TUBE PUNCHING AND COLLARING SYSTEM, DEVICE AND METHOD

Abstract

A tube punching system for punching at least one hole into a tube, said system comprising: a punch, an external mold and a counter die. The mold and punch are positioned relative to each other such that the mold exerts a counterforce onto the tube when the hole is punched; and wherein the mold subsequently forms a collar as a result of the force applied by punch against the tube.

Description

FIELD OF THE INVENTION

The invention relates to punching and collaring technology of tubes. More specifically, the present invention relates to tubes that may be used in solar heating, air conditioning and fluid conduction systems.

BACKGROUND OF THE INVENTION

Tubes that have a plurality of holes punched therein are in widespread usage as manifolds in many products such as solar heating panels.

In the art, several systems are in use enabling punching of holes into the wall of a tube.

In the art, an acceptable direction of punching is from the inner side of the tube to the outer side of the tube. Such a type of punching is hereinafter referred to as “punching a hole into a tube”.

However, in order to use such tubes as manifolds, the punching of holes into the tubes should preferably generate a collar around each hole to facilitate brazing of other tubes onto the tube manifolds.

The structure of the collar determines the quality of the brazing interface between the tube manifold and the parts thereon.

A known technique is making the hole and collar by a T-drill machine, developed by a company named T-drill. The machine drills the hole and makes the collar by turning fingers. The result is good but the process is slow and expensive due to tooling wear.

Another common technique is punching the tube from inside outwards, by a punch having smaller diameter cutting edge than the punch body diameter. The punch is forced out through the tube wall, and creates hole with collar. Such machine is made by Coilco from USA. The result of this process is good in production rate and tooling cost, but does not bring quality collar: the collar is conical and thus, does not assure brazing strength. Moreover, brazing material volume is relatively high.

It is an object of the invention to provide a way to punch tube and make quality collar in a more economic process.

Advantage of such a whole structure is in brazing manifold tube reliability and strength as well as in brazing material saving.

It is also an object of the invention to provide a novel way of scrap cutoff and removal off the machine. Scrap falls down unlike existing machines in which it falls around the punching point.

SUMMARY OF SOME EMBODIMENTS OF THE INVENTION

The present invention relates to a machine that combines a highly efficient punching method with a system and/or device that provides quality collar.

Generally speaking, a collar is examined by the similarity to a cylindrical shape, i.e., the similar a collar to a cylinder, the better is the quality of the collar, since a substantially cylindrical collar facilitates brazing of tubes on said collar.

It is to be understood that the term “punching a hole into a tube” or grammatical variations thereof, refer to a method wherein the direction of the punching is from the inner side of the tube to the outer side of the tube.

According to an embodiment of the invention, the present invention provides a method for punching at least one hole in a tube comprising the steps of: providing a system comprising a punch and a mold, placing the tube on the system such that the tube extends along a system axis, the punch is located within the tube and the mold is located outside of the tube, biasing the punch along a punch axis which is transverse to the system axis to make a hole in a wall of the tube, wherein at least a portion of the wall adjacent the hole is pressed between the punch and the mold to form a collar.

In some embodiments, the punch has an inclined surface. The punch is operated by a push bar having a surface that is substantially equal to the inclined surface of the punch.

In embodiments of the invention, the movement of the push bar is enabled by an external drive and by moving the push bar the punch is moved outwardly. The push bar is axially displaced towards the punch, such that an inclined surface of said push bar slides over the punch and thereby exerts a force onto the punch such that the punch is displaced in a direction which is substantially perpendicular to the displacement of the push bar.

In embodiments of the invention, the push bar may be propelled by, for example, a mechanical, a pneumatic, a hydraulic, and an electric or any other suitable drive.

In some embodiments of the invention, the collar is formed about the punch axis.

In some embodiments of the invention, during the biasing of the punch to make the hole the mold at least partially abuts the wall of the tube from the outside.

