METHOD FOR QUENCH SEASONING OF IRON/STEEL COOKWARE

Abstract

The method for quench seasoning multiple units of iron/steel cookware includes the steps of: preheating each cookware unit to a temperature above the smoke point of oil in an oil bath; rapidly plunging the preheated cookware units into the oil bath to completely submerge the cookware units and quickly enough to ensure the temperature of the cookware units remain above oil smoke point; controlling the temperature of the oil bath to a ensure that the temperature of the oil bath does not reach a temperature close to oil smoke point, for example, a temperature within 20 degrees below smoke point, and retrieving the cookware units from the oil bath.

Claims

1. A method for quench seasoning multiple units of iron/steel cookware comprising the steps of: preheating each cookware unit to a temperature above the smoke point of oil in an oil bath; rapidly plunging the preheated cookware units into an oil bath to completely submerge the units and quickly enough to ensure the temperature of the cookware units remain above oil smoke point; controlling the temperature of the oil bath to a ensure that the temperature of the oil bath does not reach a temperature too close to oil smoke point; and retrieving the cookware units from the oil bath.

2. The method of claim 1 wherein the step of preheating the cookware units comprises the steps of: heating an oven; placing the cookware units on a conveyor belt; and moving the cookware units on the conveyor belt through the oven such that the cookware units are heated to a temperature above the smoke point of oil in an oil bath.

3. The method of claim 2 wherein the step of rapidly plunging the preheated cookware units into an oil bath comprises providing a chute extending from the oven to the oil bath such that the cookware units move from the oven to the oil bath.

4. The method of claim 1 further comprising the step of draining excess oil back into the oil after the cookware units are removed from the oil bath.

5. The method of claim 1 further comprising the step of draining excess oil by placing the cookware units exiting from the oil bath on a conveyor situated over the oil bath.

6. The method of claim 1 wherein the step of retrieving the cookware units from the oil bath comprises providing a partially submerged conveyor to move the cookware units out of the oil bath.

7. The method of claim 1 wherein the step of controlling the temperature of the oil bath comprises the step of cooling the oil in the oil bath to a temperature to ensure that the oil bath doesn't reach a temperature within 20 degrees below smoke point.

8. The method of claim 1 wherein the step of controlling the temperature of the oil bath comprises the step of continuously cooling the oil in the oil bath.

9. The method of claim 1 further comprising the step of adding texture to the surface of the cookware units prior to preheating the cookware units.

10. The method of claim 9 wherein the step of adding texture comprises grit blasting or peening.

11. The method of claim 1 wherein the cookware unit is preheated to a temperature higher enough to fully transform the oil into a gray/black hard polymerized seasoning but low enough to avoid the seasoning being burned and flake off the cookware by the excessive heat.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS

[0015] The present invention relates to a method for quench seasoning of iron/steel cookware as described in detail in the following specification and recited in the annexed claims, taken together with the accompanying drawings in which:

[0016] FIG. 1 is an illustration of an example of the equipment which could be used to perform the method of the present invention; and

[0017] FIG. 2 is a flow chart of the steps of the method.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention provides a method of quench seasoning iron/steel cookware such as pans suitable for commercial production which employs automation with minimal human contact. The method may be performed using the equipment shown in FIG. 1, including:

[0019] An automated conveyor system, generally designated A, for moving the cookware units. The conveyor system A, for example, could be an overhead conveyor track with hooks, or surface conveyors such as rolling metal mesh belt 10.

[0020] A suitable oven, generally designated B, including an open-ended heat chamber for conveyor A to pass the cookware units through for a sufficient time to preheat the cookware units to a temperature above the smoke point of oil, but below the disintegration point.

[0021] A container, generally designated C, for oil bath, which allows the cookware units to be rapidly plunged into the oil bath to be entirely submerged and fast enough to ensure the temperature of the cookware units remain above the oil smoke point, while minimizing splash and smoke generated. This causes the cookware to be quickly transformed into the hard, seasoned product when the hot cookware unit is very rapidly cooled below the smoke point.

[0022] The cookware unit is preheated to a temperature higher enough to fully transform the oil into a gray/black hard polymerized seasoning but low enough to avoid the seasoning being burned and flake off the cookware by the excessive heat. Plunging could be simply a drop into the oil bath, or more controlled short steep chute 12 which delivers the cookware units to the oil bath in the correct orientation and a second conveyor 14 which moves the cookware units from chute 12 through the oil bath.

[0023] Preferably, a temperature control system, general designated D, which acts as a means of continuously cooling the oil bath to ensure that the oil bath doesn't reach a temperature too close to the oil smoke point, for example, within 20 degrees below smoke point, to avoid excessive emissions, or danger of flash fire.

[0024] Preferably, an automated method of retrieving the cookware units from the oil bath, such as partially submerged conveyor 14 or hook system to transport the cookware units to a draining area which preferably recycles the remaining wet oil back into the bath, such as a third conveyor 16.

