Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-02-22
2001-02-27
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S388000, C099S342000, C432S009000, C432S011000, C432S121000
Reexamination Certificate
active
06194688
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an oven for baking coated parts and to a method of baking coated parts.
BACKGROUND OF THE INVENTION
Various products require a coating applied thereto to be baked to cure the coating so that it is fixed to the part. One example is that of circuit boards where a coating is applied and then baked. Another example relates to the powder coating of metal parts which is a relatively recent method for protecting and beautifying products. Powder coating makes a product highly chip and scratch resistant and a highly chemical, petroleum and salt resistant. Powder coating has the ability to apply a thick, even coat without drips or sags and has premium insulating qualities, both electrical and thermal and also removes the cold feeling from metals. It gives a decorative finish to a product along with a protective finish which is resistant to fading. Powder coating has the ability to encapsulate products, wrap around corners, help eliminate sharp edges achieve with one high quality coat with no primary necessary and can resist abuse in low and high temperature variances. Powder coating has virtually unlimited number of colours and a wide variety of finishes.
Generally powder coating is applied to many metal products powder coatings are 100% solids coatings applied as a dry powder mix of resin and pigment and subsequently formed into a film with heat. The solid resin binder melts upon heating, binds the pigment, and results in a pigment coating upon cooling. The powder is applied either by an electrostatic spray or by passing the part over a fluidised bed of powder. In both cases the parts undergo subsequent oven heating to provide a smooth continuous film.
Powder coated materials have to be heated in an oven or the like, an example of a powder coat oven is shown in U.S. Pat. No. 5,155,335 of Habaki et al wherein the oven has an inlet air shield chamber connected to a horizontal heating chamber. The oven of Habaki has a generally horizontal conveyor which is limited to one item at a time in the oven on the conveyor which is adequate for large items which need to be relatively spaced out but is not very effective for small items such as jewellery and the like.
U.S. Pat. No. 4,009,301 of Heckman et al discloses a method for powder coating materials. A large apparatus is used to carry items on a conveyor through a series of steps wherein the item is powder coated and baked.
U.S. Pat. No. 5,000,985 of Salisbury shows a similar method of powder coating wherein materials are carried on a conveyor through the processes.
The above patents are not effective for small objects and are relatively inefficient. it will be appreciated that the parts which are relatively small are generally suspended on the carriage from a hook or the like so that each is separate as it passes through the oven.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a baking oven and a method of coating parts which enables a user to bake a relatively large number of items at a simultaneously and be relatively efficient.
According to one aspect of the invention there is provided an apparatus for baking a batch of parts comprising:
a housing having closed side walls and a closed top wall defining an insulated and substantially closed top end and an open bottom end;
a heating element within the housing for generating heat in the housing such that the top end reaches an oven temperature for baking the parts;
a carrying arrangement in the housing for carrying the batch of parts;
a guide track system for guiding movement of the carrying arrangement from a first position exposed at the bottom end to a second position at the top end where the parts are heated by the heating element;
the carrying arrangement being arranged such that the batch of parts is loaded for heating at the first position;
the guide track system being arranged such that the carrying arrangement is moved vertically upwardly along the guide track system in a path from the first position to the second position, where the carrying arrangement is held stationary for heating of the parts, and is moved from the second position back to the first position vertically downwardly along the guide track system in the same path;
and a control system for controlling the heating element relative to the carrying arrangement such that the parts are heated in the second position and a second batch of parts can be attached to the carrying arrangement in the first position.
Preferably the control system includes a first locator at the second position for indicating when the carrying arrangement is at the second position and a second locator at the first position for indicating when the carrying arrangement is at the first position.
Preferably the guide track system includes first and second tracks each located on a respective one of two side walls in the housing, wherein a pair of wheel arrangements on the carrying arrangement engage each track and wherein a cable is supported by a series of pulleys for driving the carrying arrangement vertically upwardly and downwardly in the housing between the first and second positions.
Preferably the carrying arrangement has a removable rack comprising a series of hooks from which the parts depend.
Preferably the control system has a temperature control meter for controlling the heating element and a time control for controlling a dwell time during which the carrying arrangement is maintained at the second position.
Preferably the housing includes an air blower for circulating the heated air in the housing.
Preferably a ventilation outlet is arranged to remove toxic fumes from the housing and release the fumes outside into the atmosphere.
Preferably the housing has reflective inner walls to reflect infrared rays emitted by the heating element.
According to a second aspect of the invention there is provided a method for coating a plurality of parts comprising:
coating the parts with a coating material to be baked:
carrying the parts on a rack:
providing a baking oven having a housing having closed side walls and a closed top wall defining an insulated and substantially closed top end and an open bottom end;
providing a heating element within the housing for generating heat in the housing such that the top end reaches an oven temperature for baking the parts;
providing a carrying arrangement in the housing for carrying the batch of parts;
providing a guide track system for guiding movement of the carrying arrangement from a first position exposed at the bottom end to a second position at the top end where the parts are heated by the heating element;
loading the rack of parts on the carrying arrangement at the first position;
moving the carrying arrangement vertically upwardly along the guide track system in a path from the first position to the second position, where the carrying arrangement is held stationary for heating of the parts;
moving the carrying arrangement from the second position back to the first position vertically downwardly along the guide track system in the same path;
unloading the rack of parts at the first position;
and controlling the heating element relative to the carrying arrangement such that the parts are heated in the second position.
Preferably the rack is removable from the carrying arrangement and includes a series of hooks from which the parts depend.
Preferably the control system has a temperature control meter for controlling the heating element and a time control for controlling a dwell time during which the carrying arrangement is maintained at the second position.
Preferably the control system is arranged to maintain the heating element on as the parts pass the heating element while moving to the second position to apply a heat shock to the parts.
Preferably the control system is arranged to maintain the heating element off as the parts pass the heating element while moving to the first position to prevent application of excess heat to the parts.
Preferably the housing includes an air blower for circulating the heated air in the ho
Battison Adrian D.
Dahbour Fadi H.
Walberg Teresa
Williams Michael R.
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