In some embodiments of the invention, the mold comprises a cavity that extends along the punch axis and opens out towards the tube, wherein at least a portion of the punch enters the cavity when making the hole in the tube.

In some embodiments of the invention, the at least portion of the wall adjacent the hole that forms the collar is pressed between the punch and the cavity of the mold.

In some embodiments of the invention, the system comprises a counter die, at least a position of the counter die being located within the cavity of the mold.

In some embodiments of the invention, the system comprises a biasing means that constantly biases the counter die towards the tube.

In some embodiments of the invention, at least a portion of the wall of the tube is pressed between the punch and the counter die when forming the hole.

In some embodiments of the invention, the external faces of the collar and tube merge via a radius wherein in a cross section including the system and punch axes the radius is optionally smaller than 1 millimeter, preferable smaller than 0.8 millimeter and further preferably smaller than 0.5 millimeter.

According to an embodiment of the invention, the present invention provides a system for forming at least one hole in a tube, the system comprising a punch and a mold, the tube when placed on the system extending along a system axis, the punch being located within the tube and being adapted to move along a punch axis that is transverse to the system axis, the mold being located outside of the tube and comprising a cavity that extends along the punch axis.

In some embodiments, the system comprises a counter die wherein at least a portion of the counter die is located within the cavity,

In some embodiments, the system comprises a biasing means that constantly biases the counter die towards the tube.

In some embodiments, the punch comprises an elliptical cutting edge wherein the major axis of the ellipse extends along the system axis.

In some embodiments, the mold is adapted to be biased towards and away of the tube.

In some embodiments, the counter die comprises a cavity extending along an axis substantially coaxial with the punch axis.

In some embodiments, the punch comprises a cutting edge, the cutting edge being adapted to be received within the cavity of the counter die.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention will become more clearly understood in light of the ensuing description of embodiments thereof, given by way of example only, with reference to the accompanying drawings, wherein

FIG. 1 is a schematic perspective front sectional view of a portion of a punching system that includes punching tools for punching a tube, wherein the punching tools are positioned adjacent the tube;

FIG. 2 is a side sectional view of the system during punching and collaring a tube;

FIG. 3 is an enlarged side view of the system during punching;

FIG. 4 is a schematic sectional side view of the system;

FIG. 5A is a schematic sectional side view of a punched tube; and

FIG. 5B is a schematic sectional front view of a punched tube.

The drawings taken with description make apparent to those skilled in the art how the invention may be embodied in practice. It should be understood that no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention.

It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

An embodiment is an example or implementation of the inventions. The various appearances of “one embodiment,” “an embodiment” or “some embodiments” do not necessarily all refer to the same embodiments.

Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment.

Reference in the specification to “one embodiment”, “an embodiment”, “some embodiments” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment, but not necessarily all embodiments, of the inventions.

It is understood that the phraseology and terminology employed herein is not to be construed as limiting and is for descriptive purpose only.

The principles and uses of the teachings of the present invention may be better understood with reference to the accompanying description, figures and examples.

It is to be understood that the details set forth herein do not construe a limitation to an application of the invention. Furthermore, it is to be understood that the invention can be carried out or practiced in various ways and that the invention can be implemented in embodiments other than the ones outlined in the description below.

It is to be understood that the terms “including”, “comprising”, “consisting” and grammatical variants thereof do not preclude the addition of one or more components, features, steps, integers or groups thereof and that the terms are not to be construed as specifying components, features, steps or integers.

The phrase “consisting essentially of”, and grammatical variants thereof, when used herein is not to be construed as excluding additional components, steps, features, integers or groups thereof but rather that the additional features, integers, steps, components or groups thereof do not materially alter the basic and novel characteristics of the claimed composition, device or method.

If the specification or claims refer to “an additional” element, that does not preclude there being more than one of the additional element.

It is to be understood that where the claims or specification refer to “a” or “an” element, such reference is not to be construed as there being only one of that element.

It is to be understood that where the specification states that a component, feature, structure, or characteristic “may”, “might”, “can” or “could” be included, that particular component, feature, structure, or characteristic is not required to be included.