[0025] In trials, improved results were found when the cookware was grit blasted/peened before entering the quench seasoning process. The added texture helped the oil grip to the surface of the iron/steel better than a smooth wrought, polished, or machined surface finish.

[0026] Instead of conveyors, a racking system could be used to transport cookware units into and out of oven, then into oil bath, although plunging multiple cookware units simultaneously into the oil bath would be problematic (speed of plunge and heating of the oil bath) and throughput would be limited by the volume of oil required around each cookware unit to avoid these undesirable effects.

[0027] An overhead conveyor and hook system could be used throughout, although the plunge into the oil bath would need to be more rapid than most conveyor systems would allow.

[0028] A tilting oven, which discharges all the cookware units into an oil bath when tilted after heating could be used. However, practical problems in using such an oven include too little oil volume around each pan for correct cooling, and impact damage from colliding pans.

[0029] Different types of oil have different smoke points and therefore will necessitate a different temperature for the cookware units immediately before the plunge in the oil (the quench). One example is rice bran oil, which typically requires a temperature of 450 C-480 C (depending on the exact rice bran oil used). Any lower, and the oil may not fully transform into a gray/black hard polymerized seasoning. Any higher, and the seasoning may be burned and flaked off the pan by the excessive heat. Several trials at different temperatures may be necessary to arrive at the optimal temperature for each particular oil.

[0030] Quench time should be the same for all oils: rapid enough to avoid the cookware units dropping below the optimal temperature range for the oil, as described above, before it plunges into contact with the oil. A very slow plunge would cool the cookware units below the transformation temperature of the oil ahead of its contact with the oil, resulting in lighter coloring and sticky semi-transformed oil.

[0031] In practice, the whole cookware unit should be fully immersed in the oil bath within one second, for most common thicknesses of iron or steel cookware. A thicker cookware unit can be plunged slightly more slowly, due to greater internal heat retention, while a thinner pan would need a faster plunge to avoid losing temperature too quickly.

[0032] Further, it is advantageous to add texture to the surface of the cookware units prior to preheating the cookware units. This can be achieved by grit blasting or by peening, which is the process of working a metal's surface to improve its material properties, usually by mechanical means, such as hammer blows, by blasting with shot or blasts of light beams.

[0033] Accordingly, the present invention is a method for quench seasoning multiple units of iron/steel cookware comprising the steps of:

[0034] preheating each cookware unit to a temperature above the smoke point of oil in an oil bath;

[0035] rapidly plunging the preheated cookware units into an oil bath quickly enough to ensure the temperature of the cookware units remain above oil smoke point;

[0036] controlling the temperature of the oil bath to a temperature ensure that the temperature of the oil bath does not reach a temperature too close to oil smoke point; and

[0037] retrieving the cookware units from the oil bath.

[0038] The step of preheating the cookware units includes the steps of:

[0039] heating an oven;

[0040] placing the cookware units on a conveyor belt; and

[0041] moving the cookware units on the conveyor belt through the oven such that the cookware units are heated to a temperature above the smoke point of oil in an oil bath.

[0042] The step of preheating the cookware comprises preheating the cookware unit to a temperature higher enough to fully transform the oil into a gray/black hard polymerized seasoning but low enough to avoid the seasoning being burned and flake off the cookware by the excessive heat.

[0043] The step of rapidly plunging the preheated cookware units into an oil bath includes providing a chute extending from the oven to the oil bath such that the cookware units move from the oven to the oil bath and are fully submerged in the oil bath.

[0044] The method further includes the step of draining excess oil back into the oil bath by placing the cookware units exiting from the oil bath on a conveyor situated over the oil bath.

[0045] The step of retrieving the cookware units from the oil bath includes providing a partially submerged conveyor to move the cookware units out of the oil bath.

[0046] The step of controlling the temperature of the oil bath includes the step of cooling the oil in the oil bath to ensure that the oil bath doesn't reach a temperature within 20 degrees below smoke point. Preferably, the temperature is controlled by continuously cooling the oil in the oil bath.

[0047] The method further includes the step of adding texture to the surface of the cookware units prior to preheating the cookware units, for example by grit blasting or peening.

[0048] Following are the advantages of the quench method of seasoning of the present invention over the conventional industrial hang, spray, heat methods:

[0049] The ability to fully automate the process and exclude humans from the inherent hazards.

[0050] Lower costs per unit for seasoning when rate of plunging of cookware units is maximized by a large, cooled, oil tank and an oven matched to this rate.

[0051] Reduced smoke emissions.

[0052] More visually consistent results from the rapid, almost instantaneous, transformation of the oil to seasoning, evenly all over every surface the cookware unit (due to the temperature and cooling rate being the same all over).

[0053] Potentially harder and more durable seasoning coatings due to the higher temperatures (with higher smoke point oils), and faster cooling rates from quenching, than common hang, spray, heat production seasoning methods.

[0054] While only a single preferred embodiment of the present invention has been disclosed for purposes of illustration, it is obvious that many modifications and variations could be made thereto. It is intended to cover all of those modifications and variations which fall within the scope of the present invention, as defined by the following claims: