MXPA01001972A - Dual-rated current transformer circuit - Google Patents

Abstract

A dual-rated current transformer circuit (10) has a first current line (12) which delivers a first current (IA) and a second current line (14) which delivers a second current (IB). A current transformer (20) is coupled to both the first and second current lines, wherein the transformer generates a current proportional to the current of each of the first and second current lines. The circuit can be miniaturized due to the input circuit which lowers the input current to the transformer and design techniques of the transformer which allow for size reduction.

Description

END OF CAN WITH A REINFORCED SIDE WALL AND APPARATUS AND METHOD TO MANUFACTURE IT FIELD OF THE INVENTION The present invention is directed to a can, such as a metal can used to pack carbonated beverages. More specifically, the present invention is directed to a can with one end with improved strength and to an apparatus and method for making this can.

BACKGROUND OF THE INVENTION Beverages, such as carbonated beverages, are typically packaged in cans made of a metal, such as aluminum. Two-piece cans are typically formed by attaching one end of the can to a can body. Traditionally, the joint is achieved by forming the can end 10, shown in Figure 1, in a die press. The can end 10 typically has a countersink flange 16, a substantially flat central section 18 and a junction section 13 terminating in a peripheral ripple 12, and a frusto-conical side wall portion 14, which extends between the flange and the flange. section of union. In the traditional manner, the side wall 14 is arranged at an angle A of approximately 14 ° with respect to a line parallel to the center line 7 of the body 20 of the can. (Subject to the contrary, the numerical value of all the angles referred to herein, should be understood as positive, which means that the angle tapers away from the center line of the body of the can, as it extends upward in the direction from the bottom of the can body towards the end of the can. the can. A negative angle is an angle extending toward the center line as it extends upward in the direction from the bottom of the can body toward the can end). The connection is made by placing a flange 11 of the can body 20 below the connecting section 13, at the can end 10. A joint chuck 2 is then inserted into the can end 10, as shown in Figure 1. Traditionally, the chuck chucks 2 have portions 4 and 6 of bottom and top wall, respectively. The lower wall portion 6 is typically located at an angle B, which is a few degrees less than the angle A of the side wall 14 of the can end, so that the angle A of the side wall of the can end at about 14 °, the angle B of the bottom wall of the chuck will be approximately at 11 °: The upper wall portion 4, which typically has a length L of about 3.3 mm, is typically disposed at an angle C that is approximately 4o . Thus, the upper and lower portions 4 and 5 intersect at the edge 5, so as to form an obtuse angle of approximately 173 ° (i.e., 180 ° + 4o-11 °) - Typically, the edge 5 has a radius of curvature of approximately 0.13 mm. Because the angle B of the lower wall 6 of the chuck 2 is smaller than the angle A of the bottom wall 14 of the end of the can, a relatively large space is formed, as much as 0.25 mm, between the side wall of the chuck and the side wall of the end of the can near the edge 5 of the wall of the can. chuck, as shown in Figure 1. The joint is completed by sequentially applying the first and second nip rolls against the ripple 12, in order to press the ripple and flange 11 against the upper wall 4 of the chuck, which produces a standard double joint 22, shown in Figure 2. Unfortunately, although it is pressed against the chuck 2 during the joint, the side wall 14 of the can end has to stretch back, ie, radially outwardly, when the pressure of the bonding roller is released. In this way, in spite of the fact that the upper and lower walls 4 and 6 of the conventional joint chucks 2 form two straight frustoconical sections, the side wall 14 'resulting from the end 10' of the can after joining, it is arched, with a relatively large radius of a curvature R (, as shown in Figure 2. The curved nature of the joined side wall 14 'weakens the strength of the 10' end of the attached can. developed a non-standard can end, in which the side wall after joining, is formed by two straight sections intersecting in a circumferentially extended groove. the published PCT application WO 96/37414. This structure is achieved by initially forming the side wall of the can end at a greater angle, considered to be preferred between the range of 40 ° to 45 °. In accordance with this measure described in this published PCT application, the joint chuck has a bottom wall disposed at an angle with equal dimensions and an upper wall disposed at an angle within a range of + 4 ° to -4 °. While this resolution results in a reinforced can end, unfortunately, the sidewall angle of the can end required for this resolution, prevents its application with standard can ends, in which the sidewall angle is only approximately 14 °, as previously described. Accordingly, it would be desirable to provide a method and apparatus for attaching a conventional end to a can, so that the attached end of the can has a side wall with improved strength.

BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to provide a method and apparatus for attaching a conventional end to a can so that the end of the attached can has a side wall with improved strength. These and other objects are achieved by a method of joining one end of the can to the can body, which comprises the steps of (i) forming one end of the can that having a side wall and a joining section, the side wall is formed by a single essentially straight section, arranged at an angle with respect to the central axis, which is within the range of approximately 12 ° to 15 °, (ii) inserting a chuck inside the end of the can adjacent to the side wall, the chuck has upper and lower portions, which form the upper and lower walls of the chuck, the lower wall of the chuck is essentially frustoconical and is disposed at an angle with respect to the axis not less than the angle to which the substantially straight section of the side wall of the can end is disposed, with respect to the central axis, the upper wall of the chuck is disposed at an angle with respect to the central axis which is within the range of approximately 0o to -2o; and (ii) attaching the junction of the end of the can with the can body so that the side wall of the can end again takes shape in essentially straight upper and lower sections, the essentially straight upper and lower sections intersect at an obtuse angle. The present invention also encompasses a chuck for use in joining one end of the can to the can body, which comprises: (i) an upper portion forming an upper wall, the upper wall is disposed at an angle with respect to the central axis that is within the range of about 0o to -2 °, and (ii) a lower portion, which forms a lower wall, the lower wall is essentially frustoconical and is disposed at an angle with with respect to the top wall which is within the range of about 162 ° to 168 °. The present invention also encompasses a attached can, which comprises: (i) a can body defining a central axis thereof, and (ii) an end of the can attached to the can body, the end of the can has a side wall formed by the essentially straight upper and lower sections, the essentially straight lower section being disposed at an angle with respect to the central axis which is within the range of about 12 ° to 15 °, the essentially straight upper and lower sections intersect at an obtuse angle to thereby form a circular groove separating the essentially straight upper and lower sections.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of one end of the can and a can body prior to joining, but after the insertion of a joint chuck into the end of the can, in accordance with the previous technique. Figure 2 is a cross-sectional view of the end of the can shown in Figure 1, after joining, in accordance with the prior art. Figure 3 is a cross-sectional view of the can end and can body prior to joining, but after the insertion of a joint chuck into the end of the can, in accordance with the present invention.

Figure 4 is a cross-sectional view showing the end of the can shown in Figure 3, attached in accordance with the present invention. Figure 5 is a cross-sectional view of the end of the can of the present invention after joining. Figure 6 is a detailed cross-sectional view of a portion of the chuck of Figures 3 and 4, in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY A novel method for attaching a conventional end 10 of a can to a conventional can body 20, in accordance with the present invention is shown in Figures 3 and 4. As described above, the end 10 The can is typically made of a metal, such as aluminum and formed in a die press using techniques well known in the field. The body 20 of the can is also made of a metal, such as aluminum and can be formed by an extraction and ironing process, again, using techniques well known in the field. The frustoconical side wall 14 of the end 10 of the can is also conventional, which extends between the flange 16 and the joining section 13, is arranged at an angle A with respect to the line 7 parallel to the longitudinal central axis of the body 20. of the can, whose angle is within the range of about 12 ° to 15 °, and preferably about 14 °.