Where applicable, although state diagrams, flow diagrams or both may be used to describe embodiments, the invention is not limited to those diagrams or to the corresponding descriptions. For example, flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described.

Methods of the present invention may be implemented by performing or completing manually, automatically, or a combination thereof, selected steps or tasks.

The term “method” refers to manners, means, techniques and procedures for accomplishing a given task including, but is not limited to those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the art to which the invention belongs.

The descriptions, examples, methods and materials presented in the claims and the specification are not to be construed as limiting but rather as illustrative only.

Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined.

The present invention can be implemented in the testing or practice with methods and materials equivalent or similar to those described herein.

The terms “bottom”, “below”, “top” and “above” as used herein do not necessarily indicate that a “bottom” component is below a “top” component, or that a component that is “below” is indeed “below” another component or that a component that is “above” is indeed “above” another component as such directions, components or both may be flipped, rotated, moved in space, placed in a diagonal orientation or position, placed horizontally or vertically, or similarly modified. Accordingly, it will be appreciated that the terms “bottom”, “below”, “top” and “above” may be used herein for exemplary purposes only, to illustrate the relative positioning or placement of certain components, to indicate a first and a second component or to do both.

The core section of an embodiment of a punching system 100 is schematically illustrated FIG. 1 and FIG. 2.

According to some embodiments of the invention, punching system 100 has a system axis X defining a forward to rear direction, and includes an axially extending mandrel 15 that passes through a housing 17. The rear end of the mandrel 15 (see FIG. 4) is attached to a machine frame. The system 100 has a punch 11 that is substantially concentric with a counter die 14 of the system 100. Punch 11 and counter die 14 extend along a punch axis P that is substantially perpendicular to the system axis X.

According to some embodiments of the invention, a push bar 16 of the system 100, located within mandrel 15, when in a rearward retreat position, enables punch 11 to be located inside mandrel 15. The rear end of the push bar 16 (not shown in FIGS. 1 and 2) is mechanically coupled to an output of a power unit 30, as schematically illustrated in FIG. 4.

According to some embodiments of the invention, a tube 22 to be punched, which is free to move along the axis X, is located about mandrel 15. Tube 22 having a radius Rt is optionally of a type used in solar heating, air conditioning and other fluid conduction system. Tube 22 for example may be made of copper, brass, aluminum or stainless steel.

Actuating wedge 19 of the system 100 (wedge 19 seen in FIGS. 1 and 2) which is not in contact with tube 22 is adapted to bias mold 13 along the punch axis P inwards towards the mandrel 15 and outwards away form the mandrel 15. This is optionally performed by key 50 of wedge 19 being urged to slide within key-way 51 of mold 13. Key 50 and/or key-way 51 are angled in relation to the punch axis P and thereby movement of wedge 19 towards axis P and away from axis P urges mold 13 to be biased along the axis P. The movement of wedge 19 is perpendicular to the punch axis P. It is noted that as mold 13 is biased towards the tube 22 and abuts the tube 22, it fixes the location of tube 22 along the axis X thereby temporarily disabling the tubes free movement along the axis X during punching. In addition it is noted that other mechanisms may be used to bias mold 13 towards and away from the tube 22. Yet further it is noted that instead or in addition to wedge 19, a biasing mechanism (not shown) may he used to displace tube 22 away and towards the mold 13. During punching the biasing mechanism biases the tube towards the mold and after punching the biasing mechanism biases the tube away from the mold to enable the tube to be axially displaced so it can be punched at another location.

When mold 13 moves out, it drags with it counter die 14, which is constantly inwardly loaded by a biasing means such as, for example, spring 18. Other loading mechanism may be employed. At a predetermined position of tube 22, a punching operation is carried out. FIG. 2 schematically illustrates the position of tube 22 where punching is performed. In the punching process, mold 13 is biased towards tube 22 by activating actuating wedge 19 and thereby imposes a counter force upon the outer face of the tube. During said process, counter die 14 is adjacent to tube 22 and push bar 16 moves forwardly so as to urge punch 11 to go outwardly to pierce the tube 22.

