EP1781426B1 - Needle gun - Google Patents

Description

The present invention relates to a percussion device in the form of a needle gun comprising a cylinder housing in which a movable cylinder slidably supported between two compression springs, wherein in the cylinder, a flying piston reciprocates under the influence of compressed air and delivers a shock pulse to an anvil, on which under pressure from one of the two springs a needle carrier rests and wherein several needles axially slidably store in the needle carrier and rest under working pressure with their terminal needle heads on the anvil.

Impact devices of the type mentioned are widely used commercially under the name needle gun and have proven themselves many times in daily use. In principle, needle guns are used to clean surfaces, for example, to remove old paint residues or remove rust layers. The operation and construction of the needle guns leads to high material loads. Accordingly, one has often improved the impact devices of interest here in order to increase their service life.

In particular, to reduce the wear between the movable cylinder and the cylinder housing, a special sliding seal has been developed as known from EP-A-0'152'376. EP-A-0'152'376 thus discloses a striking device in the form a needle gun with the features of the preamble of claim 1.

An impact device of the type mentioned is also from the DE-U-84 32 499 known. In this document too, the main focus was on increasing the service life of the needle gun, this time focusing in particular on the wear problem between the anvil and the cylinder housing.

After years, the life of the above-mentioned impact devices has remained virtually unchanged, lately suddenly increased impact devices of the type mentioned have been complained of, as they have not reached the usual life. Although no changes have been made constructively, the above-mentioned complaints suddenly appeared. In tracing the offending devices, it has been found that these were mainly used during work in which high voltage pylons were de-rusted. The investigation has shown that the people working on the pylons use the impact device in continuous operation. The continuous operation is thereby realized in that the actuating button or the release lever was locked on the handle of the needle gun by means of adhesive tape, so that the needle gun when you release the same does not turn off the device. This, in turn, is related to the fact that the worker at the high-voltage mast practically has only one free hand and accordingly without having to reach around grab the needle gun immediately and work with it. For this purpose he has attached the needle gun to a safety rope, for example on a belt.

During normal de-rusting work, the worker pushes the needle gun onto the surface to be worked on, and the needles and their needle heads are directly adjacent to the anvil. If not worked, the needles hang in the needle carrier and the flying piston stands still, so that no Oscillation of the anvil takes place and the needles themselves are held unmoved in the needle carrier.

By the aforementioned continuous operation, in which, for example, the actuating lever is attached to the handle with adhesive tape, now the flying piston reciprocates even when not working and therefore the needles do not abut the anvil. Consequently, since the flying piston continues to deliver its pulses to the anvil, the vibration of the anvil is also transmitted to the needle carrier. Accordingly, the needle carrier, which is pressed by the compression spring 6 against the anvil, also oscillates. The vibration of the needle carrier causes the needles to vibrate practically unencumbered and thereby hit the anvil, which in turn provides the needles with a shock pulse. Accordingly, the needle carrier is now claimed by the needle heads on impact. The needle carrier which is usually made of plastic, is not designed for this type of impact load and is thereby destroyed after a relatively short time.

It is therefore an object of the present invention to improve a percussion device of the type mentioned in such a way that the life of the device is increased even in continuous use.

This object is achieved by a striking device having the features of patent claim 1.

First attempts to solve this problem by making the needle carrier made of metal, have proved to be unviable way. The relatively finely designed needle heads of the needles, which are made of hardened steel, have led very quickly to fatigue fractures. In particular, practically the needle heads were separated from the needles. In the solution according to the invention this problem has not surfaced.

Figur 1

eine erfindungsgemäss ausgerüstete Schlagvorrichtung in der Gestalt einer Nadelpistole in einem zentrischen Längsschnitt gesamthaft dargestellt

Figur 2

einen Diametralschnitt durch einen erfindungsgemäss ausgestalteten Nadelträger mit einer plattenförmigen Einlage, während in

Figur 3

eine becherförmige Einlage für sich allein dargestellt ist, während letztlich

Figur 4

gelöscht

Figur 5

einen Nadelträger zeigt, der lediglich als mehrlagige Lochplatte gestaltet ist, und einen Distanzring, der zwischen der Lochplatte und dem Amboss angeordnet wird.

