Abrading – Frame or mount – Portable abrader
Reexamination Certificate
2001-01-09
2002-05-28
Morgan, Eileen P. (Department: 3723)
Abrading
Frame or mount
Portable abrader
C451S344000
Reexamination Certificate
active
06394885
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a portable grinding machine with casing which is equipped with a rotor operated grinding tool on its front and a top handle on its back as well as a speed control mechanism with which the rotation speed can be regulated via a speed setting feature.
Grinding machines are used to remove coatings, lacquer and paint from surfaces of a variety of objects and are known for example from the EP 0 577 575 or the DE-PS 39 33 885. A possible area of use for these grinding machines is the removal of paint from the exterior surfaces of vehicles where it is necessary to follow the uneven lines of such a vehicle. For this, portable machines are being used which the user can hold with one hand and set onto the surface. The speed regulation needs to be adjusted multiple times for various tasks on one object depending on whether the full surface is being worked on or if edges or hollow moldings are involved. This is accomplished by a speed control mechanism, which is operated with the other hand. In order to change the speed the machine usually has to be taken off the surface because the pressure of the grinding tool onto the surface cannot be kept constant during the regulation of the speed which then could cause damage to the surface. On many known grinding machines the switch for the speed regulation is located below the flat of the hand. Another disadvantage of most common machines is that top handles in different sizes have to be used which need to be exchanged depending on the size of the hand of the user. This is especially true for use of the same piece of equipment by left or right-handed users and different hand sizes between men and women. These four different requirements by potential users can be addressed by making the top handles exchangeable so that each user can pick a top handle that is fitted more or less suitable for him or her. However, this involves extra cost, time and effort since the machine needs to be equipped with a different top handle, which then also needs to be securely and appropriately held in place.
SUMMARY OF THE INVENTION
The task of the submitted invention is to develop a portable grinding machine for which the speed can be adjusted easily without lifting the equipment off the surface of the object and which can be operated by various users without extensive conversions.
The task of the invention is solved by enabling the speed-setting feature to swivel around an axis perpendicular to the grinding machine and placing it at the upper edge of the top handle. This enables the user to operate the equipment with one hand. The inside of the hand or the palm is placed on the top handle on the back of the equipment while the fingers, especially the index or the middle finger can operate the speed setting feature. The speed setting feature is able to swivel around an axis essentially vertical to the grinding machine thus the same direction of the axis upon which the user applies pressure on the grinding machine. During the grinding process, the speed can continuously be changed and therefore adjusted to the objective of the work depending on whether the grinding machine is used with its complete grinding surface, partial surface or with its edge. An especially even and safe operation is made possible because only one hand applies pressure onto the equipment and the surface of the work object while setting the speed. Sudden, jerky motions during the application of the grinding machine onto the surface, which were inevitable when the speed was regulated by the other hand, can therefore be avoided.
The grinding machine can be operated especially well, if the speed setting feature is positioned so that holding the top handle and operating the speed setting feature with only one hand is possible and that the speed setting feature is within reach of the index or middle finger. For this reason, the speed-setting feature is placed directly below the covering of the top handle at the upper edge of the top handle so that this feature can be reached easily. At the same time, the distance in radial direction has to allow for an easily operation for the index- and middle finger. Therefore, it is assumed that the axis of the grinding machine and the top handle are the same.
The speed setting feature is placed on the outside of the casing and corresponds with an interior speed control mechanism. To connect the parts, the speed setting feature is directly connected to the speed control mechanism via a regulator ring which is located on the inside of the top handle and is mounted on a pivot. The axis of the regulator ring corresponds with the axis of the grinding machine and the top handle. The operation of the speed-setting feature moves the regulator ring around this axis and translates this motion onto the cylindrical speed control mechanism.
The regulator ring is equipped with a covering below which the speed setting feature juts out slightly, or better, the speed setting feature is placed above its radial limits jutting out slightly. It is understood, that the radial limit of the covering is at least almost identical to the radius of the motion of the speed-setting feature.
The invented grinding machine can be powered by pressure or electricity. Functionally, a pneumatic drive is envisioned which is equipped with a supply connection as well as a vitiated air connection while the supply connection correlates to an air intake valve into the rotor area. This air intake valve, detailed in the following text, is operated by a feature which can also be operated by the same hand.
An on/off switch located at the top handle, moveable towards the top handle and slightly jutting out will be the main device to operate the machine. This piece of the equipment is fit the form of the top handle so that it can also be operated by the back of the hand. To turn the machine on, the piece is pushed towards the top handle, or more precisely the grinding machine, against the pressure of a spring or turned around an appropriate joint. If the back of the hand is lifted slightly, the same part is pushed back into its off-position due to the pressure of the spring and moves away from the top handle, so that the machine will be turned off instantly due to the interruption of the pressure supply.
The operating device and the supply connection or air intake valve are connected through a valve pestle in the operating device, which correlates to the speed control mechanism. The side of the valve pestle, which faces away from the operating device has a connection to the air intake valve. By moving the operating device towards the top handle, the valve pestle is pushed along its longitudinal axis so that the air intake bores are opened and pressurized air can flow into the rotor area. If the operating device is moved in opposite direction, the valve pestle closes the air intake bores and the air supply will be shut off. By moving the pestle, the machine can be quickly turned on and off and by turning the speed control mechanism which surrounds the pestle the rotation speed of the grinding machine can be regulated for all settings between zero and maxim power.
To regulate the speed of the grinding tool, it is suggested that the speed control mechanism has at least one, preferably two drill-holes at its end pointing towards the air intake valve. These drill-holes correlate to a air intake bore in the air intake valve. By turning the speed setting control and therefore the speed control mechanism, the drill-holes at end of the speed control mechanism will be brought into position with the air intake bores.
A preferred version of the invention intends that the drill-holes and the air intake bores are built and set to cover each other partially or completely depending on the position of the speed control mechanism. Air flows via the supply connection or the air intake valve and the drill-holes into the rotor room, depending on how far one of these drill-holes overlap with the air intake valve. The revolutions per minute of the rotor can therefore be increased or d
Creighton Wray James
Morgan Eileen P.
Narasimhan Meera P.
Rodcraft Pneumatic Tools GmbH & Co. KG
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