Attention is additionally drawn to FIG. 3. Counter die 14 has an axially extending internal cavity that opens out to an inner end of die 14 at an aperture 60. During the outward movement of punch 11, cutting edge 12 of punch 11 cuts the wall of tube 22 to produce a corresponding scrap 20 (see FIG. 2) that falls down and outwardly. In some cases scrap 20 will completely detach from tube 22 and thereby fall down as punch 11 meets counter die 14 with its cutting edge 12 passing through aperture 60 to be snugly received within the cavity of die 14. By continuing this outward movement, punch 11 flares the wall of tube 22, draws it between itself and cavity 10 of mold 13, thereby generating a collar 53 that has a substantially cylindrical shape that ends at a rim 25 (FIG. 5A). Cavity 10 of mold 13 has a diameter Dc.

In an embodiment, cutting edge 12 of punch 11 has an elliptical shape with major axis extending along the system axis X. It is noted that the shape of cutting edge 11 affects the curvature of rim 25 as viewed in a cross section that includes the system and punch axes X, P (FIG. 5A). The closer cutting edge 12 is to a circle the larger the curvature of rim 25 is in that view; and the closer cutting edge 12 is to an ellipse the smaller the curvature of rim 25 is in that view. The inventor has found that an elliptical or substantially elliptical shaped cutting edge 12 forms a rim 25 with a curvature that is favorable for attachment to lateral tubes. Such a rim 25 may differ from a straight line by optionally up to 1 millimeter or preferably up to 0.5 millimeters as viewed in a cross section including the system and punch axes X, P (FIG. 5A).

Attention is additionally drawn to FIGS. 5A and 5B. It is noted that mold 13 provides a counter force that assists in the formation of a collar 53 with a structure that is well adapted to connect to lateral tubes that may be brazed or connected thereto. A ridge 54 (FIG. 3) where cavity 10 of the mold 13 opens out of mold 13 inwardly towards the tube 22 has a radius R that forms a substantially corresponding external radius R2 at a join 55 between collar 53 and tube 22.

By way of a numerical example; radius R2 as measured in a cross section that includes the system and punch axes X, P (see FIG. 5A); may have the following dimensions. Optionally R2<1 millimeter, preferably R2≦0.8 millimeter, and further preferably R2≦0.5 millimeter. The inventor has found that a tube in accordance with an embodiment of the invention having the above R2 dimensions is better adapted for attachment to lateral tubes.

An imaginary cylinder C having a diameter equal to diameter Dc of cavity 10 is defined as located about the punch axis P (see FIG. 5B) and an imaginary curve 23 is located at the intersection of cylinder C and the outer surface of tube 22 around collar 53. It is noted that in planes perpendicular to the system axis X, curve 23 is located a distance substantially equal to Rt from the system axis X which in other words means that the outer surface of tube 22 maintains its cylindrical geometry adjacent collar 53. This geometry adjacent collar 23, which the inventor has found as favorable for attachment to lateral tubes, is due to tube 22 being pressed against ridge 54 of mold 13 during punching.

It is noted that tubes being punched by systems not having a mold 13 may exhibit deviations larger than 1 millimeter along their corresponding curves 23 that may affect the quality and strength of attachment of such tubes to lateral tubes. In addition it is noted that mold 13 enables tubes 22 with a wider range of hardness to be punched in the system 100. For example, tubes made of copper having a tensile strength of up to 400 [Newton/mm̂2] may be successfully punched in a system in accordance with the present invention due to the tube being pressed against mold 13 during punching. Punching systems that do not include a mold, upon which the tube is biased during punching, may exhibit the formation of cracks in the collar when punching for example copper tubes having a tensile strength as low as 300 [Newton/mm̂2]. It is noted that tubes having higher tensile strengths are cheaper therefore the usage of mold 13 in the system 100 enables cheaper material to be punched in the system 100. Mold 13 in addition serves as a guiding means for punch 11 as it enters its cavity 10. This guiding function of mold 13 has been found to increase the number of times punch 11 may be used in the system 100.

