CN212683857U - Pneumatic impact tool and piston for a pneumatic impact tool - Google Patents
Pneumatic impact tool and piston for a pneumatic impact tool Download PDFInfo
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- CN212683857U CN212683857U CN201922321381.4U CN201922321381U CN212683857U CN 212683857 U CN212683857 U CN 212683857U CN 201922321381 U CN201922321381 U CN 201922321381U CN 212683857 U CN212683857 U CN 212683857U
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Abstract
The present invention relates to a pneumatic impact tool and a piston for a pneumatic impact tool, the piston for an impact tool/pneumatic impact tool being adapted to be arranged in the tool for transferring impact energy to a working implement of the tool, and comprising a piston rod (10) and a large diameter portion/sleeve (20), the piston rod (10) having an elongated substantially cylindrical shape, a first end portion (10a) of the piston rod being adapted to impact an impact element of the tool for transferring impact energy to the working implement, the large diameter portion/sleeve (20) being arranged adjacent to the first end portion on the piston shaft, said portion having the shape of a hollow cylinder. Wherein the large diameter portion is made of a first material and the rod is made of a second material, the density of the first material being less than or equal to half the density of the second material. The utility model discloses still relate to one kind and include the power tool of piston. An improved piston with an optimized design is thereby provided.
Description
Technical Field
The present invention relates generally to pneumatic impact tools, also known as percussive tools. More particularly, the present invention relates to a piston adapted to be disposed in such a tool.
Background
Pneumatic impact tools, for example for material removal (including for example so-called chippers, chisels or impact hammers), are known, for example, for material removal. Such tools (also known as impact tools, impact tools and pneumatic impact tools-all terms being used interchangeably throughout this specification) typically include a piston that is reciprocated in a cylinder of the tool by compressed air (which is allowed to flow through an inlet and an outlet of the cylinder) and which is provided to impact a tool accessory (e.g. a hammer).
Such a piston design is designed to meet the following requirements: sufficient energy must be delivered to the tool attachment to provide effective and rapid material removal. To ensure this, a certain piston speed and an optimized pulse wave performance are required.
It is well known that the weight of the piston has a great influence on the dynamic properties of the piston, both in terms of the frequency of the impact and in terms of the achievable impact velocity. On the other hand, pulsed wave performance depends on the speed of propagation of the wave through the piston and the length of the piston. However, the conceivable range of piston sizes is mainly determined by factors such as the size of the tool and the possible arrangement of air inlets and outlets in the tool, which limit the design and size and thus the weight of the piston.
Since the dynamic performance of the piston is caused by a complex interaction between these factors and other related factors that need to be balanced to achieve the desired optimum impact performance, improvements are needed in the art of designing pistons for impact tools.
SUMMERY OF THE UTILITY MODEL
It is desirable to provide an improved piston for an impact tool having an optimized design. In particular, it is desirable to provide a piston that provides improved dynamic properties, allowing for optimized wave propagation. To better address one or more of these concerns, a piston and power tool as defined in the independent claims are provided, with preferred embodiments defined in the dependent claims.
According to a first aspect of the present invention, there is provided a piston for an impact tool, the piston being adapted to be arranged in the tool to transfer impact energy to a working implement of the tool, and comprising: a piston rod having an elongated substantially cylindrical shape, wherein a first end of the piston rod is adapted to impact an impact element of the tool for transferring impact energy to the working implement, and a large diameter portion arranged on the piston rod adjacent to the first end, the large diameter portion having the shape of a hollow cylinder, wherein the large diameter portion is made of a first material and the piston rod is made of a second material, the density of the first material being less than or equal to half the density of the second material.
According to a first aspect, the piston provides an inventive solution to the above-mentioned problem by a design comprising a plurality of parts including a rod and a large diameter part or sleeve, in this case made of a lighter material than the rod. The overall weight of the piston is thus reduced while the uniform design of the central portion of the piston (i.e. the shaft) remains unchanged, thereby achieving a lower weight while not affecting the propagation of waves through the shaft portion. Since the material weight of the large-diameter portion is light, a greater degree of freedom in design can be achieved. Furthermore, the material of the shaft may be chosen not on the basis of weight but on the basis of other important aspects, such as strength and durability of the piston.
The large diameter portion may be, for example, a bushing provided on the shaft by press fitting or shrink fitting or the like.
According to one embodiment, the density of the first material is less than or equal to 35% of the density of the second material. For example, according to one embodiment, the first material is a plastic material and the second material is steel. According to one embodiment, the first material is Polyoxymethylene (POM) and the second material is steel.
