EP2505310B1 - Jet head - Google Patents

Description

• ein Strahlkopfgehäuse, das mit einer Strahlmittelzuführungsleitung und einer Luftzuführungsleitung zu verbinden ist, die in wenigstens einen Luftzuführungskanal übergeht;
• eine Strahldüse mit einer Düsenbohrung, deren im Strahlkopfgehäuse liegendes Ende mit einer Einlauföffnung versehen ist;
• ein mit der Strahlmittelzuführungsleitung zu verbindendes Strahlmittelzuführelement, dessen Längsachse mit der Längsachse der Strahldüse fluchtet und das mit einer Strahlmittelzuführdüsenspitze vor der Einlauföffnung der Strahldüse mündet,
• ein Käfigelement mit wenigstens einer Luftdurchtrittsöffnung, das das Strahlmittelzuführelement umgibt und das in einer Aufnahmebohrung des Gehäuses gelagert ist, in welcher der Luftzuführungskanal mündet, wobei eine vordere Trichterringscheibe des Käfigelements eine kegeltrichterförmige Öffnung aufweist, in welche hinein sich eine kegelförmige Strahlmittelzuführdüsenspitze des Strahlmittelzuführelements erstreckt, wobei zwischen dem Innendurchmesser der vorderen Trichterringscheibe und dem Außendurchmesser des Strahlmittelzuführelements ein innerer, kegelmantelförmiger Ringspalt ausgebildet ist.

The invention relates to a jet head for emitting a blasting medium in a compressed air stream, comprising at least

• a blast head housing to be connected to a blast medium supply line and an air supply line, which merges into at least one air supply duct;
• a jet nozzle with a nozzle bore whose end located in the jet head housing is provided with an inlet opening;
• a Strahlmittelzuführelement to be connected to the Strahlmittelzuführungsleitung whose longitudinal axis is aligned with the longitudinal axis of the jet nozzle and which opens with a Strahlmittelzuführdüsenspitze in front of the inlet opening of the jet nozzle,
• a cage member having at least one air passage opening surrounding the Strahlmittelzuführelement and which is mounted in a receiving bore of the housing, in which the air supply channel opens, wherein a front funnel ring pulley of the cage element a conical funnel-shaped opening into which extends a conical Strahlmittelzuführdüsenspitze the Strahlmittelzuführelements, wherein between the inner diameter of the front hopper ring disk and the outer diameter of the Strahlmittelzuführelements an inner, cone-shaped annular gap is formed.

Blasting heads serve to supply blasting media, mix with compressed air, and then expel the mixture through the nozzle bore at high speed to machine a workpiece surface.

At one in the DE 201 06 816 U1 disclosed jet head, the blasting agent supply is carried out by a Strahlmittelzuführelement which is in alignment with the nozzle bore. The blasting agent supply element opens into a mixing chamber in the housing. Compressed air is injected laterally into the mixing chamber, tears the blasting agent into the funnel-shaped inlet opening of the blasting nozzle and leaves the blasting head through the nozzle bore again. The area of the mixing chamber is very susceptible to wear, since whirling, mostly abrasive particles wear both the funnel-shaped inlet opening of the nozzle bore as well as the conically tapered tip of the Strahlmittelzuführelements.

With increasing wear, the gap width and the gap shape between the cone tip and funnel mouth change, which in turn changes the flow conditions of the jet head as the operating time increases. An adjustment of the gap is time consuming and can over it In addition, it can not be verified by measuring instruments, as there is no insight into the chamber. When dismantling the blasting abrasive nozzle, the nozzle element with funnel bore and the blasting agent feed element with cone tip must be removed separately. Outside the case, however, their position relative to one another can not be exactly set and checked. The setting of the abrasive nozzle can therefore be made only empirically by the operator.

A generic jet head is in the DE 20 2008 016 923 U1 disclosed. The fact that in this jet head the Strahlmittelzuführelement is inserted into a cage member which is mounted in a receiving bore, in which in turn the air supply channel opens, and in that in a shell of the cage element at least one air passage opening is introduced, is between the inner diameter of a funnel ring on Cage element and the outer diameter of the Strahlmittelzuführelements formed a geometrically well-defined, inner annular gap, which determines the formation of the air flow and thus determines a constant mixture of air and blasting agent.

