GB2058625A - Making solder using pipe couplings - Google Patents

Abstract

Apparatus for and method of providing infils of solder in peripheral grooves of capillary couplings comprises a circular table rotatable on a centrally mounted shaft and carrying five holding means at equispaced radial positions adjacent to the tables circumference. The table is rotatable to bring each holding means sequentially into each of five stations where respectively from first to fifth stations a coupling (9) is located and clamped in one of the holding means, inserting means (23) locates the solder in the or each groove of the coupling (9), the solder is heated while the coupling (9) is being rotated, the solder is cooled while the coupling (9) is being rotated, and the coupling (9) is ejected. A feeding magazine (22) is provided with a coupling transfer arm (21) mounted to transfer couplings (9) one at a time from the magazine (22) to an empty holding means as it locates at the first station. The inserting means (23) inserts a ring preform of solder made by shearing and bending solder wire stock. In an alternative, molten solder is supplied. <IMAGE>

Description

SPECIFICATION Method and apparatus of providing solder infils in grooves of capillary couplings This invention relates to a method and apparatus for providing solder infils into peripheral grooves for such provided in the interior of metal capillary couplings, for example plumber's copper pipe couplings, the couplings being for use in joining together contiguous ends of two or three pipes, and the couplings being of different shapes such as straights for joining together two pipes in longitudinal axial alignment; bends for joining together two pipes whose longitudinal axes are angled to each other; or Tjunctions for joining together three pipes, two of which are in longitudinal axial alignment and the third having its longitudinal axis at right angles thereto.

Capillary couplings having interior peripheral grooves, one adjacent to each end, have been provided in which the grooves are infilled with solder. However, the existing method and apparatus for infilling the solder have disadvantages, namely that it is very time consuming in operation and after the solder, which is infilled in molten form, has solidified, it is necessary to ream out the interior of the coupling so that the level of solder in each groove is flush with the inner surface of the coupling. Increased production of these soldered couplings is thus hindered due to the time-consuming'delays in the existing method of providing solder infils.

It is an object of the present invention to obviate or mitigate the disadvantages of the above-mentioned method and apparatus.

According to the present invention, there is provided a method of providing solder infils in peripheral grooves in a capillary coupling, the method comprising the steps of locating a predetermined quantity of solder in the or each groove to be infilled in a coupling, and with the solder in a molten state, rotating the coupling about its axis at said groove at a speed to create sufficient centrifugal force to cause the molten solder to infill said groove and cooling said solder during rotation until the solder has set.

Preferably, the method includes the step of locating an open ring of solder-in wire form in the or each groove to be infilled and reducing the open ring of solder to a molten state by the application of heat while simultaneously effecting rotation of the coupling about its axis at said groove.

According to a second aspect of the present invention, there is provided apparatus for providing infils ofsolder, in grooves of a capillary coupling, the apparatus comprising means to hold a coupling, said means being rotatable, means to insert an open ring of solder in wire form into at least one groove of a coupling, and heating means to reduce the solder to a molten state while the coupling is being rotated by said holding means at a speed of rotation sufficient to create a centrifugal force to cause the molten solder to infil the or each groove.

According to a third aspect of the present invention, there is provided apparatus for providing infils of solder in grooves of a capillary coupling, the apparatus comprising means to hold a coupling, said means being rotatable and means to insert a predetermined quantity of molten solder into at least one groove of a coupling while the coupling is being rotated at a speed of rotation sufficient to create a centrifugal force to cause the molten solder to infil the or each groove.

Preferably, a plurality of holding means are provided on a circular indexed table which is rotatable on a centrally mounted shaft, the table being rotated to bring each holding means sequentially into each of five stations, namely a first station in which a coupling is located and clamped in a holding means, a second station in which the inserting means locates the solder in the or each groove of a coupling, a third station in which the solder is heated while the coupling is being rotated, a fourth station in which the coupling under rotation is cooled, and a fifth station in which the coupling is ejected.

Alternatively, a plurality of holding means is provided on a circular indexed table which is rotatable on a centrally mounted shaft, the table being rotated to bring each holding means sequentially into each of five stations, namely a first station in which a coupling is located and clamped in a holding means, a second station in which the inserting means locates molten solder in the or each groove of a coupling, while the coupling is being heated and rotated, a third station in which the solder is heated while the coupling is being rotated, a fourth station in which the coupling under rotation is cooled, and a fifth station in which the coupling is ejected.

Preferably also, a feeding magazine is provided having a coupling transfer arm mounted to transfer couplings, one at a time, to an empty holding means as the empty holding means locates at the first station.

Preferably further, each holding means is a chuck whose spindle passes through a boss rearward of the table, the spindle carrying at its other end one plate of a two plate friction clutch; a chuck release pin is provided on the plate for use at the fifth station. An electric motor is provided whose drive shaft carries the second plate of the clutch.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: FIG. 1 is a schematic side elevation of one embodiment of an apparatus according to the present invention; FIG. 2 is a front elevation of FIG. 1; FIG. 3 is a schematic side elevation of a second embodiment of the apparatus; FIG. 4 is a front elevation of FIG. 3; and FIGS. 5A, 5B, 5C and 5D are a series of four end views showing the sequence of steps in forming an open ring of solder from a length of wire.