According to one embodiment, the first material is aluminum and the second material is steel.
According to one embodiment, the outer diameter of the large diameter portion is at least 1.5 times the diameter of the rod. According to one embodiment, the piston rod further comprises a radially protruding collar against which the large diameter portion abuts, wherein the outer diameter of the collar is equal to the outer diameter of the large diameter portion at the first end abutting the collar.
According to one embodiment, the radial thickness of the large diameter portion is less than or equal to 40% of the total length of the large diameter portion, preferably less than or equal to 30% of the total length of the large diameter portion. In one embodiment, the radial thickness of the large diameter portion is in the range of 12 to 20mm, preferably 13 to 17 mm. According to one embodiment, the weight of the large diameter portion is less than or equal to 15% of the weight of the rod. According to one embodiment, the length of the large diameter portion is less than or equal to 40% of the total length of the rod, preferably less than or equal to 30% of the total length of the rod.
According to one embodiment, the piston rod includes a groove provided at a position slightly lower than the second end of the large diameter portion. According to one embodiment, the piston rod has a length in the range of 50-100mm and the rod has a diameter in the range of 5-15 mm.
By adjusting the choice of material (the relation between stiffness and density) the additional advantage is obtained that the speed of sound and the speed of propagation of longitudinal waves in the piston due to impact are substantially the same in both materials. Thus, a coordinated pulse or wave can be achieved.
For example, according to one embodiment, the definition in the first material is
Is within +/-20% of the speed of sound in the second material (i.e., the longitudinal wave propagation speed, also referred to as the longitudinal elastic wave speed). According to one embodiment, the speed of sound c in the first material is within +/-10% of the speed of sound in the second material. In one embodiment, the speed of sound in the first material is even closer to the speed of sound in the second material, e.g., the speeds of sound may be substantially the same. One embodiment is where the first material is aluminum and the second material is steel, where the speed of sound between the two materials differs by about 5%.
According to one embodiment, the speed of sound c in the first material as described above is less than or equal to half the speed of sound in the second material. Thus, two consecutive pulses or waves can be realized. One embodiment relates to a tin brass/steel combination where the wave velocity in brass is about 65% of the wave velocity in steel, and another embodiment relates to a plastic/steel combination where there is a greater difference between the individual speeds of sound.
According to a second aspect of the present invention, there is provided a pneumatic impact tool comprising a piston according to any of the embodiments described above.
Thus, the piston for percussive tools of the present invention has an optimized design, in particular, the piston of the present invention provides improved dynamic properties and allows optimized wave propagation.
Objects, advantages and features of the power tool that are contemplated within the scope of the second aspect of the present invention will be readily appreciated from the foregoing discussion with reference to the first aspect of the present invention.
Further objects, features and advantages of the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art realize that different features of the present invention can be combined to form embodiments other than those described in the following.
Drawings
The invention is described below by way of illustrative and non-limiting detailed description of exemplary embodiments with reference to the accompanying drawings, in which
Fig. 1 is a perspective view of an exemplary piston according to one embodiment.
Fig. 2 is a perspective view of a shaft of an exemplary piston according to one embodiment.
FIG. 3 is a perspective view of an increased diameter portion of an exemplary piston, according to one embodiment.
All the figures are schematic, not necessarily to scale and generally show only parts which are necessary for the elucidation of the invention, other parts being omitted or simply mentioned.
Detailed Description
Fig. 1 shows an exemplary piston 1 arranged in an impact tool, said piston comprising a piston rod 10 and a large diameter portion 20 arranged adjacent to a first end 10a of said piston shaft.
The rod (or shaft) 10 is shown in more detail in fig. 2 and is in the shape of an elongated cylinder having a length L10 and a diameter D10. The first end 10a of the rod 10 is adapted to impact an impact element of the impact tool, such as an intermediate piston or a work implement, for delivering impact energy.
The piston shaft further comprises a radially projecting collar 11 against which the large diameter portion 20 abuts, an outer diameter D11 of the collar being substantially equal to the outer diameter of the large diameter portion at its first end 20a abutting said collar, and a groove 12 provided at a position slightly lower than the large diameter portion 20, as shown in fig. 1.