The directed air flow is thus already effected on the jacket of the blasting agent feed element and not only in the area of its mouth. The air flow can thus form stabilized and then move along the outer periphery of the Strahlmittelzuführelements before it enters the inner chamber within the anti-wear jet nozzle, where the mixing with the blasting agent takes place. Irregularities in the annular gap, be they caused by local wear at certain angular positions or by a total change in the width of the air gap caused by wear, either lead to the collapse of the pneumatic conveying of the blasting agent, because the air flow is not strong enough to entrain and accelerate a lot of blasting agent , or to excessive wear in the area between Strahlmittelzuführdüsenspitze and inlet mouth of the actual jet nozzle, because too much blasting medium is sucked. The remedy, however, only the exchange of worn parts, ie in particular the Strahlmittelzuführelements, at the top and inner bore, the strongest signs of wear during operation, because the Strahlmittelzuführelement zoom out in the blasting agent immediately after passing the leading edge of the Strahlmittelzuführdüsenspitze in the through the inlet funnel of the nozzle formed chamber and bounces in particular against the thin edge portion of the tip. Since anyway only Strahlmittelzuführelemente made of hardened metallic or ceramic materials, especially hard metals, have a sufficient life, the frequent replacement of the Strahlmittelzuführelements is very expensive. However, if the replacement is delayed due to cost reasons, all other parts adjacent to the mixing chamber between the blasting agent feed nozzle tip and the inlet funnel of the nozzle are also massively worn down, up to the destruction of the housing.

The object of the invention is thus to enable a cost-effective operation of the jet head.

This object is achieved by a jet head with the features of claim 1.

The outer sleeve thus does not come into contact with the blasting agent, as long as the inner sleeve is not completely destroyed. Due to the fact that the conical tip of the outer sleeve, viewed in the flow direction, extends further forward over the funnel-ring disk of the cage element, those parts which define the annular gap which is decisive for the air flow are wear-resistant and geometrically precisely fixed relative to one another.

The inner sleeve is in the outer sleeve and extends in length to beyond the outer sleeve also forward. As a result, the conical tip of the inner sleeve and the conical tip of the outer sleeve can form a common tip of the Strahlungsmittelzuführelements, which is also tapered. In particular, the partial tips of the sleeves have identical cone angles of 15 'to 50 °, so that a uniform conical surface is formed at the tip of the Strahlmittelzuführelements.

"Conic" in the context of this invention, concave and convex geometries, each in the form of a present telflächen. However, this also includes spherically curved lateral surfaces, ie spherical sections in the strict geometric sense.

In the blasting head according to the invention wear occurs in operation predominantly on the leading edge of the tip of the inner sleeve, where the blasting agent from the inner bore of the Strahlmittelzuführelements occurs and to the side into the mixing chamber in the region of the inlet opening of the jet nozzle, as well as on the inner bore itself ,

If the inner sleeve worn, it can be easily replaced according to the invention. For this purpose, the inner sleeve can be formed very inexpensively from plastics. In particular, it has been shown that the wear in highly abrasive blasting agents such as corundum can be reduced by the use of rubber-elastic materials, in particular of elastic polyurethane casting resins with a hardness of about 40 to 90 Shore A, because this energy impinging abrasive particles elastically absorb and thereby reduce the abrasion of the material surface.

• Bei der Verwendung weichelastischer Werkstoffe kann der Bund die Funktion einer Dichtscheibe erfüllen.
• In jedem Fall überdeckt der Bund die rückwärtige Stirnseite der Außenhülse und schützt sie vor auftreffendem Strahlmittel, insbesondere wenn am Übergang von der Strahlmittelzuführungsleitung zum Strahlmittelzuführelement ein Durchmessersprung besteht.

The replacement can be done simply by the inner sleeve, the Strahlmittelzuführelement is pulled out after removing the Strahlmittezuführungsleitung backwards. The inner sleeve preferably has a collar at this end, which not only facilitates removal from the outer sleeve, but also offers further advantages:

• When soft elastic materials are used, the collar can fulfill the function of a sealing washer.
• In any case, the collar covers the rear face of the outer sleeve and protects it from impinging Blasting means, in particular when there is a diameter jump at the transition from the blasting agent supply line to the blasting medium feed element.

It is also possible to design the inner sleeve so that it can be pushed further forward when worn. The conical shape can then be recut in the case of inner sleeves made of plastic by the user himself.