Referring to the drawings and to both embodiments, an apparatus for providing infils of solder into grooves of a capillary coupling comprises a circular table 10 mounted on one end of a horizontal drive shaft 11, the table 10 carrying five holding means at equi-spaced radial positions adjacent to its circumference. Each holding means is mounted in a boss 12 extending rearward of the table 10, each holding means comprising a chuck 13 with finger clamps. The chuck 13 is located forwardly of the table 10 with its spindle 14 extending rearwardly through the pertaining boss 12 and terminating at its other end in one plate 1 5 of a two plate friction clutch 17. The other or second plate 1 6 of the clutch 1 7 is carried at the outer end of a drive shaft 18 of an electric motor 19, the location of which will be described hereinafter.Also carried on the outer face of plate 15 is a chuck release pin 20. The table 10 is rotated by a motor (not shown) at the other end of the drive shaft 11 to bring each holding means sequentially into each of five stations. At a first station, a coupling with a groove to be infilled with solder is located and clamped in the chuck 13 of one holding means. The coupling is located by a transfer arm 21 which transfer it from the discharge end of a downwardly inclined feeder magazine 22. The magazine is located at the bottom of a hopper (not shown). Couplings are gravity fed from the hopper to the magazine 22.

The transfer arm is actuable in both the axial and angular directions and is programmed to plug into and transport the couplings at the bottom of the magazine therefrom to the chuck positioned at the first station. At the second station located clockwise of the first (FIGS. 2 and 4), means to insert the solder is provided.In the first embodiment (FIGS.1 and 2), the means to insert solder comprises wire cutting and open-ring forming mechanisms shown at 23, the rings of solder wire being formed on a mandrel 24 which is then moved axially into the coupling 9 and expands to locate the open rings of solder in the pertaining grooves of the coupling 9. FIGS. 5A, SB, SC and 5D show the sequence of steps in forming the open ring of solder 7 on the mandrel 24 from a length of wire 8.

In the second embodiment (FIGS. 3 and 4), the means to insert solder comprises a fixed position melt-pot 25 into which solder in ingot form is fed, the melt-pot 25 being electrically heated and thermostatically controlled and divided by a thermal baffle 26 into an upper (Pre-melt) compartment 25A and a smaller volume lower compartment 25B. Each compartment is provided with one or more heating elements and sensors (not shown), the aim being to maintain the solder at delivery from the lower compartment 25B within close temperature limits and unaffected by the chilling which would otherwise result from introducing ingots at ambient temperature.

Conventional external thermal lagging can be used around the melt-pot 25 to conserve energy. An actuator-driven probe 27, programmed with a suitable dwell period (provisionally 1 second) delivers a metered volume of solder into each groove of the rotating coupling 9.

Within the probe 27 and oscillating with it, is a twin-barrelled piston pump 28 drawing molten solder under gravity via a non-return valve (not shown) and ejecting it through a second nonreturn valve (not shown). The pump 28 outputs are adjustable (to suit several coupling sizes) and a programmed pneumatic cylinder mounted at 29 drives the probe 27 and also the pump 28. Preheaters 30 are provided around the coupling 9 as shown.

In the second embodiment, the motor 19 is mounted behind the second station to spin-up the pertaining chuck 13 as the solder is being inserted to create centrifugal force to evenly distribute the solder in the grooves.

At the third station, heating means in the form of four (two pairs) constant-flow heating nozzles 31 are provided to be around the coupling 9 when in the station.

In both embodiments, each station at which solder in a liquid molten state is located in a groove of a coupling clamped in a chuck is provided with means for spinning-up the chuck, and at those stations, namely the fourth station where the solder is cooling and is in a semi-molten state the chuck free-wheels under its own momentum. Therefore, in the first embodiment, a motor 19 is mounted behind the third station to spin-up the pertaining chuck 13 to create sufficient centrifugal force to evenly distribute the solder in the grooves as the rings of solder are reduced to a molten state. In the second embodiment, a motor 19 is mounted behind each of the second and third stations or alternatively behind the second station as shown in FIGS. 3 and 4, and drive transferred by belt to rotate the third station, omitted in FIGS. 3 and 4.At the fourth station, cooling means in the form of two diametrically opposed constant flow nozzles 32 are provided to be around the coupling 9 when in this station. At the fifth station, a chuck release roller 33 (FIGS. 1,2 and 4) engages the chuck release pin 20 to eject the solder infilled coupling.

The holding means are freely mounted in the pertaining bosses and the finger clamps of the chucks 13 number three and are equi-spaced. The finger clamps are suitably profiled and springloaded to locate on one of the fluted rings of a coupling 9. Suitable lead-in chamfers permit entry with a 'snap action'.

