material and brushing CHARLES FINNEGAN.

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