Design of system 100 can be numerous. In some embodiments of the invention, a power pack 30 is located at the rear end of system 100 (FIG. 4) or at any other suitable location in the system 100.

According to some embodiments of the invention, at this point, the rear end of mandrel 15 is mechanically coupled to a machine frame 31 and an actuator 27 moves push bar 16 that axially moves inside mandrel 15. The actuator is connected to the push bar via, e.g., coupling 26. It is noted that the axial movement of push bar 16 may be provided by various means. For example, the push bar may be actuated to move by hydraulic means, elect mechanical means etc. In addition it is noted that such means may be in some embodiments located within the manadrel 15.

While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the embodiments. Those skilled in the art will envision other possible variations, modifications, and programs that are also within the scope of the invention. Accordingly, the scope of the invention should not be limited by what has thus far been described, but by the appended claims and their legal equivalents. Therefore, it is to be understood that alternatives, modifications, and variations of the present invention are to be construed as being within the scope and spirit of the appended claims.

Claims

1. A method for punching at least one hole in a tube comprising the steps of:

providing a system comprising a punch and a mold,

placing the tube on the system such that the tube extends along a system axis, the punch is located within the tube and the mold is located outside of the tube;

biasing the punch along a punch axis which is transverse to the system axis to make a hole in a wall of the tube; wherein at least a portion of the wall adjacent the hole is pressed between the punch and the mold to form a collar.

2. The method according to claim 1, wherein the collar is formed about the punch axis.

3. The method according to claim 1, wherein during the biasing of the punch to make the hole the mold at least partially abuts the wall of the tube from the outside.

4. The method according to claim 1, wherein the mold comprises a cavity that extends along an axis substantially coaxial with the punch axis and opens out towards the tube, wherein at least a portion of the punch enters the cavity when making the hole in the tube.

5. The method according to claim 4, wherein the at least portion of the wall adjacent the hole that forms the collar is pressed between the punch and the cavity of the mold.

6. The method according to claim 1, wherein the system comprises a counter die and at least a portion of the counter die is located within the cavity of the mold.

7. The method according to claim 6, wherein the system comprises a biasing means that constantly biases the counter die towards the tube.

8. The method according to claim 6, wherein at least a portion of the wall of the tube is pressed between the punch and the counter die when forming the hole.

9. The method according to claim 1, wherein the external faces of the collar and tube merge via a radius.

10. The method according to claim 9, wherein in a cross section including the system and punch axes, the radius is smaller than 1 millimeter.

11. The method according to claim 9, wherein in a cross section including the system and punch axes, the radius is smaller than 0.8 millimeter.

12. The method according to claim 9, wherein in a cross section including the system and punch axes, the radius is smaller than 0.5 millimeter.

13. A system for forming at least one hole in a tube, the system comprising a punch and a mold, the tube when placed on the system extending along a system axis, the punch being located within the tube and being adapted to move along a punch axis that is transverse to the system axis, the mold being located outside of the tube.

14. The system according to claim 13, wherein the mold comprises a cavity that extends along an axis that is substantially coaxial with the punch axis.

15. The system according to claim 14, comprising a counter die wherein at least a portion of the counter die is located within the cavity.

16. The system according to claim 15, comprising a biasing means that constantly biases the counter die towards the tube.

17. The system according to claim 13, wherein the punch comprises an elliptical cutting edge wherein the major axis of the ellipse extends along the system axis.

18. The system according to claims 13, wherein the mold is adapted to be biased towards and away of the tube.

19. The system according to claim 15, wherein the counter die comprises a cavity extending along an axis substantially coaxial with the punch axis.

20. The system according to claim 19, wherein the punch comprises a cutting edge, the cutting edge being adapted to be received within the cavity of the counter die.