IE69551B1 - A process for producing brass fittings - Google Patents

Description

A process for producing brass fittings The invention relates to a process for producing brass fittings which includes the steps of hot stamping billets which have been prepared.

Hot stamping machines have been used for quite some time, one example of which is described in British Patent Specification No. 2,131,729 (Rovetta). Many different operations are required to prepare billets for hot stamping and to convert the output from a hot stamping machine to a finished brass fitting. These include coating billets and, after hot stamping, cutting excess flash, piercing the fitting to remove excess flash on internal bores, machining threads on the fitting and cleaning the fitting so that it not only looks acceptable but has a smooth surface for inter-engagement with other fittings. In carrying out these operations, there are considerable material and energy costs which arise because of the high price of brass, the heating requirement for hot ( stamping and indeed the electrical power for driving hot stamping machines. In a market where margins are tight, any scrap which is generated and energy wasted can make a considerable difference to viability of such production.

Ttct3 invention is thus directed towards providing a process for production of brass fittings which causes reduced scrap generation and wasted energy consumption. is directed towards achieving Further, the the optimum invention performance and quality output from machines in order to minimise capital costs. Finally, another object of the invention is to provide for production of fittings which are of a superior quality both functionally and aesthetically.

According to the invention, there is provided a process for 10 producing brass fittings comprising the steps of :inspecting brass rods for lack of uniformity and indentations; cutting rods into appropriately sized billets; coating the billets by rotating them in a polygonal15 shaped coating barrel containing approximately 15 ml of a graphite/oil mixture for 250 kg of billets; hot stamping the coated billets by manual feed to a hot stamping die for complex fittings, or high-speed automatic feeding for simple fittings; removing excess flash by operation of cutting and boring tools and automatically blowing debris from the cutting c tools to a chute for delivery to a bin; separating out fittings for which relatively small bores 5 are to be machined and subsequently burnishing* these fittings at a ball burnishing station, said ball burnishing station comprising a vibratory spiral of moisture-retention pellets in which the spiral is mounted for re-circulation of the fittings where desired, the station having a shut-off barrier for. directing the fittings from the end of the vibratory spiral to a chute if they are sufficiently burnished; carrying out any required machining operations on the fittings including said separated fittings; burnishing the separated fittings at de-greasing and acid dip stations to complete production of the separated fittings; categorising the remaining fittings according to the unmachined surface area and the structure; * routing small fittings which may be easily distorted by mechanical pressure through the de-greasing and acid dip stations to complete production of said fittings; . routing fittings having a relatively small un-machined surface through the ball burnishing station only to complete production of said fittings; and burnishing remaining fittings at the ball burnishing, de. 5 greasing and the acid dip stations.

In one embodiment, the balls of the ball burnishing station have a diameter in the range of 3 to 5 mm.

Preferably, the ball burnishing liquid is a mixture of an alkaline compound mixed with water and sodium bisulphate.

Preferably, the coating barrel is hexagonal and is rotated at 25 rpm.

The invention will be more clearly understood from the following description of some preferred embodiments thereof, given by way of example only, with reference to the accompanying drawings in which :Fig. 1 is a flow diagram illustrating a process of the invention; * Fig. 2 is a perspective view of a billet cutting machine used in the process; Fig. 3 is a perspective view of a machine used in the process for coating billets; and Figs. 4 to 6 inclusive are plan, side and perspective views showing a ball burnishing machine used in the process.

Referring to Fig. 1 there is illustrated a process of the invention for the production of brass fittings, indicated generally by the reference numeral 1. The process includes steps 2 to 14 and in step 2 brass rods of various dimensions are received and are inspected, particularly for lack of uniformity in diameter and for indentations or other damage which may have been caused either in manufacture or in transport of the rods. It is most important that the rods are uniform.

After inspection, rods which are of a relatively small diameter, i.e. up to 19 mm are cut in step 3 at a cutting station at which two of the rods are guided together to a rotating cutting blade, below which there is a disposal chute for cuttings. In parallel with this, rods having a large diameter are cut singly at a cutting station in step 4.

