Patent Application
20150258389
The invention relates generally to a racket stringing machine and more specifically to a portable racket stringing machine with an improved string clamp and tension arm.
Tennis racket stringing machines come in many forms. Some racket stringing machines are set on pedestals and are positioned in a fixed location. This permits a user to stand in place and set the strings on a tennis racket. Such a method is sufficient when stringing a racket for the very first time in a factory setting. These pedestal machines often utilize an electric motor to provide the tension to the string during the stringing process. However, the use of such a machine is limited in other settings. Tennis players travel long distances to play in tournaments and strings may break while a racket is in use. Because of the size and weight of standard stringing machines it is not efficient to use such machines in multiple locations and portable machines are desired.
Portable machines are known in the art but are often still limited in structure. Often these stringing machines are structured to be placed on top of a table. To save on weight these machines to not use electric motors to provide tension on the string but instead use a drop weight or a hand crank. Machines utilizing a drop weight have a weight positioned on a rotational arm which is in turn attached to a string gripper. The drop weight may be slid up and down the rotational arm to change the tension which is set in the string. As the drop weight is slid further out along the arm the torque placed on the rotational arm increases, increasing the force a user must place on the rotational arm and thus the tension in the string. As the drop weight is slid lower on the rotational arm the torque placed on the rotational arm decreases, decreasing the force a user must place on the rotational arm and thus decreasing the tension in the string. This method of tensioning the string is sufficient in its ease of simplicity but is limited in that a heavy weight must be used. The heaviness and size of the weight required does not permit the racket stringing machine to be as lightweight and portable as may be desired.
Some portable stringing machines utilize a hand crank or an electromotor crank to provide tension to the string. However, these systems become overly complicated with many moving parts which may break during use or transporting. Additionally, these complicated systems increase the cost of producing the machines and thus increases the cost for the end user. What is needed is a portable racket stringing machine that provides the simplicity of the drop weight tensioning system, but is not as heavy as the drop weight system. Furthermore, what is needed is a portable racket stringing machine that is not as complicated to manufacture as those utilizing a crank or electric motor.
The invention is directed toward a portable tennis racket stringing machine which utilizes an advanced string clamp and tensioning lever. The invention is directed toward a tennis racket stringing machine comprising a base, a mounting plate, and one or more string clamps. The mounting plate has a plurality of channels shaped for receiving one or more string clamp feet. The string clamp has one or more string clamp feet shaped for being inserted into the channels. The string clamp is removably secured to the mounting plate when the string clamp feet are placed in the channels. The string clamp is positioned from above the string bed, lowered over the string bed, is secured to the mounting plate, and then is locked on a string during the stringing process. The string clamp is secured to the machine on one side of the string bed and locks on the other side of the string bed. Furthermore, the string clamp may further comprise a string clamp lock, a string clamp lever, and one or more fingers.
In one embodiment, the mounting plate may be movable along the plane of the string bed. A user positions the mounting plate in a desired location along the plane of the string bed, and locks the mounting plate in place prior to attaching the string clamp to the mounting plate.
In an alternative embodiment, the mounting plate is an immobile plate with the plurality of channels covering the substantial surface of the mounting plate. The plurality of channels is located substantially throughout the string bed area. This embodiment may further comprise a plurality of racket mounts and a rotational plate base. The rotational plate base is connected to the base so that as the base remains in a fixed position a user may rotate the rotational plate base. The mounting plate is affixed to the rotational plate base. Furthermore, the invention may further comprise a drum and a lever. The drum is attached to the base. The drum comprises a string gripper designed to secure a string during the stringing process, an immobile axle, and a brake. The drum rotates freely about the immobile axle. The lever comprises an external housing, a tension lever, a brake lever, and a tension spring. The tension lever is placed within the external housing and connected to the drum. The tension spring is positioned between the tension lever and the external housing of the lever. The tension spring connects the tension lever to the external housing of the lever. The brake lever is removably secured to the tension lever. When the tension in the string is equal to or greater than the tension in the tension spring, the tension lever compresses the tension spring. When the tension lever compresses the tension spring the tension lever detaches from the brake lever. When the brake lever detaches from the tension lever the brake lever engages the brake. When the brake is engaged the drum becomes immobile and locks into the then current position.
This embodiment may further comprise a brake release button. The brake lever disengages the brake when a user presses the brake release button. The brake release button may be located on the lever. Alternatively, this embodiment may further comprise a brake lever handle. The brake lever handle protrudes from the external housing of the lever and is an extension of the brake lever. A user may slide the brake lever handle distal from the drum to disengage the brake lever from the brake. In any of these embodiments the brake may be a torsion spring brake or a disc brake.
