GB1596070A

GB1596070A - Method of manufacturing a nozzle for discharging liquids at relatively high pressures and nozzles produced by the method

Info

Publication number: GB1596070A
Application number: GB22247/78A
Authority: GB
Original assignee: SPECK KOLBENPUMPEN FABRIK
Current assignee: SPECK KOLBENPUMPEN FABRIK
Priority date: 1977-05-27
Filing date: 1978-05-25
Publication date: 1981-08-19
Also published as: IT7823750A0; IT1095521B; DE2724173C2; DE2724173A1; DK234478A

Description

(54) A METHOD OF MANUFACTURING A NOZZLE FOR DISCHARGING LIQUIDS AT RELATIVELY HIGH PRESSURES AND NOZZLES PRODUCED BY THE METHOD (71) We, SPECK-KOLBENPUMPEN FABRIK OTTO SPECK KG a German Company of 8192 Geretsried 1, Postfach, 1240, Elbestr. 8 do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The invention relates to a method of manufacturing a nozzle suitable for discharging liquids at relatively high pressures and to nozzles produced by the method.

Prior art discharge nozzles are known for discharging liquids at relatively high pressures and generally comprise a discharge nozzle having a supply passage leading to the nozzle opening and a recess downstream of the nozzle opening which forms an air circulation zone adjacent the discharge.

Discharge nozzles of this type are for example extensively used for cleaning apparatus to produce a uniform distribution of liquid for the treatment of surfaces.

Stringent requirements have to be set for such discharge nozzles in respect of accuracy because the most trivial differences in flow cross section result in large pressure differences with the high pressures that are presently customary and which, for example in cleaning installations, are far in excess of 100 bar and are being increased yet further.

Despite a considerable degree of expense and trouble in the technical manufacture of the known nozzles of this kind considerable difficulties exist in guaranteeing the required accuracy. Moreover it has been found in practice that after a comparatively short operational life changes of the discharge nozzle characteristics frequently occur which have the consequence that the intended working pressure can no longer be achieved and thereby that the overall efficiency of the cleaning installation reduces in disadvantageous measure.

The known discharge or spray nozzles are generally so manufactured that a supply bore or passage of exact pre-determined depth is produced in the nozzle body, generally by means of a special tool, and that subsequently the nozzle end face is so ground or milled away that the resulting shaped nozzle opening is formed by the intersection of two curves.

Thus, by choice of a desired ground profile and depth of cut, the desired shape of the nozzle opening is produced. The recess that is obtained by grinding or milling in the end face of the nozzle body protects on the one hand against eventual damage to the nozzle opening and brings on the other hand the necessary sideways air circulation at the jet for the avoidance of the formation of drips.

Taken into account the very small nozzle openings required, which by such nozzles lie in the range of millimeters, the most stringent requirements must be set not only during the boring process but also during the milling or grinding operation because even the most trivial inaccuracies result in deviations in the curved sectional form and size of the nozzle opening.

These requirements are made more difficult to achieve because the resulting curved shape is achieved by means of working processes from opposite directions which means that a burr is formed, in the region in which the curves intersect to form the nozzle opening, which must be completely removed in order to avoid influencing the jet by this burr or its remains.

The deburring takes place in the known nozzles by sand blasting whereby once more it is necessary to work exceptionally accurately and for which the duration of the sand blast operation must be exactly predetermined because the sand blast can change the sharp lipped curve which defines the nozzle opening.

Even when the most exacting accuracies are met in manufacture, including taking into account the necessarily continuously occurring wear of the manufacturing tools, so that the most extensively exact predetermined nozzle openings are achieved, problems occur in the practical application of these nozzles which manifest themselves as a change of the nozzle characteristics. So, for example, with the use of such discharge nozzles in spray guns for cleaning installations it frequently happens, over a short period, that the achievable working pressure significantly drops away. This is generally a consequence of the occurrence of erosion at the sharp lipped nozzle opening.

Because the occurrence of a loss of power through drop in pressure generally means an after sales service is necessary even a single change of such a nozzle means considerable costs and inconvenience are incurred.

Attempts to remove these difficulties by a further increase of the accuracy of manufacture and through the use of special materials have not shown themselves to be successful because, especially with the use of harder metals to better withstand erosion, the difficulties of manufacture increase and even higher requirements must be set for the tools.

The problem underlying the invention is to so construct a discharge nozzle that a relatively long working life with practically unchanged characteristics is obtained with a simultaneous simplification of the manufacture and with the guarantee of exact predetermined nozzle openings.

According to the present invention there is provided a method of manufacturing a nozzle for discharging liquids at relatively high pressure, the method comprising the steps of: a) boring a supply passage of circular cross-section into one end of a metal nozzle blank, whereby the end portion of said bored passage is continuously tapered with out steps and terminates short of the end of the nozzle blank, b) machining a recess into the opposite end of the blank and wherein, as a result of steps (a) and (b) there results a nozzle blank in which the said supply passage and the said recess are separated by a wall of metal, c) selecting a punch having an operative elongate tip of constant cross-section with a major cross-sectional dimension smaller than that of the supply passage and intro ducing the tip of the punch into the supply passage, d) punching the punch tip through the wall of metal between the supply passage and the recess whereby to produce a dis charge passage with parallel sides and a cross-section corresponding to that of said operative elongate tip and defining the pro file of the jet discharged from the nozzle, wherein the tapered end portion of said supply passage provides in operation an advantageously shaped flow guiding surface.