Before joining, the flange 11 of the body 20 of the can is placed below the joint section 13 formed adjacent to the side wall 14 of the end of the can. A joint chuck 42, constructed in accordance with the present invention and described in more detail below, is inserted into the end 10 of the can adjacent the side wall 14, so that the distal end of the chuck enters the flange 16. The joint chuck 42 has an upper wall 44 and a lower wall 46 intersecting at a circumferentially extended edge 45. According to the present invention, the lower wall 46 of the chuck 42 is disposed at an angle B 'with respect to the line 7 parallel to the central axis of the can body, which coincides with the central axis of the chuck, which is very near the angle A of the side wall 14 of the end of the can. Specifically, the angle B 'should not be less than, and preferably slightly greater than, the angle A. Thus, when the angle A of the side wall 14 of the end of the can is disposed at a preferred angle of about 14. °, the angle B 'of the lower wall 46 of the chuck must be within the range of about 14 ° to 15 °. In gel, the angle B 'of the lower wall 14 of the chuck, in accordance with the invention, should be within the range of about A to A + 1 ° (since the standard can ends have sidewall angles in a range from about 12 ° to 15 °, as described above, the chucks 42 in accordance with the present invention, will have wall angles lower within the range of 12 ° to 16 °). As a result of this relationship between the end of the can and the wall angles of the chuck, in accordance with the present invention, there is not or very little space between the edge 45 of the side wall of the chuck and the end side wall 14. of the can, as shown in Figure 3, when the chuck is inserted into the end 10 of the can. In fact, preferably there is slight interference between the edge 45 of the chuck wall and the side wall 14 of the can end when the chuck 42 is fully inserted into the flange 16. In accordance with the present invention, the wall 44 of the chuck 42 is cylindrical or is slightly tapered in a negative man disposed at an angle C with respect to the line 7 parallel to the central axis which is within the range of approximately 0 to -2 °., and is preferably approximately -1 °. Thus, chucks 42 made in accordance with the present invention will have upper and lower walls 44 and 46 intersecting an obtuse angle D 'within the range of about 162 ° (i.e., 180 ° -2 ° -16 °). ) at 168 ° (ie, 180 ° -0 ° -12 °), depending on the angle A of the side wall 14 'of the end of the can to be joined. Preferably, the upper and lower walls 44 and 46 intersect at an obtuse angle of approximately 165 ° (i.e., 180 ° -1 ° -14 °), in case the side wall 14 of the can end is formed in a preferred angle of approximately 14 °. Importantly, this angle D 'is less than the angle D of about 173 °, traditionally associated with the joint chucks 2 for the conventional can ends 10, described above. As shown in Figure 6, preferably, a radius R 'within the range of about 0.025 to 0.51 mm, and preferably about 0.25 mm, is formed at the edge 45. Furthermore, the upper wall 44 of the chuck 42 has a length L ', indicated in Figure 3, of approximately 2.5 mm. Conventionally, the joining is carried out by sequentially applying a series of rotatable linking rollers 60, one of which is shown in Figure 4, to the corrugation 12 so that the forming surface 63 of the roller 60 presses the crimping and the flange 11 against the upper wall 44 of the chuck 42, which forms a double joint 62. By using the joint chuck 42 of the present invention, it results in one end 10"of the bonded can, like the shown in Figure 5. In contrast to the arcuate side wall 14 'of a conventionally attached can end 10, as shown in Figure 2, the side wall 14"of the end 10" of the can attached in accordance with the present invention, is segmented As shown in Figure 5, the side wall of the end of the can comprises a substantially straight upper segment 66 and a substantially straight frustoconical segment 68. The upper and lower segments 66 and 68 inte They extend to a circumferentially extended groove or curling 69. The essentially straight upper segment 66 extends from the junction 62 to the groove 69, and the frustoconically bottom, substantially straight segment 68 extends from the groove towards the flange 16. The angle A of the lower wall 68 of the end of the can with respect to the line 7 parallel to the central axis will generally remain without substantial change as a result of the joint in accordance with the present invention, and is within the range of about 12 ° to 15 °, and preferably about 14 °, as It was previously described. Although it is firmly pressed against the upper wall 44 of the chuck during joining, after joining, the upper side wall 66 of the can end will stretch back slightly, this is radially outward. Accordingly, the angle E of the upper side wall 66 of the end of the can with respect to the line 7 parallel to the central axis, will generally be within the range of about 0 ° to 2 °. Thus, at the ends of the can joined in accordance with the present invention, the obtuse angle F, in which the upper and lower side walls 66 and 68 intersect, will generally be within the range of approximately (180 ° -0 °). -A) to (180 ° + 2 ° -A), or approximately 165 ° (ie 180 ° + 0 ° -15 °) to approximately 170 ° (ie 180 ° + 2 ° -12 °), in case that the ends of the can are formed initially with the angle A of the side wall of approximately the range of 12 ° to 15 °. In case the end of the can is formed initially with the angle At a side wall of approximately 14 °, the side wall segments at the joined end of the resulting can intersect at an obtuse angle of about 166 ° (180 ° -0 ° -14 °) to 168 ° (180 ° + 2 °) -14 °). Importantly, the joint in accordance with the present invention, causes the side wall 14 of the can end to curl in a permanent manner, so as to form the segmented side wall comprised of two essentially straight sections, better than the side wall generally arched, unitary that resulted from the conventional joining methods, shown in Figure 2. This segmented wall structure is created, in part, by closely engaging the angles of the chuck and the side walls of the end of the can, so that no space is formed between the edge 45 of the side wall of the chuck and the side wall 14 of the end of the can. The absence of the radial space allows radially internal movement of the joining roll 60 to permanently deform the side wall of the can more quickly. The formation of the segmented side wall is also facilitated by the fact that the obtuse angle D 'of the chuck is small enough to result in a permanent kinking in the side wall during joining. In a surprising way, permanent kinking is achieved without using non-standard can ends, which have larger sidewall angles, as high as 45 °, which are considered necessary according to the prior art, as described above. Better, in accordance with the present invention, a kink can easily be formed during the joining of a conventional end of the can, which has a sidewall angle in the range of 12 ° to 15 °, by reducing the obtuse angle D ' , in which the chuck walls intersect at an angle no greater than approximately 168 °. Such a reduction in the obtuse angle D 'between the side walls of the chuck is created by employing an angle B' in the lower wall 46 of the chuck which is very close to or slightly greater than the angle A of the side wall 14 of the end of the chuck. can, as already described. This is contrary to conventional teachings of the art, which stated that the angle of the lower wall of the chuck should be several degrees smaller than the angle of the side wall of the can end, as described above. The reduction in the obtuse angle D 'in which the chuck walls intersect is also facilitated by forming the upper wall 44 of the chuck, so that, rather than being tapered in a positive manner as in conventional joint chucks, the wall The upper chuck is cylindrical or is slightly tapered in a negative way, as already mentioned. The use of an upper wall of the tapered or cylindrical chuck is considered unacceptable in the art due to the widely accepted claim that the measurement could make it difficult to tear the can end from the chuck. Surprisingly, the inventors have concluded that, with the chuck 42 in accordance with the present invention, the side wall 66 of the end of the can will stretch back far enough after the joint to allow the can end 10"to easily pull out of the can. drill chuck, even when the angle of the upper wall of the chuck is tapering negatively as much as -2 ° A 10"end of a can made in accordance with the present invention, with a segmented side wall comprising at least two portions 66 and 68 essentially straight frustoconical, it will have an improved strength, especially an improved tangential strength, when compared to the arched end side walls 14 'resulting from the conventional joining methods, shown in Figure 2. The present invention can be incorporated into other specific forms without departing from the spirit or essential attributes thereof, and in accordance with this, it should refer to the appended claims, better than in the previous specification, which indicate the scope of the invention.