Where oscillatory movements are required, it is proposed that pneumatic actuators are used, the programming signals being taken from cams mounted on the constant speed input drive shaft.

Where the signal effort is limited, sensors using low pressure air to switch high pressure actuators may also be used (e.g. to control the solder wire feed in the first embodiment).

In the first embodiment, solder (60/40 lead/tin) in wire form and of a suitable diameter for the fitting size, is taken from two reels (not shown) and is pulled through a light friction brake by rollers 34. The lower rollers are continuously driven and the wire feed is stopped by releasing the upper roller load when sensors detect the ends of the wires. The latter are then sheared and wrapped around the mandrel 24 as indicated. This assembly is then programmed to enter the stationary coupling 9 at the second station where, by expanding and contracting the mandrel 24 the two wire rings are deposited within the corresponding grooves.

Blast cooling may be extended into the fifth station by suitable positioning of nozzles.

The above-described method and apparatus are based on the centrifugal casting of solder in the annular grooves of couplings by rotating the coupling while applying heat and has the following advantages: 1. The high centrifugal forces acting on the relatively dense molten solder, consolidates it, eliminating trapped air which would cause porosity.

2. The maximum possible volume of solder is introduced, thereby improving the joint efficiency of the coupling.

3. Little or no loads are applied to the fittings during the process so that wear and hence maintenance of mating plugs etc., is minimal.

4. A measured quantity of solder is introduced into each fitting thereby reducing waste to a minimum.

Indexing means (not shown) are provided to index the table 10 from one station to the next station in the sequence.

Claims (13)

1. A method of providing solder infils in peripheral grooves in a capillary coupling, the method comprising the steps of locating a predetermined quantity of solder in the or each groove to be infilled in a coupling, and with the solder in a molten state, rotating the coupling about its axis at a speed to create sufficient centrifugal force to cause the molten solder to infil said groove, and cooling said solder during rotation until the solder has set.

2. A method as claimed in Claim 1, including the step of locating an open ring of solder in wire form in the or each groove to be infilled and reducing the open ring of solder to a molten state by the application of heat while simultaneously effecting rotation of the coupling about its axis.

3. An apparatus for providing infils of solder in grooves of a capillary coupling, the apparatus comprising means to hold a coupling, said means being rotatable, means to insert an open ring of.

solder in wire form into at least one groove of a coupling, and heating means to reduce the solder to a molten state while the coupling is being rotated by said holding means at a speed of rotation sufficient to create a centrifugal force to cause the molten solder to infil the or each groove.

4. An apparatus for providing infils of solder in grooves of a capillary coupling, the apparatus comprising means to hold a coupling, said means being rotatable, and means to insert a predetermined quantity of molten solder into at least one groove of a coupling while the coupling is being rotated at a speed of rotation sufficient to create a centrifugal force to cause the molten solder to infill the or each groove.

5. Apparatus as claimed in Claim 3, wherein a plurality of holding means is provided on a circular indexed table which is rotatable on a centrally mounted shaft, the table being rotated to bring each holding means sequentially into each of five stations, namely a first station in which a coupling is located and clamped in a holding means, a second station in which the inserting means locates the solder in the or each groove of a coupling, a third station in which the solder is heated while the coupling is being rotated, a fourth station in which the coupling under rotation is cooled and a fifth station in which the coupling is ejected.

6. Apparatus as claimed in Claim 4, wherein a plurality of holding means is provided on a circular indexed table which is rotatable on a centrally mounted shaft, the table being rotated to bring each holding means sequentially into each of five stations, namely a first station in which a coupling is located and clamped in a holding means, a second station in which the inserting means locates molten solder in the or each groove of a coupling, while the coupling is being heated and rotated, a third station in which the solder is heated while the coupling is being rotated, a fourth station in which the coupling under rotation is cooled, and fifth station in which the coupling is ejected.

7. Apparatus as claimed in Claim 5 or 6, wherein a feeding magazine is provided having a coupling transfer arm mounted to transfer couplings, one at a time, to an empty holding means as it locates at the first station.

8. Apparatus as claimed in Claim 5, 6 or 7, wherein each holding means is a chuck whose spindle passes through a boss rearward of the table, the spindle carrying at its other end one plate of a two plate friction clutch; a chuck release pin is provided on the plate for use at the fifth station.

9. Apparatus as claimed in Claim 8, wherein at least one electric motor is provided whose drive shaft carries the second plate of the clutch.

10. A method of providing solder infils in grooves of capillary couplings substantially as hereinbefore described with reference to FIGS. 1 and 2 of the accompanying drawings.

11. A method of providing solder infils in grooves of capillary couplings substantially as hereinbefore described with reference to FIGS. 3 and 4 of the accompanying drawings.

12. An apparatus for providing infils of solder substantially as hereinbefore described with reference to FIGS. 1 and 2 of the accompanying drawings.

13. An apparatus for providing infils of solder substantially as hereinbefore described with reference to FIGS. 3 and 4 of the accompanying drawings.