Through this measure a plurality of surprising advantages are achieved which above all are to be seen in the fact that the requirements set for the accuracy of manufacture during the boring, grinding or milling procedures no longer need to be so stringent because the nozzle characteristic is determined during the execution of the punching procedure by the shape of the punch. This has the result that in the practical use considerably higher service lives are simultaneously achieved without the occurrence of the undesired drop in pressure, this being a consequence of the fact that the punching operation results in a, in comparison to the previously customary sharp lipped nozzle opening, more stable discharge passage of finite length with exact predetermined dimensions which is practically unaffected by erosion effects.

By the method of the invention the advantage is obtained that the burr resulting from the punch procedure lies at the exterior of the discharge passage and is therefore more readily accessible for the purpose of removing it. This easy accessibility of the burr makes it possible to carry out removal by galvanic (electrochemical) action or by abrasion. A sand blasting procedure could also be used because deburring is considerably less critical with the present nozzles than for previously known nozzles.

A further advantage of the invention resides in the fact that the recess which forms the air circulation zone adjacent the jet simultaneously protects the outer periphery of the nozzle does not of necessity have to be formed by milling or grinding but can also be formed through turning because the characteristics of the nozzle of the invention are no longer dependent on the accuracy of intersecting curves. Small differences in the bored, milled, ground or turned depth can be accommodated because these differences have practically no influence in the size and shape of the nozzle opening.

Furthermore, it is advantageous that the punch used for carrying out the punch or stamping procedure and for which a high accuracy is naturally required can be reground without problem because the section of the punch over its entire length is exactly predetermined and constant and during the regrind procedure solely the cutting edges must be resharpened by grinding at right angles to the longitudinal axis of the punch.

Also, according to the invention there is provided a nozzle produced by the method as aforesaid.

The invention will now be more particularly explained by way of example only embodiment and with reference to the drawing; in the drawings are shown: Fig. 1 is a schematic partly sectioned side view to an enlarged scale of discharge nozzle, Fig. 2 a view on the end face of the nozzle of Fig. 1 and illustrating two alternative crosssections of a discharge passage to either side of a horizontal datum, Fig. 3 a sectioned illustration to an enlarged scale of the detail A of Fig. 1, and showing in addition a punch partially located within the nozzle body, and Fig. 4, 5, 6 illustrate alternative sections for the punch as seen on the line IV-IV of Fig. 3.

A nozzle body is produced from a metal blank and in its form and shape is externally similar to customary discharge nozzles. It has a circular sectioned supply passage 2 which is manufactured by boring and which passes without steps into a discharge passage 3 produced, in accordance with the invention, by a punch- ing procedure. A recess 4 is produced in the end face of the nozzle body 1 before the formation of the discharge passage, and follows the discharge passage 3, and on the one hand serves to protect the end face of the nozzle in particular by preventing contact of the nozzle end face with an object resulting in distortion of the discharge opening of the discharge passage, and on the other hand brings about a sideways air circulation adjacent the jet which ensures that the formation of drips of liquid, which is generally unacceptable, does not occur at the nozzle.

From the end face view of Fig. 2 it can be seen that the nozzle opening is preferably oval or at least substantially oval as shown above the horizontal datum at 11, and this crosssectional shape of the passage is activated by the choice of a punch of corresponding section.

Below the horizontal datum line in Fig. 2 there is illustrated an alternative circular crosssection 12 for the discharge passage which is produced using a punch of circular section.

The recess 4 which follows the passage section of the nozzle can be of stepped construction so that on the one hand there is provided a general protective recess 4 and on the other hand a groove 5 extends at least somewhat deeper into the material of the nozzle body for promoting the sideways circulation of air alongside the discharge. It is, however, essential that these subsequently formed recesses do not significantly affect th eshape of the nozzle discharge opening because this form is exclusively given by the punch or stamping operation.

The details view of Fig. 3 shows the area of the nozzle opening and allows it to be clearly recognized that the characteristics of the nozzle is given practically exclusively through the punching procedure which leads to the formation of the discharge passage 3 with walls 6 parallel to the nozzle axis. It will be especially noted that the discharge passage 3 is of finite length and that this length is generally chosen to be a few tenths of a millimeter e.g. 5 as measured axially along the wall 6.

Any trivial deviations in the depth of the bore or the tapered stepless transition region 7 brought about by wear of the tip of the boring tool result solely in a change of the axial length of the nozzle passage section which in practice will have no effect on the function efficiency and working life. In contrast the finite axial length of the discharge passage means that small amounts of wear occurring at the nozzle discharge opening, which in prior art nozzles would have resulted in reduced working life of the nozzle, can be tolerated because the jet is still constrained by the section of the discharge passage 3. The transition 8 from the bore 2 to the passage section 3 is maintained free of burrs through the punch procedure and the burr formed at the outside, i.e. at the transition from the passage section 3 to the recess 4 is easily accessible and can accordingly be removed inexpensively and without the danger of a change to the nozzle opening, typically by galvanic (electrochemical) action or by a deburring process of abrasive kind in which e.g.

the nozzle is shaken together with a number of small particles to abrade the burr.