Fig. 3 shows the large diameter portion 20 in more detail, which may also be referred to as the sleeve 20 or the sleeve 20. This part has the shape of a hollow cylinder formed by an outer diameter D20oAnd an inner diameter D20iIs defined, and thus has an outer diameter D20oAnd an inner diameter D20iA radial thickness defined therebetween. In the embodiment shown, the sleeve 20 extends over about 30% of the length of the shaft 10.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the present invention is not limited to the disclosed embodiments. Those skilled in the art will appreciate that many modifications, variations and substitutions are possible within the scope defined in the appended claims. In addition, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims shall not be construed as limiting the scope of the claims.
Claims (17)
1. A piston (1) for a pneumatic impact tool, characterized in that the piston is adapted to be arranged in the tool for transferring impact energy to a working implement of the tool and comprises:
a piston rod (10), the piston rod (10) having an elongated cylindrical shape, wherein a first end (10a) of the piston rod is adapted to impact an impact element of the tool for transferring impact energy to the work implement, and
a large diameter portion (20), the large diameter portion (20) being provided on the piston rod (10) adjacent to the first end, the large diameter portion having a hollow cylindrical shape,
wherein the large diameter portion is made of a first material and the piston rod (10) is made of a second material, the density of the first material being less than or equal to half the density of the second material.
2. A piston (1) for a pneumatic impact tool according to claim 1, characterized in that the density of the first material is less than or equal to 35% of the density of the second material.
3. A piston (1) for a pneumatic impact tool according to claim 2, characterized in that said first material is a plastic material and wherein said second material is steel.
4. A piston (1) for a pneumatic impact tool according to claim 3, characterized in that said first material is polyoxymethylene and wherein said second material is steel.
5. A piston (1) for a pneumatic impact tool according to claim 2, characterized in that said first material is aluminium and wherein said second material is steel.
6. The piston (1) for a pneumatic impact tool according to claim 1, characterized in that the outer diameter (D20) of the large-diameter portion is at least 1.5 times the diameter (D10) of the piston rod.
7. The piston (1) for a pneumatic impact tool according to claim 1, wherein said piston rod further comprises a radially protruding collar (11), said large diameter portion abutting against said collar (11), and wherein an outer diameter (D11) of said collar is equal to an outer diameter of said large diameter portion at a first end (20a) abutting against said collar.
8. The piston (1) for a pneumatic impact tool according to claim 1, characterized in that the radial thickness of the large diameter portion is less than or equal to 40% of the total length of the large diameter portion.
9. The piston (1) for a pneumatic impact tool according to claim 8, characterized in that the radial thickness of the large diameter portion is less than or equal to 30% of the total length of the large diameter portion.
10. The piston (1) for a pneumatic impact tool according to claim 1, characterized in that the weight of the large diameter portion is less than or equal to 15% of the weight of the piston rod.
11. The piston (1) for a pneumatic impact tool according to claim 1, characterized in that the length (L20) of the large diameter portion is less than or equal to 40% of the total length of the piston rod.
12. The piston (1) for a pneumatic impact tool according to claim 11, characterized in that the length (L20) of the large diameter portion is less than or equal to 30% of the total length of the piston rod.
13. Piston (1) for a pneumatic impact tool according to claim 1, characterized in that the length (L10) of the piston rod is in the range of 50-100mm and wherein the diameter (D10) of the piston rod is in the range of 5-15 mm.
14. A piston (1) for a pneumatic impact tool according to claim 1 or 2, characterized in that in the first material is defined as
Is within +/-20% of the longitudinal elastic wave velocity in the second material.
15. A piston (1) for a pneumatic impact tool according to claim 14, characterized in that in said first material is defined as
Is within +/-10% of the longitudinal elastic wave velocity in the second material.
16. A piston (1) for a pneumatic impact tool according to claim 1 or 2, characterized in that in the first material is defined as
Is less than or equal to half the longitudinal elastic wave velocity in the second material.
17. A pneumatic impact tool, characterized in that it comprises a piston according to any of the preceding claims.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922321381.4U CN212683857U (en) | 2019-12-20 | 2019-12-20 | Pneumatic impact tool and piston for a pneumatic impact tool |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922321381.4U CN212683857U (en) | 2019-12-20 | 2019-12-20 | Pneumatic impact tool and piston for a pneumatic impact tool |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212683857U true CN212683857U (en) | 2021-03-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201922321381.4U Active CN212683857U (en) | 2019-12-20 | 2019-12-20 | Pneumatic impact tool and piston for a pneumatic impact tool |
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| Country | Link |
|---|---|
| CN (1) | CN212683857U (en) |
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2019
- 2019-12-20 CN CN201922321381.4U patent/CN212683857U/en active Active
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