Referring now to Fig. 2, a billet cutting machine 19 for cutting two brass rods 20 together for step 3 is illustrated. The machine 19 includes a bed having inclined guides which support rods to move longitudinally under the action of a drive mechanism, not shown. The two rods 20 (having a diameter of 19 mm or less) are cut by a rotary cutter 22 controlled by a control unit 23. Billets 24 are also illustrated in Fig. 2. It has been found that billets of up to 19 mm are cut accurately in this manner without loss of quality.

At this stage, different sets of billets have been cut according to the size which is required for the particular fittings to be produced. For example, relatively small billets of 16 mm diameter and 25 mm length are used for production of cap nuts whereas billets of 30 mm diameter and 50 mm lengths are used for production of valves.

In step 5 the billets are coated with graphite to facilitate hot stamping. Referring to Fig. 3, graphite coating is particularly effectively carried out by loading the set of billets into a hexagonal shaped barrel 30 at a proportion of 250 kg of billets to 50 mis of a mixture of graphite and oil. The barrel 30 has a door 31 held securely in place by a bar 32 and is driven by a motor 33. The barrel is rotated at a speed of 24 rpm for approximately 30 minutes, after which the coated billets are removed. It has been found that by coating the billets in this way a particularly uniform distribution of graphite and oil is obtained on the billet which is extremely important for lubricating the billet and for reducing the defect rate for the hot stamping operations. In particular, * graphite and oil coating in this manner helps to prevent stress on the metal.

In step 6, the coated billets are categorised into two main 5 categories, namely, those for stamping at a hot stamping machine having manual feed and those for stamping at a machine having automatic feed. It has been found that for cap nut fittings automatic feed machines feeding at a rate of 3600/hr. are particularly suitable. Hot stamping using such machines is indicated by the numeral 7, and using manual feed machines by the numeral 8.

After hot stamping, excess flash both internally and externally of the stamp fitting is removed by use of clipping and piercing machines in step 9. Each machine has an air blower for delivery of air at a pressure of 6.8 bar so that the flash which is removed is immediately blown away towards a chute for delivery to a container. Thus, there is no remaining debris to interfere with further piercing and cutting operations. This is particularly important to ensure that the fitting is not damaged and that the flash is cleanly removed.

In step 10 various machining operations are carried out on the fittings such as the cutting of threads both internally and - 8 externally. Generally, the portions of the fitting which have been machined are of a finished-fitting quality.

The plant for producing the brass fittings includes three ΰ burnishing stations, namely, a de-greasing station, an acid dip station and a ball burnishing station. Burnishing at these stations are represented by the numerals 11, 12 and 13 respectively. The de-greasing station is of the Archimedes Scroll type in which a de-greasing agent is used for removal of grease as the fittings are conveyed in an upward spiral.

The acid dipping station includes a suitable acid bath 60% nitric acid for removal of dirt on immersion of the fittings into the bath.

Referring to Figs. 4 to 6 inclusive, a ball burnishing machine 40 of the invention is illustrated. The ball burnishing machine 40 comprises a trough 41 which is vibrated by a motor 42 with a variable weight off-centre output. At the output of the trough 41 there is a mesh 43 for holding fittings and allowing steel balls to drop through. The mesh 43 is vibrated by a motor 44 to feed an output chute 45. Steel balls are fed back through a feedback tube 46. The output chute 45 feeds a drying machine 50 which has a vibrator 51 which vibrates a spiral conveyor 52 at the end of which there is a mesh 53 from '* which fittings may drop to the beginning of the chute 52 which is underneath the mesh 53. A sliding grill 54 for directing fittings to a chute 55 and a container 56 is also provided.