The manufacturing procedure of the invention is suitable for all customary materials and the choice of a suitable punch makes possible the manufacture of the necessary shape of the opening in the nozzle. The detail of the cutting edge of the punch is not shown but can simply be sharpened to a conventional profile for a cutting punch. The punch 9 used for forming the passage is also illustrated in Fig. 3 and subse queerly also in Figs. 4, 5, 6. It will be seen that the punch 9 has a generally cylindrical body which is adapted to be a sliding fit in the supply passage 2 so that the supply passage acts as a guide for the punch during the punch ing operation. In this punching operation the nozzle body is held in a suitable support and a blow is applied to the punch along its axis.

The actual punch tip 10 of the punch is elon gated and can be of various desired, but constant cross-sections for example the oval 11, circular 12 or eight sided shape 13 shown in Fig. 6. Such shapes can be readily produced Fig. 6. Such shapes can be readily produced by grinding and can either be applied directly to the punch or can be separately applied to 9 as illustrated in dotted lines a 14. The tip 10 will be such however that its major crosssectional dimension will be smaller than that of the supply passage 2. The insert should mate firmly with the punch body e.g. at the conical recess so that punching forces are adequately transmitted to the insert. The insert can also be secured by brazing if desired. The force on the punch can be kept comparatively small because of the small finite axial length of the discharge passage. It will be appreciated that in the punching procedure the tip 10 passes through the metal wall between the supply passage and the recess to produce the discharge passage.

Further modifications can readily be made to the nozzle and its method of manufacture without departing from the present invention e.g. it will be readily appreciated that the recess 4 and if desired the recess 5 can be made cylindrical in form by a turning operation.

During the punching operation a surface finish is achieved for the surface of the wall bounding the discharge passage which is characteristic of the punching operation i.e. primarily very fine lines extending in the axial direction which are believed to beneficially affect the flow conditions through the discharge passage.

Whilst such discharge nozzles are customarily used for discharging water in air they could equally well be used for discharging other liquids in other gases.

WHAT WE CLAIM IS:- 1. A method of manufacturing a nozzle for discharging liquids at relatively high pressure, the method comprising the steps of: a) boring a supply passage of circular crossection into one end of a metal nozzle blank, whereby the end portion of said bored passage is continuously tapered without steps and terminates short of the end of the nozzle blank.

b) machining a recess into the opposite end of the blank and wherein, as a result of steps (a) and (b) there results a nozzle blank in which the said supply passage and the said recess are separated by a wall of metal, c) selecting a punch having an operative elongate tip of constant cross-section with a major cross-sectional dimension smaller than that of the supply passage and introducing the tip of the punch into the supply passage, d) punching the punch tip through the wall of metal between the supply passage and the recess whereby to produce a dis charge passage with parallel sides and a cross-section corresponding to that of said operative elongate tip and defining the pro file of the jet discharged from the nozzle, wherein the tapered end portion of said supply passage provides in operation an advantageously shaped flow guiding surface.

2. A method to claim 1, comprising the further steps of selecting a punch having a body portion of a diameter substantially equal to that of the supply passage, and guiding the punch by the supply passage during said punching operation.

3. A method according to claim 1 or 2, in which any burr formed the end face of the discharge passage is removed galvanically.

4. A method according to claim 1 or 2, in which any burr formed at the end face of the discharge passage by the punch operation is removed by an abrading operation.

5. A method according to any one of the preceding claims, in which the cross-section of said punch tip is oval.

6. A method according to any one of claims 1 to 4 in which the cross-setion of said punch tip is circular.

7. A method according to any one of claims 1 to 4, and in which said punch tip is of polygonal cross-section.

8. A method according to any one of the preceding claims, in which said recess is transverse groove across the end face of said nozzle blank.

9. A method of manufacturing a nozzle for discharging liquid at relatively high pressure, substantially as herein described with reference to and as illustrated in the accompanying drawings.

10. A nozzle for discharging liquids at relatively high pressure as made in accordance with any one of the preceding claims.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. e.g. it will be readily appreciated that the recess 4 and if desired the recess 5 can be made cylindrical in form by a turning operation. During the punching operation a surface finish is achieved for the surface of the wall bounding the discharge passage which is characteristic of the punching operation i.e. primarily very fine lines extending in the axial direction which are believed to beneficially affect the flow conditions through the discharge passage. Whilst such discharge nozzles are customarily used for discharging water in air they could equally well be used for discharging other liquids in other gases. WHAT WE CLAIM IS:-

1. A method of manufacturing a nozzle for discharging liquids at relatively high pressure, the method comprising the steps of: a) boring a supply passage of circular crossection into one end of a metal nozzle blank, whereby the end portion of said bored passage is continuously tapered without steps and terminates short of the end of the nozzle blank.