For very thin cylindrical inner sleeves, it may not even be necessary to provide these at their end with a conical shape. It is sufficient that the inner sleeve protrudes slightly beyond the front edge of the outer sleeve in order to protect it.

It is also possible to provide at the front end a cone-shaped collar, which lays in front of the front side of the outer sleeve and this protects very well against wear.

It is essential in all embodiments of the inner and outer sleeve only that the outer sleeve has at least one cone-shaped portion which extends in the axial direction to the funnel ring disk. Thus, the annular gap is always defined exactly, no matter how in the following axial end portion of the state of wear of the subsequent tip region. Although it is advantageous for the flow, if there is a continuous, transition-free cone sheath at the entire tip. Decisive, however, is the rear part at the annular gap, whereas deviations ahead are less significant.

Depending on the type of blasting agent and depending on the other economic considerations, inner sleeves made of hard metal, in particular boron carbide, in the same outer sleeve of the blasting head according to the invention can be used. Although their costs are more expensive to manufacture by a factor of 100 to 1000 than an inner sleeve made of thermoplastic or cast resin, however, the higher material price can be amortized by the fact that the use of high-strength materials longer service life can be achieved and thus lower set-up and assembly times , just when the blasting head according to the invention is fixedly installed in hard to reach areas of a system or if the exchange is possible only under certain protective measures for the staff, etc.

The user is therefore free in the assembly of the blasting head and need not hold different blasting heads for different purposes and locations, but he can provide them with the most economical for his own purposes type of inner sleeve.

The fine annular gap forms the decisive flow obstacle, via which the amount of air for the operation of the jet head and the flow velocity can be adjusted. The annular gap can be structurally simple and can be measured during maintenance, because the Strahlmittelzuführelement can also be used outside of the housing in the cage element. Thus, due to axial fixed stops, the two parts assume the same relative position to one another during the test as they do when installed inside the housing.

It is advantageous if the front funnel ring disk can be inserted into the cage element. The funnel ring disc can be made much easier and more accurate as a single part than in a one-piece design of the cage element. In the event of wear, the funnel washer can be easily replaced without the need for manual adjustment or control of the vacuum applied during operation

It can also funnel ring discs are provided with different axial Abmäßen to adjust the ring gap by selecting a funnel ring disk.

It is preferably provided to manufacture a uniform funnel-ring disk and to arrange at least one spacer ring between it and the cage element, so as to move the conical surface forward or backward in the axial direction and thus make the annular gap narrower or wider.

Preferably, the cage member, the Strahlmittelzuführelement and the jet nozzle from the same side of the holes in the housing are insertable, in this order. The support of cage element and Strahlmittelzuführelement takes place at a bearing shoulder on the rear side of the housing, which encloses a bore through which protrude parts of the Strahlmittelzuführelement. The interior of the housing can be easily drilled and turned out. Because of the fixed positional sales need no cover, flanges or the like to support the internal components are mounted at the rear end of the housing.

The Strahlmittelzuführelement should have a collar which rests against a fixed bearing on the jet head housing. Thus, the axial position of the Strahlmittelzuführelement is set within the housing and also relative to the cage element.

The invention will be explained in more detail below with reference to embodiments of a jet head according to the invention and with reference to the drawing.

Fig. 1

einen montierten Strahlkopf im Schnitt;

Fig. 2

ein Detail des Strahlkopfes aus Figur 1;

Fig. 3

Teile des Strahlkopfes in Explosionsdarstellung und

Fig. 4

Teile einer weiteren Ausführungsform eines Strahlmittelzuführelements.

The figures show in detail:

Fig. 1

a mounted jet head in section;

Fig. 2

a detail of the blasting head FIG. 1 ;

Fig. 3

Parts of the jet head in exploded view and

Fig. 4

Parts of another embodiment of a Strahlmittelzuführelements.

FIG. 1 shows a blasting head 100, which consists essentially of a housing 10, a jet nozzle 20, a Strahlmittelzuführelement 30 and a cage member 50.

On the housing 10 is in the rear d. H. remote from the jet nozzle 20 region, a shoulder 18 formed as a fixed bearing on which the Strahlmittelzuführelement 30 is applied. From behind, an adapter element 62 of a blasting agent supply line 60 with a union nut 61 is screwed onto a thread 32 on the blasting medium feed element 30.

