Coaxial cable preparation tool

[0002] This invention is related to the field of power operated rotary strippers. More particularly, this invention relates to a tool that will prepare the butt end of semi-rigid coaxial cable for connector installation in a rapid and consistent manner.

[0003] Coaxial cable is used to transmit electrical signals. It comprises a center conductor, which is encapsulated by foam dielectric insulation. Furthermore, the foam dielectric material is overlaid with an outer conductor. Many times the outer conductor is an annular corrugated outer conductor or helically corrugated outer conductor. The entire assembly can be encased with an outer protective jacket. Coaxial connectors are used to connect coaxial cable to equipment to which it carries electrical signals to and from. Also, coaxial connectors are used to connect coaxial cables to each other.

[0004] To permit proper transmission of electrical signals, the coaxial connector is connected to the center and outer conductors of a coaxial cable. Therefore, before attaching the connector to an end of a coaxial cable, the end of a coaxial cable must be prepared. This involves stripping the coaxial cable's outer jacket and trimming the conductors and foam dielectric insulation. However, current methods for preparing semi-rigid coaxial cable for connector installation are slow and do not produce consistent results.

[0005] The present invention is a cable preparation tool, comprising a first stage and a second stage that is connected to the first stage. The first stage comprises a cylinder having a bore surrounded by an outer cylindrical wall. In addition, it comprises a base located on one end of the cylinder. A scrap port is located in the outer cylindrical wall and a blade is secured in the scrap port by a screw. The second stage comprises a body having a bore in its center and a hub located on an end of the body.

[0006] In another preferred embodiment, the present invention is a method of preparing a coaxial cable for connector installation, comprising the steps of inserting a cable preparation tool into an electric drill, actuating the drill and translating rotary motion of a second stage of the cable preparation tool to a first stage of the cable preparation tool. In addition, it comprises the steps of removing the coaxial cable's jacket by pushing the coaxial cable into the first stage. Next, the first stage is removed from the second stage. A collet is then installed onto an exposed cable outer conductor corrugation. Then the second stage of the tool is placed over the exposed cable and collet. Finally, the inner and outer conductors and the foam dielectric insulation of the cable are then trimmed.

[0007] FIG. 1A is a drawing of the first stage of the improved coaxial cable preparation tool.

[0008] FIG. 1B is a drawing of the second stage of the improved coaxial cable preparation tool.

[0009] FIG. 2 is a view of stage one of the improved coaxial cable preparation tool showing the base of the cup.

[0010] FIG. 3 is a view of stage one of the improved coaxial cable preparation tool showing the blade in the port.

[0011] FIG. 4 is a view of stage two of the improved coaxial cable preparation tool showing the bore with a white collet bearing.

[0012] FIG. 5 is a view of stage two of the improved coaxial cable preparation tool showing the spindle.

[0013] FIG. 6 is a flowcart of the operation of the improved coaxial cable preparation tool.

[0014] FIG. 7 is a view showing the assembled tool of the present invention with the first stage and the second stage connected together.

[0015] This invention relates to an improved coaxial cable preparation tool (1) that is used to prepare a coaxial cable terminal end for connector installation. The tool comprises two stages (FIGS. 1A and 1B). The first stage (10), the jacket stripper, is used to trim the cable jacket. The first stage (10) consists of a cup or cylinder (11) with an outer cylindrical wall (12). (See FIG. 1A). In addition, it also comprises a blade (13A) and a scrap port (14A). The blade (13A) is mounted in the scrap port (14A). In a preferred embodiment, the blade (13A) is secured in the scrap port (14A) using socket-head cap screws (15). (See FIG. 2). However, other means of securing a blade (13A) can be used. Also in a preferred embodiment, the blades (13A) used in the present invention are hardened tool steel blades (13A). However, other types of blades (13A) can also be used.

[0016] The first stage cylinder (11) has a bore (16A) extending axially down its center. The diameter of the bore (16A) is set to receive a coaxial cable. Extending into the cylinder (11) and communicating with the axial bore (16A) is the jacket trim port or scrap port or slot (14A) and jacket trim blade (13A) mounted in the jacket trim port (14A). (See FIGS. 2 and 3). The blade (13A) extends from the tangent of the axial bore (16A) radially inward into the axial bore (16A). The blade (13A) is accurately mounted in the slot (14A) in the outer cylindrical wall with screws (15). During operation (see below) the RF coaxial cable is pushed into the spinning bore (16A) of the first stage (10). The blade (13A) will remove the coaxial cable's jacket in a ribbon. The first cylindrical trim tool stage (10) will trim the cable jacket beyond the required amount for connector installation.