Claims (7)

1. CLAIMS 1. A method for joining the end of a can with the body of a can, the can body defines a central axis thereof, which comprises the steps of: a) forming one end of the can with a wall lateral and a peripheral joining section, the lateral wall formed by a single essentially straight section, arranged at an angle A with respect to the central axis; b) inserting a chuck into the end of the can adjacent the side wall, the chuck has upper and lower portions forming the upper and lower walls of the chuck, the lower wall of the chuck is essentially frustoconical and is disposed at an angle B; and c) attaching the joint end of the can end to the can body so that the side wall of the can end can be reformed into a segmented side wall comprised of essentially straight upper and lower sections, the upper sections and essentially straight bottom intersect at an obtuse angle F; characterized in that the angle A with respect to the central axis is essentially within the range of 12 ° to 15 °, the angle B with respect to the central axis is not less than angle A, the upper wall of the chuck is disposed at an angle C with respect to to the central axis that remains essentially within the range of 0 ° to -2 °.
2. 2. The method according to claim 1, in where the obtuse angle F, in which the essentially straight sections of the side wall of the can intersect, is essentially within the range of 165 ° to 170 °. The method according to claim 1, wherein the joining step comprises reforming the end side wall of the can, so as to form a circumferentially extended groove, which separates the essentially straight upper and lower sections. The method according to claim 1, wherein the upper and lower walls of the chuck intersect an edge forming a radius essentially within the range of 0.025 to 0.51 mm. The method according to claim 1, wherein the end of the can also comprises a circular rim, the side wall of the can end being extended between the circular rim and the peripheral junction section. The method according to claim 1, wherein the top and bottom walls of the chuck intersect at an edge and wherein the step of inserting the chuck into the end of the can adjacent the side wall of the can end comprises insert the chuck, so that there is essentially no space between the edge of the chuck wall and the side wall of the end of the can. The method according to claim 6, wherein the step of inserting the chuck into the end of the can