The part of the blasting agent feed element 30 located inside the housing 10 is received in a cage element 50. This has at the front end a funnel ring disk 54, through which a Strahlmittelzuführdüsenspitze 31 of the Strahlmittelzuführelements 30 protrudes forward into a mixing chamber, the formed within a conical inlet opening 24 of the jet nozzle 20, since there the air flow introduced via an air supply line 40 into the housing 10 and the blasting agent are mixed.

The nozzle bore 21 opens at an orifice 22. The jet nozzle 20 is screwed into the housing 10 from the front. Compared to the cage member 50, the seal via a ring seal.

The blasting agent feed element 30 is formed by an outer sleeve 35 and an inner sleeve 36 inserted therein. Both together form at the in FIG. 1 left end of a conical Strahlmittelzuführdüsenspitze 31 from. Approximately in the middle of the length, a collar 33 is integrally formed on the outer sleeve in order to determine the position of the Strahlmittelzuführelements 30 in the housing 10 exactly.

The cage member 50 has end annular discs, of which at least the left is removable and has at its periphery the shape of a cone-shaped funnel whose cone angle coincides with the cone angle of the Strahlmittelzuführdüsenspitze 31, in particular the enlarged view in FIG FIG. 2 shows. This forms an exact annular gap between the Strahlmittelzuführdüsenspitze 31 and the funnel ring disk 54, wherein the annular gap over its entire axial length also has the same gap width and thus neither rejuvenated nor widening. The further advantage is that blasting agent does not protrude to the cage element 50 even with complete wear.

The dash-dotted vertical line in FIG. 2 marks the plane of the leading edge of the conical tip 35.1 on the outer sleeve 35. It is clearly visible that this ends in the flow direction in front of the end face of the funnel ring disk 54.

In the housing, a receiving bore is provided to receive the cage member 50. In the area of the receiving bore in the housing, the air supply channel 11 also opens.

FIG. 3 shows the essential parts of the blasting head 100 in an exploded view capable of each other before assembly. The inner sleeve has a rear collar 36.2 to set the axial position relative to the outer sleeve 36 after insertion.

The funnel pulley 54 is inserted into the cage member 50 and therefore can be replaced in case of wear, but also to vary by differently shaped funnel ring discs position and width of the air gap.

FIG. 4 shows an alternative trained Strahlmittelzuführdüsenspitze 31 'of a Strahlmittelzuführelements in section. A conical tip 35.1 'of an outer sleeve 35', in turn, extends beyond the annular gap 52 formed with the funnel ring disk 54 to the front. Different from the embodiment described above, the conical tip region 36.1 'of an inner sleeve 36' is formed on a collar 36.2 ', which covers an end face 35.2' of the outer sleeve 35 'and protects against wear.

• Am Adapterelement 60 wird eine Strahlmittelzuführungsleitung 40 angeschlossen, über die ein Strahlmittel, wie beispielsweise Korund, angesaugt werden kann. Unten am Gehäuse 10 wird die Luftzuführungsleitung 40 an eine Druckluftquelle angeschlossen. Sobald der Luftstrom freigegeben ist, strömt Druckluft über den Luftzuführungskanal 11 und von dort in den äußeren Ringspalt 55, anschließend durch die Luftdurchtrittsöffnungen 51 des Käfigelements 50, durch den inneren Ringkanal 53 bis in den Ringspalt 52 zwischen der Trichterringscheibe 54 vorn am Käfigelement 50 und der kegelförmig ausgebildeten Strahlmittelzuführdüsenspitze 31 des Strahlmittelzuführelements 30. Außerdem liegt die kegelförmig ausgebildeten Strahlmittelzuführdüsenspitze 31 der Trichteröffnung 24 der Strahldüse 20 gegenüber, sodass dort ein abgeschrägter Luftkanal ausgebildet ist, durch welchen die Luftströmung in die Düsenbohrung 21 geleitet wird.

The function of the jet head 100 will be described with reference to FIG FIG. 1 explained again:

• On the adapter element 60, a blasting agent supply line 40 is connected, via which a blasting agent, such as corundum, can be sucked. At the bottom of the housing 10, the air supply line 40 is connected to a compressed air source. Once the air flow is released, compressed air flows through the air supply passage 11 and from there into the outer annular gap 55, then through the air passage openings 51 of the cage member 50, through the inner annular channel 53 into the annular gap 52 between the funnel washer 54 front of the cage member 50 and the In addition, the cone-shaped Strahlmittelzuführdüsenspitze 31 of the funnel opening 24 of the jet nozzle 20 is opposite, so that there formed a beveled air passage through which the air flow is passed into the nozzle bore 21.

