US20090092935A1

US20090092935A1 - Method for effective degassing of wicks

Info

Publication number: US20090092935A1
Application number: US11/973,128
Authority: US
Inventors: John E. Cagle
Original assignee: Yankee Candle Co Inc
Current assignee: Yankee Candle Co Inc
Priority date: 2007-10-05
Filing date: 2007-10-05
Publication date: 2009-04-09

Abstract

A process for degassing or presoaking wicks used in the manufacturing of candles. Spools of raw wick are placed in a wax bath. The door to the vacuum chamber is then closed and the pressure in the chamber is reduced. The reduction of the pressure forces wax into the wick fiber to ensure complete saturation of the wick.

Description

BACKGROUND OF THE INVENTION

This invention relates to the preparation of candle wicks and more particularly to a process for degassing raw candle wick material.
The importance of raw wick degassing is well known in the candle industry. Raw wick is supplied to the candle industry in a dry form on cardboard spools in one to twenty pound spool weights. It is incumbent on the candle manufacturer to degas the wick prior to use for many candle applications. The degassing of the wick helps to ensure proper and consistent fuel flow during candle burning, via capillary action. If parts of the wick are not degassed properly the fuel flow can be altered (capillary action is reduced) resulting in variable flame heights. Variable flame heights can cause the burning candle to have intermittent smoking, decreased melt pool formation, and reduced hot throw (indicative of a low quality candle).
Another problem commonly found with improper wick degassing is called wick lean. During candle use the wick stance should be erect and upright from within the melt pool to the flame as shown in FIG. 1. When the wick stance is not erect and upright the wick is considered to be in a leaning position as shown in FIG. 2. The wick lean angle can exist in varying degrees up to greater than 45 degrees from the vertical where auto-extinguishing can occur. It has been shown that wick lean is primarily caused by improper wick degassing. The parts of the wick not effectively degassed are weak and lack adequate structural stability. The consequences of wick lean are off-center melting pool formation and potential auto-extinguishing of the candle's flame.
The typical wick degassing method used by both candle wick suppliers and candle manufacturers is the submerging of the dry wick into a melted wax bath for a period of time until air bubbles cease to rise to the bath's surface (caused by wax impregnating the wick). At this time the wick is considered degassed as shown in FIG. 3 b.
Wick degassing by wax submersion consists of one of two techniques:

- 1) Static Spool Submerging—In this technique, the entire spool of wick is submerged in a melted wax bath for a period of time. The spool is subsequently removed from the bath and left to solidify prior to final use. One cycle, start to finish, of nine spools of wick, 6.5″D×6.5″L, takes up to 4 hours of processing time.
- 2) Active “S” Loop Submerging—In this technique, wick is unwound from a dry spool through a melted wax bath using a series of “S” loops around “V” grooved pulleys and subsequently taken up on another spool. This method is physical process in that the “V” grooves help to force air out of the wick while submerged in the melted wax bath. This method is superior to Static Spool Submerging for effectively degassing a wick, but it can damage the wick by fraying. One cycle, start to finish, of one spool of wick, 6.5″D×6.5″L, can take up to 45 minutes of processing time. This technique is thought to be by far the most widely used technique for degassing wicks.

These two wick degassing techniques currently employed by both wick suppliers and candle manufactures are inconsistent and damaging to the wick material as well as not being conducive to high volume output. In Static Spool Submerging, the raw wick is supplied to the candle industry on spools. These spools vary widely in weight, density, and dimension. Larger and highly dense spools pose an issue with wax degassing. Upon submerging, the wax penetrates the wick fibers from the outside of the spool inward. These densely wound spools can insulate, to varying degrees, the inside wound parts of the wick from the molten wax which will result in an inconsistent partial degassed wick within a given spool. Another draw-back to this method is the unit output, 2.25 spools per hour is the average output. The rate is too slow to keep up with high volume manufacturing.
In Active “S” Loop Submerging a series of three to six wheels helps to ensure wick degassing by squeezing the air from the wick by unwinding the wick under the molten wax bath through a series of “S” loops around “V” grooved wheels of the type shown in FIGS. 4 a and 4 b. Damage is caused in this process when the squeezing effect frays the wick fibers causing damage to the overall wick construction. The fraying can affect capillary action by reducing the cross section of the wick. The reduced cross section carries less melted wax during candle burning resulting in lower flame heights. Another draw-back to this method is that the average unit output is 1.33 spools per hour. This rate is too slow to keep up with high volume manufacturing.
It is therefore a principal object of the present invention to provide a method for degassing wicks that process high volumes of wicks in less time than existing methods.
Another object of the present invention is to provide a method for degassing wicks that efficiently degasses entire spools of wicks.
It is another object of the present invention to provide a method for degassing wicks that causes minimal damage to the wicks, thereby ensuring consistent burn performance.

