Woodworking – Planer – Rotary cylindrical cutter
Reexamination Certificate
2000-08-01
2003-07-01
Bray, W. Donald (Department: 3725)
Woodworking
Planer
Rotary cylindrical cutter
C144S130000, C144S114100
Reexamination Certificate
active
06585017
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a thickness planing apparatus. More particularly, this invention relates to a thickness planer having a carriage locking mechanism to minimize vibration and movement of the carriage during the planing operation. This invention includes a depth of cut indicator to display the thickness of the wood to be removed during the planing operation. This invention further includes a mechanism for facilitating setting the carriage and cutting head to a predetermined height over the to base, quickly and accurately for planing a workpiece to predetermined thicknesses.
2. Description of the Related Art
Planing a workpiece is a common operation in the field of woodworking. Planing is the removal of wood from a surface or face of a board so as to make it flat, uniform, and smooth.
It is generally known that a typical thickness planer is comprised of a base upon which support columns are perpendicularly mounted. Supported by the support columns is a carriage that houses a rotating cutting head. The cutting head has at least one cutting knife which, when rotated, removes material from the workpiece passing through the planer.
A lead screw is generally provided to adjust the height of the carriage above the base. Since the cutting head is rotatably attached to the carriage, the height of the carriage determines the thickness of the workpiece exiting the planer. The difference between the thickness of the workpiece entering the planer and the thickness of the workpiece exiting the planer is the depth of cut. The depth of cut is the thickness of the workpiece being removed by one pass through the thickness planer.
A motor-powered infeed roller pulls the workpiece into the planer, while an outfeed roller assists the workpiece to exit the planer. Also standard components on a known thickness planer are an infeed table and an outfeed table.
To provide versatility in a commercial thickness planer, it is common for the carriage to be adjustable to different heights. However, during the cutting operation, it is preferred that the carriage be securely attached to the housing of the thickness planer. Otherwise, vibration and movement of the carriage during the planing operation may produce undesired “snipe” or localized variations in the workpiece thickness. This undesired vibration and movement is especially prevalent when the workpiece is entering or exiting the thickness planer, i.e. at the beginning and end of a cut.
In some thickness planers, the base is stationary and the carriage moves to adjust the height of the carriage with respect to the base. In other versions of thickness planers, the carriage is stationary and the base moves to adjust the distance the base extends below the carriage.
Multiple attempts to provide carriage locks have been attempted. For example, U.S. Pat. No. 5,794,675 to Garcia discloses a locking assembly containing forks running the length of the support columns. By deflecting these long forks and sandwiching them between the carriage and the support columns, friction secures the carriage. Further, Garcia attempts to lock the carriage in line with the cutting head instead of locking the carriage at a location away from the cutting head. It has been found that the close proximity of the locking mechanism to the cutting head may not provide adequate stability when locking the carriage.
Another attempt to provide a carriage lock is disclosed in U.S. Pat. No. 5,771,949 to Welsh et al. Disclosed in this patent are various resiliently deflectable mechanisms having springs, levers, or more resiliently deflectable members to secure the carriage at a given height.
However, because of the geometries, systems of the prior art fail to produce a mechanical advantage to reduce the amount of force necessary to lock the carriage, compared to the holding strength of the locking mechanism. Further, because the systems disclosed in prior art systems rely upon resiliently deflected members, these systems over time fatigue and become less effective at securing the carriage. Further, the prior art systems utilize fixed links or rods to indicate the braking and locking action. Not only do these systems lose their effectiveness over time, but also they require maintenance of the worn, fixed links.
Thus, there is a need for a mechanism which minimizes the amount of snipe in a workpiece by minimizing the movement and vibration of the cutter head and carriage. Further, there is a need for the mechanism to require a small amount of force to lock the carriage into place, yet securely lock the carriage.
Thickness planers generally have a limit to the amount of material that should be removed in one pass, for a given type of cutting blade, motor size, etc. of a machine, and the material and the width of the workpiece. Manufacturers therefore often recommend a maximum depth of cut per planing operation. For example, a maximum depth of cut of ⅛ inch may be recommended for a six-inch wide wooden workpiece processed with a thickness planer. Therefore, there is a need to determine quickly and accurately the depth of cut without having to continually stop and manually measure the workpiece.
Various attempts have been made to automatically determine the depth of cut of a workpiece entering a thickness planer. For example, U.S. Pat. No. 5,927,357 to Welsh et al. discloses a workpiece indicator portion which is resiliently displaced by the entering workpiece. The resiliently displaced portion then deflects a pointer which moves along a scale mounted on the housing.
However, with this system, the repeated deflections of the resiliently displaced workpiece-engaging portion produces inaccurate results over time. Also, as this system relies upon the bending of the workpiece-engaging portion instead of a more positive-contact arrangement, inaccuracies result. Further, by having the scale mounted on the housing instead of the carriage itself, inaccuracies may result.
Often when planing wood, it is desired to produce workpieces of standard thicknesses, such as ⅛ inch, ¼ inch, ½ inch, etc. It is therefore desirable to have predetermined stops provided with a thickness planer to stop the carriage at a given height, thus producing finished product of standard thickness.
Various attempts have been made to produce predetermined stops for thickness planers. For example, U.S. Pat. No. 5,927,357 to Welsh et al. discloses a depth stop having three screws of varying heights attached to a rotatable main body. A portion of the main body resides directly below the carriage while the remainder of the main body resides outside of the travel area of the carriage. The height of the pin extending from the portion of the main body residing under the carriage therefore determines the height at which the carriage stops. By rotating the main body, one of three screws of different heights will determine the height of the carriage.
However, it is difficult to quickly and accurately determine at what height the screws are set, i.e. it is not an easy task to set the carriage height to produce a ¾ inch finished workpiece without performing a calibration process. Further, once one of the screws were set to produce the ¾ inch finished workpiece, one twist of that screw will de-calibrate the settings, requiring an operator to repeat the calibration process.
Thus, it is desirable to produce a thickness planer which can be more quickly, more easily, and more accurately set to produce predetermined thicknesses of workpieces than is available in the prior art. For the foregoing reasons, there is a need for a carriage locking mechanism that is capable of quickly and securely fixing the carriage at a given location above the base. Further, there is a need for an accurate depth of cut indicator. Finally, there is a need for a predetermined stop apparatus to allow an operator to quickly, yet accurately, set the carriage at predetermined heights. The claimed invention is directed at overcoming, or at least minimizing, disadvantages of the
Campbell Randall E.
Eckhoff Paul
Juei-Seng Liao
Bray W. Donald
Emerson Electric Co.
Howrey Simon Arnold & White , LLP
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