In the following description, various embodiments of the inventive impact device are explained with reference to the accompanying drawings. It shows:

FIG. 1

an inventive equipped impact device in the form of a needle gun in a central longitudinal section shown in total

FIG. 2

a diametral section through an inventively designed needle carrier with a plate-shaped insert, while in

FIG. 3

a cup-shaped insert is shown on its own, while ultimately

FIG. 4

deleted

FIG. 5

shows a needle carrier which is designed only as a multi-layered perforated plate, and a spacer ring which is arranged between the perforated plate and the anvil.

The impact device shown here in the form of a needle gun corresponds in construction DE-U-84 32 499 or the corresponding CH-A-654 513 , Regarding the mode of action, reference is made to the content of these protective rights. The main component of the impact device forms a cylinder housing 1, which is substantially in the form of a Cylinder corresponds with circular cross section. In the cylinder housing 1, a movable cylinder 2 is slidably mounted and sealed by means of mechanical seals 19 relative to the cylinder housing 1. In the cylinder 2 superimposed a flying piston 3, which is provided with a thickened end which runs in a first pressure chamber D ₁ , while the opposite, slimmer end of the flying piston 3 is provided with a hammer-like head and in a second pressure chamber D. ₂ moves. The thickened piston end is denoted by 25, the slimmer, formed to a hammer head end of the piston 26. The flying piston 3, which is oscillated to and fro, hits on anvil 4, respectively. The anvil 4 has a steel core 40 and is coated with a thickened sliding ring 41 made of abrasion-resistant plastic. In Gleitring 41 more Druckluftentlastungsnuten 42 are formed in the axial direction. On the anvil 4 rests a needle carrier 5, which has an approximately cup-shaped shape in the embodiment shown here and on its special, inventive embodiment will be discussed below. The needle carrier 5 is pressed under the pressure of the compression spring 6 on the anvil 4 and this in turn on the cylinder 2. The compression spring 6 is supported in the cylinder housing 1 on a shoulder-shaped constriction 18 from. A compression spring 7 which is accommodated at the opposite end in the cylinder housing 1, is supported on a housing cover 9 and rests on the movable cylinder 2. The movable cylinder 2, or its first pressure chamber D ₁ is closed by means of a cylinder cover 8. The impact device shown here operates by means of compressed air, which is supplied by a handle 10 from a feed line 11. The handle 10 is formed by a handle tube 13 which communicates via an air inlet 12 in communicating connection with the cylinder housing 1 or with the pressure chamber D ₁ and indirectly with the second pressure chamber D ₂ . Via a connecting piece, the feed line 11 is connected to the handle tube 13. Over the handle tube 13, a handle sleeve 14 is slipped. In the connector, a valve 17 is arranged, which is manually actuated via an actuating lever 15. The actuating lever 15 is pivotable about the lever axis 16.

In the flying piston 3, a T-shaped bore 22 is mounted, which consists of a central axial bore 23 and a diametrical bore 24. Compressed air flows via the air inlet 12 into a circulating air supply chamber 27, which is formed in the movable cylinder and flows in through a bore in the movable cylinder 2. Here, the piston is pressed with its thickened piston end 25 in the direction of the cylinder cover 8 until the flying piston is displaced so far that the diametrical bore 24 communicates with the cylinder chamber on the air supply side, whereby through the central axial bore 23, the compressed air into the first pressure chamber D _first flows and moves the piston in the opposite direction, which abuts the anvil and the compressed air from the first pressure chamber D _{1 flows} into the second pressure chamber D ₂ via the T-shaped bore 22, wherein according to the anvil lifts from its seat on the movable cylinder 2 and the compressed air via the relief grooves 42, which are also present on the needle carrier 5, escapes. After the compressed air relief, the compression spring 6 pushes the needle carrier 5, the anvil 4 and thus the piston 3 back to the starting position and the cycle is repeated.