SUMMARY OF THE INVENTION

A process for the degassing or presoaking wicks used in the manufacturer of candles is provided for processing high volumes of wick. Spools of wick are loaded into a vacuum chamber. The door to the vacuum chamber is then closed and the pressure in the chamber is reduced. The spools of wick are then lowered into a molten bath and vacuum pressure released. The release of vacuum pressure forces wax into the wick fibers.
These and other features and objects of the present invention will be more fully described in the following detailed description which should be read in light of the accompanying drawings in which corresponding reference numbers refer to corresponding parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a fully upright wick.

FIG. 2 is a view of a wick suffering from wick lean.

FIG. 3 a is a cross sectional view of a wick prior to being exposed to the degassing process of the present invention.

FIG. 3 b is a cross sectional view of a saturated wick exposed to the degassing process of the present invention.

FIG. 4 a is a side view of a V-groove wheel used in Active “S” Loop submerging degassing techniques.

FIG. 4 b is a side view of the wheel shown in FIG. 4 a.

FIG. 5 is perspective view of a vacuum chamber without a door.

FIG. 6 is a front plan view of a vacuum chamber with spools placed within the chamber.

FIG. 7 a is a front view of the spool holder used in the vacuum chamber shown in FIGS. 5 and 6.

FIG. 7 b is a top view of the spool holder shown in FIG. 7 a.

FIG. 7 c is a side view of the spool holder shown in FIGS. 7 a and 7 b.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