[0017] The second stage (20), the cable trimmer, (See FIG. 1B) is used to trim the remaining center, the outer conductors and the foam insulation of the coaxial cable. The second stage consists of a hub (21) (or cutter head), a collet bearing (22) and a body (23). (See FIG. 1B). In addition, like the first stage, it also contains a blade (13B) and a scrap port (14B). (See FIG. 1B). The scrap ports or debris ports (14A and 14B) allow trimmed cable media to escape from the bores in the tool.

[0018] The hub has a spindle (24) extending from its rear or back face (See FIG. 5). It is inserted into the chuck of an electric drill (Step 100 see FIG. 6), much the same way that a drill bit is inserted into a drill. The tool rotates at approximately 400 RPM about the cable end when in use. FIG. 7 shows the assembled tool of the present invention with the first stage (10) and the second stage (20) (or stage one and stage two) connected together. In a preferred embodiment, a locking pin (25) (see FIG. 1B) transfers torque from the hub (21) to the body of the second stage (20), and allows the hub (21) to translate in the body (23). In addition, the body (23) is connected to the first stage (10) via a twist-lock, or bayonet style connection (26) comprising a bayonet groove (26A) or female connector & a bayonet stud (26B) or male connector. (See FIGS. 1A and 1B). However, other types of connections can also be used to connect the first stage to the second stage. For example, a connection where the first stage (10) and the second stage (20) snap together can be used. In addition, the female connector (26A) can be located on said first stage (10) and said male connector (26B) can be located on said second stage (20) or vica versa. When the drill is actuated (Step 110), the bayonet (26) connection translates the rotary motion of the hub (21) to the first cylindrical stage (10) (Step 112). Therefore, when the drill is actuated, the cylinder (11), or first stage, rotates. The blade (13A) located in the first stage (10) removes the coaxial cable's jacket in a ribbon (Step 114). When the cable butts into the base (17) of the first stage (10), the trimming stops (see FIG. 7) (Step 115).

[0019] Next, the user removes the stripped cable from stage one (10) (Step 116). This is followed by removing stage one (10) from stage two (20) Vy unlocking the twist-lock bayonet style connection (Step 120). This exposes an axial bore (16A) and collet bearing (22) located within stage two (20) of the tool (Step 122). After this occurs, the user installs a collet (30) onto a prescribed cable outer conductor corrugation (Step 130). The collet is used to index the trimming of the cable. (The collet (30) is ordinarily supplied with the connector, or may be designed specifically for this tool if the connector does not require a collet). In a preferred embodiment, a locking spring (31) or retaining ring can be used to retain the collet bearing (22) within the second stage (Step 132). The spring (31) can be removed to replace a worn collet bearing (22) when maintenance is performed on the tool.

[0020] Next, the user places the second stage (20) of the tool over the cable so that the collet bearing (22) in the tool butts up against the collet (30) (Step 140). As discussed above, the hub (21) will trim the remaining center and outer conductors and also the foam insulation or dielectric insulation by plunging the hub (21) into and engaging the cable terminal end while rotating (Step 150). The second stage trim length is controlled by the collet bearing (22), which prevents the hub (21) from trimming any further. A debris port (14B) allow chips to escape during and after trimming.

[0021] As a result, the cable is consistently trimmed to a proper and consistent or repeatable length for connector installation relative to the cable corrugations and previous jacket trimming. Now, a connector can be installed over the cable. The user removes the tool stage two (20) from the cable by pulling the drill and the attached tool from the cable (Step 160). After cutting is complete, the user can clean the cable of debris to install the connector. After the first stage (10) is returned, the tool is ready for another trim.

[0022] While the invention has been disclosed in this patent application by reference to the details of preferred embodiments of the invention, it is to be understood that the disclosure is intended in an illustrative rather than in a limiting sense, as it is contemplated that modification will readily occur to those skilled in the art, within the spirit of the invention and the scope of the appended claims and their equivalents.