With respect to the inventive design of the needle carrier 5 is subsequently to the FIGS. 2 to 5 directed. The needle carrier 5 essentially has a guide plate 50 in which a plurality of needle guide bores 51 are formed. The needle guide bores 51 are regularly distributed over the surface of the circular guide plate 50. The distance between two adjacent needle guide holes 51 is selected so that the needle heads 21 of the needles 20 do not touch each other. Subsequent to the guide plate 50 is followed by an annular wall 52, which in the embodiments according to the Figures 2 and 4 is integrally connected to the needle guide plate 50. The annular wall 52 has a plurality of axially extending circumferentially evenly distributed Druckluftentlastungsnuten 53rd on. The annular wall 52 of the needle carrier 5 serves to support and guide the needle carrier 5 in the cylinder housing 1. Overall, therefore, the needle carrier 5 has a cup-shaped shape, the cup wall rests on the anvil, not shown here. Between the anvil and the guide plate 50 thus remains a cavity 54 which is peripherally bounded by the annular wall 52. In this cavity 54 are the needle heads 21 of the needles 20. If not worked with the impact device, the needles 20 are in the holes 51 so guided in the guide plate 50, that the needle heads within the cavity 54 loosely rest on the guide plate 50. When working with the device, the needles 20 are pressed onto a surface to be machined and the needle heads 21 abut against the anvil. Under the action of the flapping pulses of the flying piston, which are transmitted to the needles 20 via the anvil, the needles 20 are set into oscillating motion. In this case, however, they will normally perform this oscillating movement so that the needle heads do not come into contact with the guide plate 50 of the needle carrier 5. As mentioned above, however, this situation is different when the device operates unloaded. Now, the needles 20 are practically reciprocated over the entire height of the annular wall 52 and meet at a correspondingly high speed on the inner surface of the guide plate 50. In order to avoid corresponding damage to the needles 20 and the needle carrier 5, it is therefore proposed according to the invention to manufacture the needle carrier from at least two layers of material of different hardness. Of course, the layers should of course be arranged perpendicular to the direction of the needles. In the embodiment according to the FIG. 2 is, as already mentioned, the guide plate 50 with the therein needle guide holes 51 and the annular wall 52 made in one piece and molded, for example, from a plastic. Accordingly, the plastic bottom forms a first material layer 55, on which a second material layer 56 rests. This second material layer 56 is in the embodiment according to the FIG. 2 a metal plate having a hole corresponding to the needle guide holes 51. In principle, this second material layer 56 may be laid loosely.

To simplify the assembly, at least one position orientation bead 57 will be arranged on the inside of the annular wall 52 down to the guide plate 50 and the second material layer 56, which is here designed as a protective plate 58, provided with a correspondingly shaped bead. The second material layer 56, or the protective plate 58, can be made of different materials. This may either be a metal plate, preferably a softer material is used here than that from which the hardened needles 20 and their heads 21 are. In addition to relatively soft steel or iron alloys, there are also various non-ferrous metals and their alloys or aluminum. However, it is also possible to manufacture the protective plate 58 or the second material layer 56 of a particularly high-quality plastic, which is correspondingly wear-resistant and impact-resistant. Plastics from the group of PBO, PA or PE are particularly suitable for this purpose. In this case, therefore, both material layers 55 and 56 are made of plastic. In this case, it makes sense to manufacture the harder layer of a material having a hardness of more than 50 ° Shore A.

Instead of an inserted or glued-in protective plate 58, the second material layer 56 cup-shaped as a protective cup 59 may be designed as the FIG. 3 shows. The protective cup 59 can be formed and punched from any metal sheet. The protective cup is then positively and / or non-positively inserted into the needle carrier 5, of course, in turn, so that the holes cover the holes of the protective cup 59 itself.

Ultimately shows the FIG. 5 Yet another possibility for the design of the needle carrier 5. Here, the guide plate 50 is made as an actual plate, which is made of at least one respective first material layer 55 and a second material layer 56. These are, for example, multi-layer plates from which the guide plate 50 with the Needle guide holes 51 is punched out. The annular wall 52 is made separately in this case and consists of a cylindrical ring which may be made of plastic or metal and replaces the original annular wall 52. In this case, not only the choice of the material of the first material layer 55 and the second material layer 56 are freely combinable, but also the separately manufactured support ring 60 can be independently made of any material. Of course, one will of course make sure that material pairings come to conditions that cause the least possible material wear. Is the first material layer 55, which is loaded in the installed state in this case by the compression spring 6, made of a relatively soft plastic, so you will reasonably provide an intermediate ring, which comes to rest between the guide plate 50 and the compression spring 6.