This wick degassing process of the present invention uses vacuum technology. Wikipedia defines a vacuum as a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than standard atmospheric pressure. Standard atmospheric pressure is 760 torr. Referring to FIGS. 5 and 6, the vacuum used for the wick degassing process of the present invention is achieved in a vacuum chamber 20 of the type that, in a preferred embodiment is sold by Abbess Instruments and Systems, Inc. of Ashland, Mass. under the designation CHM-CB-AL-36-AC.
The vacuum chamber 20 is modified to include a wick spool holder 21 that is designed to hold nine spools at 6.5″ diameter×6.5″ long or six spools at 8′ diameter×12″ long. The wick spool holder 21 has three rods 34 equally spaced and it is placed in the vacuum chamber 20 horizontally. The spools 32 are slid on the rods 34 through the center of the spool 32. The spool holder 21 keeps the spools 32 suspended above the wax bath during the vacuum cycle and is then used to submerge the spools 32 into the wax bath and keep them submerged so they do float on top of the wax during the soaking cycle. In FIG. 6, two spool holders 21 are shown in both a position in the bath and a position out of the bath, and this is solely for illustrative purposes as there generally would only be one spool holder 21 in the chamber 20.
The mechanism used to lower and raise the spool holder 21 is an air actuated cylinder 36, which in a preferred embodiment is the cylinder sold by Parker Hannifin Corporation of Cleveland, Ohio under Model M02.200 TB4 MA 3 US 33A 17.000. The cylinder 36 has a 17 inch stroke. The cylinder 36 is mounted on top of the chamber 20 in vertical position with a modified seal for the base of the cylinder and the rod 37 of the cylinder inside the chamber 20. The end of the rod has a horizontal bar 40 attached to it. This bar 40 has a 15″ long pin 42 on both ends that are perpendicular to the bar in a horizontal position. The pins 42 are used to hold the spool holder 21.
The wax bath tank 48 is a square shape to match the inside of the chamber 20. The volume of the bath is about 30 gallons. The tank 48 is constructed of stainless steel with insulated side walls. The tank heaters, located underneath the bottom of the tank, are silicon rubber heating pads with Watlow controls. The wax temperature is controlled by a thermocouple in the wax tank 48 that maintains a temperature of between 65° F. to 250° F. The purpose of the wax tank 48 is to hold molten wax inside the chamber so that the spools then can be soaked in the molten wax for a determined period of time before releasing the vacuum. There is also a float sensor (not shown) in the tank 48 to prevent overflow of wax during replenishing of wax after the soaking cycle.
The whole system is controlled by a programmable logic controller 50, which in a preferred embodiment is sold by Schneider Electric of Coppell, Tex. under Model CB#20 24 v/dc which controls the air cylinder 36 and vacuum pump and valves to release vacuum. The programmable logic controller 50 also controls the time cycles for each step in the process as well as stack lights to indicate where the system is in the process and when all cycles are completed and processed spools are ready to be removed from chamber 20.
Air is removed from the chamber 20 by a vacuum pump. The vacuum pump and the chamber 20 are designed to adequately reduce the internal air pressure to less than 50 millitorr and preferably about 25 millitorr in about 15 minutes. At this level of vacuum, the chamber will encounter 19,000 pounds of force per wall.
The method utilized to degas the wicks in chamber 20 is simple, yet highly effective in degassing wick. The vacuum chamber contains a heated molten bath 24 The bath may contain any combustible material, typically wax or a blend of waxes, with a typical bath temperature range from 65° F. to 250° F., but preferably between 150° F. to 200° F. in a volume great enough to submerge up to nine spools of wick. Another major component within the vacuum chamber is a mechanism 26 to hold, lower, and rise up to nine reels of wick into the molten wax bath. The sequencing of the process is as follows:
1. With the vacuum chamber door 28 open, the operator loads up to nine spools 32 of wick into the chamber 20.
2. The door 28 is then shut and a vacuum pump 30 is engaged.
3. The vacuum pump will pull a vacuum down to less than 50 millitorr and preferably 25 millitorr.
4. Once 25 millitorrs is achieved, the spools 32 of wick are lowered into the molten wax bath 24 until they are completely submerged.
5. The vacuum is then released causing 16,900 pounds of force to be exerted on the molten wax bath 24 (containing the spools of wick).
6. The immense pressure forces wax into the wick fiber, ensuring complete saturation of wick and guaranteeing 100% degassing.
7. The spools 32 of wick are then raised and left to cool at ambient temperature, but cooler air may be used to accelerate the cooling rate.
8. The vacuum chamber door 28 is opened and the spools 32 of wick removed.
9. The cycle is then repeated with dry spools of raw wick.
10. Each cycle is less than 45 minutes and preferably 30 minutes.
In step 5 above, the tremendous amount of pressure used to force wax into the wick fiber is truly the center of this unique technology. There is more than adequate pressure to completely saturate the spool of wick, unlike the Static Spool Submerging technique, and will not physically harm the wick by fraying as in the Active “S” Loop Submerging technique. The method of the present invention in a chamber having 27 cubic feet has a unit output of about 18 spools per hour, of an approximate size of 6.5″ diameter by 6.5″ long, per hour. This rate is 8 times faster than Static Spool Submerging and about 13 times faster than the Active “S” Loop Submerging method. Moreover, this method can be used with any wick type (cotton core, square braid, flat braid, paper core, poly core, metal core, orientation specific, cellulose woven, oval, hybrid braids, knitted, etc.)
While the foregoing invention has been described with reference to its preferred embodiments, various alterations and modifications will occur to those skilled in the art. All such alterations and modifications are intended to fall within the scope of the appended claims.

Claims

1. A method of degassing candle wicks comprising the steps of:

placing wicks in a molten bath within a vacuum chamber;

reducing the atmospheric pressure within said vacuum chamber for a time sufficient to degas the wicks.

2. The method of degassing candle wicks of claim 1 wherein said wicks are placed in said vacuum chamber on a spool.

3. The method of degassing candle wicks of claim 1 wherein said atmospheric pressure within said vacuum chamber is reduced to less than 50 millitorr.

4. The method of degassing candle wicks of claim 1 wherein said wick are placed in said vacuum chamber on multiple spools.

5. The method of degassing candle wicks of claim 1 wherein said wicks are submerged in said molten bath for less than forty-five minutes.