The overpressure in the region of the inlet opening 24 results in a lower pressure being applied in the blasting medium feed element 30, and thus blasting agent is being drawn in via the blasting medium feed line. The blasting agent is then swirled within the mixing chamber formed in the funnel opening 24 inside the blasting head 100 and passes through the nozzle bore 21 to the mouth 22.

Claims (10)

1. Blasting head (100) for emitting a blasting agent in a compressed air stream, at least comprising:

   - a blasting head housing (10), which is to be connected to a blasting agent feed line (60) and to an air feed line (40) which merges into at least one air feed duct (11);

   - a blasting nozzle (20) having a nozzle bore (21), that end of which which lies in the blasting head housing (10) is provided with an inlet opening (24);

   - a blasting agent feed element (30), which is to be connected to the blasting agent feed line, the longitudinal axis of which is aligned with the longitudinal axis of the blasting nozzle (20), and which opens out with a blasting agent feed nozzle tip (31) upstream of the inlet opening (24) of the blasting nozzle (20);

   - a cage element (50) having at least one air passage opening (51), which surrounds the blasting agent feed element (30) and which is mounted in a reception bore of the housing (10), in which the air feed duct (11) opens out,

   wherein a front funnel annular disc (54) of the cage element (50) has an opening shaped like a conical funnel, into which a conical blasting agent feed nozzle tip (31; 31') of the blasting agent feed element (30) extends, wherein an inner annular gap (52) shaped like a cone shell is formed between the internal diameter of the front funnel annular disc (54) and the external diameter of the blasting agent feed element (30),
   characterized

   - in that the blasting agent feed element (30) comprises a metallic or ceramic outer sleeve (35; 35') with a tip (35.1; 35.1') which is shaped like a cone section at least in certain regions, and an inner sleeve (36; 36'), loosely inserted therein, with a tip (36.1; 36.1'), which tips (35.1, 36.1; 35.1', 36.1') have the same taper angle and form the blasting agent feed nozzle tip (31; 31');

   - in that the front edge of the cone-section-shaped region of the tip (35.1; 35.1') of the outer sleeve (35; 35') extends up to the funnel annular disc (54), as seen in the blasting direction, wherein only the cone-section-shaped tip (35.1; 35.1') of the outer sleeve (35, 35') lies opposite the funnel annular disc (54), and wherein the tip (36.1; 36.1') of the inner sleeve (36; 36') lies freely in the inlet opening (24) of the blasting nozzle (20).
2. Blasting head (100) according to Claim 1, characterized in that a cone-section-shaped collar (36.2') is formed at the front end of the inner sleeve (36') and covers the end face (35.2') of the outer sleeve (35').
3. Blasting head (100) according to Claim 1 or 2, characterized in that the taper angle is between 15° and 50°.
4. Blasting head (100) according to one of Claims 1 to 3, characterized in that the inner sleeve (36; 36') consists of cemented carbide, in particular of boron carbide.
5. Blasting head (100) according to one of Claims 1 to 3, characterized in that the inner sleeve (36; 36') consists of a soft-rubber-like material, in particular of an elastomeric polyurethane casting resin having a hardness of 40 ... 90 Shore A.
6. Blasting head (100) according to one of Claims 1 to 5, characterized in that the inner sleeve (36; 36') extends over the entire length of the outer sleeve (35; 35') and, at at least one end, has a diameter enlarged by a collar (36.2, 36.2').
7. Blasting head (100) according to one of Claims 1 to 5, characterized in that the front funnel annular disc (54) can be inserted into the cage element (50).
8. Blasting head (100) according to Claim 6, characterized in that at least one spacer ring is arranged between the front funnel annular disc (54) and the cage element (50).
9. Blasting head (100) according to one of the preceding claims, characterized in that the cage element (50), the blasting agent feed element (30) and the blasting nozzle (20) can be introduced into the housing bore from the same side of the housing (10).
10. Blasting head (100) according to one of the preceding claims, characterized in that the blasting agent feed element (30) has a collar (33), which bears against a locating bearing (18) on the blasting head housing (10).

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