In particular, the solution according to the FIG. 5 , in which practically the needle carrier 5 is designed in two parts, it also makes it possible to provide material layers which have a high elasticity, as a result of which the oscillation behavior of the needle gun can be influenced overall.

LIST OF REFERENCE NUMBERS

1

cylinder housing

2

movable cylinder

3

flying piston

4

anvil

5

needle carrier

6.7

compression springs

8th

cylinder cover

9

housing cover

10

Handle

11

feeder

12

air intake

13

handle tube

14

grip section

15

actuating lever

16

lever axis

17

Valve

18

shoulder-shaped constriction

19

Mechanical seal

20

needles

21

Nadelköpf

22

T-shaped bore

23

centric axial bore

24

diametrically hole

25

Thickened piston end

26

hammer head slender piston end

27

Air supply chamber

D ₁

first pressure chamber

D ₂

second pressure chamber

40

steel core

41

sliding ring

42

relief grooves

50

guide plate

51

Needle guide bores

52

ring wall

53

Druckluftentlastungsnuten

54

cavity

55

first material situation

56

second material situation

57

Orientierungswulst

58

protection plate

59

protective cup

60

support ring

Claims (11)

1. A hammer device in a form of a needle gun, comprising a cylinder housing (1) in which a movable cylinder (2) is slidably mounted between two compression springs (6, 7), a floating piston (3) being moved to and fro in the cylinder by compressed air, and delivers a hammer impulse onto an anvil (4) on which a needle carrier rests under a pressure of one of the two compression springs (6, 7), a plurality of needles (20) in the needle carrier (5) mounted in an axially sliding manner and under operating pressure bearing on the anvil (4) with the needle heads (21) at an end, and the needle carrier (5) comprising a cup with a guide plate (50), characterized in that the guide plate (50) is manufactured from at least two layers of material with different hardness or different wear-resistance, wherein the layers are arranged perpendicularly to a running direction of the needles (20) and the material layer of the guide plate (50) closest to the anvil consists of a harder or more wear-resistant material than the material layer which follows is in the axial direction of the needles.
2. The hammer device according to claim 1, characterized in that the material layer of the guide plate (50) closest to the anvil consists of more wear-resistant material than the material layer which follows in the axial direction of the needles.
3. The hammer device according to claim 1, characterized in that the needle carrier (5) is injection moulded from a plastic, and at least one material layer is formed as an inserted metal plate.
4. The hammer device according to claim 1, characterized in that the harder layer consists of metal.
5. The hammer device according to claim 1, characterized in that all layers are made from plastic, wherein the harder layer has a shore A hardness of more than 50.
6. The hammer device according to claim 2, characterized in that the material layer closest to the anvil is made from wear-resistant material made from plastic is selected from the group of PBO, PA and PE.
7. The hammer device according to claim 1, characterized in that the cup of the needle carrier (5) consists of two parts, namely a guide plate (50) consisting of at least two material layers (55, 56) and a support ring (60), made from any desired material, which is manufactured separately.
8. The hammer device according to claim 1, characterized in that the cup of the needle carrier (5) is manufactured in one piece, in that a peripheral annular wall (52) is integrally formed on the guide plate (50), the free end of which comes to rest on the anvil (4).
9. The hammer device according to claim 8, characterized in that the cup of the needle carrier (5) is injection moulded from plastic and a thin-walled protective cup (59) made from metal, fitting with a positive fit, is insertable therein and forms a second material layer (56).
10. The hammer device according to claim 8, characterized in that the cup of the needle carrier (5) forms a first material layer (55) and an inserted protective plate (58) forms a second material layer (56).
11. The hammer device according to claim 8, characterized in that the annular wall (52) has an orientation bead (57) which permits a positioned insertion of a protective cup (59) or a protective plate (58) into the needle carrier (5).

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