In use, stainless steel balls of a diameter of 3 to 5 mm and a burnishing liquid to assist in the burnishing action are loaded into the trough 41. In this embodiment, the burnishing liquid is a 50/50 mixture of water and an alkaline burnishing compound added to 1.5 kg of sodium bisulphate for every 25kg of water/compound mixture. Moisture retention media pellets are loaded into the spiral conveyor 52 of the drying machine 50. Fittings are loaded into the trough 41 and on operation of the motor 42 these are conveyed in the left direction as viewed in Fig. 4 towards the output mesh 43. While being conveyed in the trough 41, the fittings are continuously burnished by the steel balls and scoring of the fittings is prevented and the burnishing action is assisted by the burnishing liquid. Both fittings and steel balls spill out into the mesh 43, upon which the fittings are conveyed by the vibratory action towards the chute 45, while the steel balls drop through the mesh and are fed back by the tube 46. Once in the spiral conveyor 52, the fittings are conveyed in an upward spiral direction and a vibratory action of the fittings in the media pellets dries the fittings and helps to enhance the brightness of the surfaces. The fittings are inspected after being conveyed once around the conveyor 52 and if sufficiently dry, the sliding grill 54 is moved across to direct the fittings downwards towards the container 53. If not sufficiently dry, the fittings are now dropped back to the beginning of the spiral to re-circulate.

Fittings which require relatively small machined through-bores of the same order of size as that of the burnishing balls are burnished at the ball burnisher before being machined and are subsequently put through both the de-greasing and the acid dipping stations. This avoids the balls being caught in the through-bore during burnishing. Small fittings which may be easily distorted by mechanical pressure are routed through the de-greasing and the acid dipping stations only because the mechanical pressure exerted at the ball burnishing station may damage or distort the fittings. This is particulary important for olives which have been annealed beforehand and are thus particularly susceptible to distortion by mechanical pressure. Fittings which are relatively rigid and would not be distorted and have a small un-machined surface are routed through the ball burnishing machine only, because this is sufficient to burnish the relatively small un-machined surface.

It has been found that the manner in which the fittings are burnished is crucial to the process as it avoids delays in production of a batch of fittings, maximises efficiency, while ensuring excellent quality of the fittings.

After burnishing, the fittings are assembled together as required to create completed fittings such as valves and tops. c» It will be appreciated that the production process of the invention is efficient as it optimises use of the various machines by for example, maximising use of automatic feed systems for hot stamping machines and using manual feed where this is most economical. Further, the use of three burnishing 4 stations and the manner in which the fittings are routed through the stations leads to a finished product which has a highly polished and clean appearance and burnishing is achieved with maximum efficiency by optimum use of the three burnishing stations. In the process, the manner in which billets are coated with graphite and oil is consistent and leads to a good quality and low reject rate for the hot stamping machines. Finally, the construction of ball burnishing machine leads to excellent finished product quality.

The invention is not limited to the embodiments hereinbefore described, but may be varied in construction and detail.

Claims (5)

1. A process for producing brass fittings comprising the steps of :inspecting brass rods for lack of uniformity and indentations; cutting rods into appropriately sized billets; coating the billets by rotating them in a polygonalshaped coating barrel containing approximately 15 ml of a graphite/oil mixture for 250 kg of billets; hot stamping the coated billets by manual feed to a hot stamping die for complex fittings, or high-speed automatic feeding for simple fittings; •ί removing excess flash by operation of cutting and boring tools and automatically blowing debris from the cutting tools to a chute for delivery to a bin; separating out fittings for which relatively small bores are to be machined and subsequently burnishing these fittings at a ball burnishing station, said ball burnishing station comprising a vibratory spiral of moisture-retention pellets in which the spiral is mounted for re-circulation of the fittings where desired, the station having a shut-off barrier for directing the fittings from the end of the vibratory spiral to a chute if they are sufficiently 5 burnished; carrying out any required machining operations on ι the fittings, including said separated fittings; burnishing the separated fittings at de-greasing and acid dip stations td complete production of the 10 separated fittings; categorising the remaining fittings according to the un-machined surface area and the structure; routing small fittings which may be easily distorted by mechanical pressure through the de-greasing and 15 acid dip stations to complete production of said fittings; routing fittings having a relatively small unmachined surface through the ball burnishing station A only to complete production of said fittings; and V- , 20 burnishing remaining fittings at the ball burnishing, de-greasing and the acid dip stations.

2. A process as claimed in claim 1, wherein the balls of the ball burnishing station have a diameter in the range of 3 to 5 mm. <

3. A process as claimed in claims 1 or 2, wherein the 5 ball burnishing liquid is a mixture of an alkaline compound mixed with water and sodium bisulphate.

4. A process as claimed in any preceding claim wherein the coating barrel is hexagonal and is rotated at 25 rpm. 10

5. A process substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.