Furthermore, in any embodiment of the invention, the racket stringing machine may further comprise a slidable spring slot and a slidable spring head. The slidable spring slot is positioned along the longitudinal axis of the lever. The slidable spring head passes through the slidable spring slot and is connected to the tension spring. A user may change the tension set in the string during the stringing process by sliding the tension spring along the slidable spring slot. The tension spring is a slidable spring. In this embodiment the brake may be a torsion spring brake.
The invention is also directed toward a tennis racket stringing machine comprising a base, a rotational plate base, a mounting plate, a plurality of racket mounts, a table clamp, a drum, and a lever. The rotational plate base is connected to the base so that as the base remains in a fixed position a user may rotate the rotational plate base. The mounting plate is affixed to the rotational plate base. The table clamp is affixed to the base so that the table clamp permits a user to affix the base to planar surface. The drum is attached to the base. The drum comprises a string gripper designed to secure a string during the stringing process, an immobile axle, and a brake. The drum rotates freely about the immobile axle. The lever comprises an external housing, a tension lever, a brake lever, and a tension spring. The tension lever is placed within the external housing and connected to the drum. The brake lever is placed within the external housing and the brake lever has a brake lever handle protruding from externally from the lever. The tension spring is positioned between the tension lever and the external housing of the lever. The tension spring connects the tension lever to the external housing of the lever. The brake lever is removably secured to the tension lever. When the tension in the string is equal to or greater than the tension in the tension spring, the tension lever compresses the tension spring. When the tension lever compresses the tension spring the tension lever detaches from the brake lever. When the brake lever detaches from the tension lever the brake lever engages the brake. When the brake is engaged the drum becomes immobile and locks into the then current position.
In this embodiment the brake may be a torsion spring brake. This embodiment may further comprise a slidable spring slot and a slidable spring head. The slidable spring slot s positioned along the longitudinal axis of the lever. The slidable spring head passes through the slidable spring slot and is connected to the tension spring. A user may change the tension set in the string during the stringing process by sliding the tension spring along the slidable spring slot. The tension spring is a slidable spring. Furthermore, in this embodiment, the mounting plate may have a plurality of channels shaped for receiving one or more string clamp feet. In this instance the racket stringing machine further comprises one or more string clamps. The string clamp has one or more string clamp feet shaped for being inserted into the channels. The string clamp is removably secured to the mounting plate when the string clamp feet are placed in the channels.
The invention is also directed toward a process for stringing a racket. The process comprises placing a racket blank on a mounting plate, securing the racket blank to the mounting plate by means of a plurality of racket mounts, threading a string through the racket blank, securing the string on a string gripper attached to a drum, rotating a lever from a beginning position to apply tension to the string, lowering a string clamp over the string, placing the plurality of string clamp feet in a plurality of channels in the mounting plate, locking the string clamp onto the string, disengaging the brake lever, and rotating the lever to the beginning position. In this process the drum is attached to a base and the lever is connected to the drum. The lever comprises an external housing, a tension lever, a brake lever, and a tension spring. The tension lever is placed within the external housing and connected to the drum. The brake lever is placed within the external housing. The tension spring is positioned between the tension lever and the external housing of the lever. The tension spring connects the tension lever to the external housing of the lever. The brake lever is removably secured to the tension lever. When the tension in the string is equal to or greater than the tension in the tension spring, the tension lever compresses the tension spring. When the tension lever compresses the tension spring the tension lever detaches from the brake lever. When the brake lever detaches from the tension lever the brake lever engages the brake. When the brake is engaged the drum becomes immobile and locks into the then current position. The string clamp has a plurality of string clamp feet.
The process may further comprise rotating the mounting plate to rotate the racket and securing the string to the racket. The process may further comprise first securing the base to a planar surface by means of a table clamp. In this process the table clamp is attached to the base.
Although the present invention will be described with reference to the exemplary embodiments shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms or embodiments. In addition, any suitable size, shape or type of elements or materials could be used.
Referring to
When the base 105 is placed on the table, the drum 110 is positioned over the edge of the table. The string used to string the racket is secured in the string gripper 112 on the drum 110. The drum 110 has a lever 150 which rotates along a vertical axis. In other embodiments the lever 150 may rotate around a horizontal axis. The axis may also be oriented in any alternative position. As the lever 150 is rotated away from the base 105, as shown in
Referring to
The string clamp 200 is a unique improvement over existing string clamps. Existing string clamps rise from beneath the string bed to secure the string 10. In doing so the racket is mounted further away from the mounting plate to permit space for a user's hands. This requires a machine to be larger than necessary and the clamps must be larger than the string clamps 200 claimed herein. Additionally, existing string clamps only apply pressure on the string 10 from one side of the string 10 because the fingers are free floating and do not connect to anything. The string clamp 200 claimed herein, on the other hand, applies pressure from both above and below the string 10. The sting clamp 200 applies pressure below the string 10 when the string clamp feet 220 are secured in the channels 128 and the string clamp 200 applies pressure above the string 10 when the string clamp lock 230 is secured above the string 10. Because the string clamp 200 secures the string 10 from both above and below, the amount of pressure applied to the string 10 can be less than that applied by existing string clamps. Existing string clamps must generate a large amount of pressure to account for loss and inefficiency. Therefore, existing string clamps tend to break frequently. The string clamp 200 operates better than existing string clamps because the string clamp 200 does not have to generate as much force to secure the string 10.
Referring to
Tension is applied to the string 10 by a user primarily through the strength of the user. The end tension placed on the string is dependent upon the placement of the slidable spring 152 along the tension lever 154. The slidable spring 152 may move proximate to the axle 114 or distal from the axle 114 along the tension lever 154. The slidable spring 152 does not need to be precompressed, removing the tendency of the spring to fatigue through repetitive use. Optionally, the slidable spring may be compressed. Preferrably, the slideable spring is compressed to a slight degree. To change the applicable tension, a user may slide the slidable spring 152 along the tension lever 154. Moving the slidable spring 152 along the tension lever 154 changes the force and operation of the simple lever formed by the tension lever 154 and the axle 114. A user may begin with a standard tension where the slidable spring 152 is positioned distal from the axle 114. When a user moves the slidable spring 152 distal from the axle 114, the distance of the slidable spring 152 from the axle 114 is increased, while the distance of the string 10 from the axle 114 remains the same. Therefore the ratio of the simple lever changes resulting in a greater tension needed to trigger the brake lever 156. As a user moves the slidable spring 152 proximate to the axle 114, the distance of the slidable spring 152 from the axle 114 is decreased, while the distance of the string 10 from the axle 114 remains the same. Therefore the ratio of the simple lever changes, resulting in lower tension needed to trigger the brake lever 156. This causes a relatively smaller amount of tension to be placed in the string in the racket. Thus, to increase the tension, a user moves the slidable spring 152 distal to the axle 114. To decrease the tension a user moves the slidable spring 152 proximate from the axle 114.
In another embodiment of the invention, the slidable spring 152 may be replaced with a fixed spring which is in a fixed position on the tension lever 156. In this embodiment the user changes the tension by twisting the spring to change the compression level of the spring and thus the tension placed on the tension lever 150.
The racket stringing machine may be composed out of any type of material suited for commercial purposes. The components of the racket stringing machine may be made out of metal or a formed thermoplastic, or a combination thereof.
In separate embodiments of the invention, the brake may be any type of brake which may be utilized to lock the drum 110 in place about the axle 114. In the preferred embodiment the brake is a torsion spring brake 116. The torsion spring brake 116 utilizes a torsion spring wound about the axle 114. In another embodiment the brake may be a disc brake. Optionally, the brake may be an electromagnetic brake.
In separate embodiments of the invention the brake may be disengaged in any manner known. In the preferred embodiment, the brake lever 156 has a brake lever handle 145 which a user may move distal from the drum 110 to disengage the brake. The racket stringing machine may have a brake release button which mechanically or electronically causes the brake to disengage.
To utilize the invention the user first chooses the appropriate level of tension. Then the user secures the string 10 in the string gripper 112. The user then rotates the lever 150 away from the base 105. When the tension in the string 10 is equal to the tension in the slidable spring 152, the tension lever 154 compresses the slidable spring 152. As the slidable spring 152 is compressed, the tension lever 154 will move toward the side of the lever 150 with the slidable spring slot 140. The tension lever 154 will then detach from the brake lever 156. When the brake lever 156 detaches from the tension lever 154 the brake lever 156 slides toward the drum 110. When the brake lever 156 moves toward the drum 110 the torsion spring brake 116 is allowed to return to its natural state and tighten around the axle 114. When the torsion spring brake 116 tightens around the axle 114, the drum 110 no longer freely rotates about the axle 114. Thus the lever 150 becomes locked in place permitting the user to unhandled the lever 150 to continue the stringing process. When the user is ready to remove the tension from the string 10 the user grabs the brake lever handle 145 and moves the brake lever 156 distal from the drum 110 and secures the brake lever 156 to the tension lever 154. As the user moves the brake lever 156 away from the drum 110 the torsion spring brake 116 is pulled into an unwound and loosened position, permitting the drum 110 to once again rotate freely about the axle 114. The user may rotate the lever 150 back to the beginning position toward the base 105 and repeat the stringing process with the next length of string 10.
