Abstract
An impact tool for machining workpieces has an impact mechanism which is arranged in a housing and is suitable for transmitting an oscillating movement to a machining tip arranged in an axial direction, wherein the impact mechanism can be displaced against the housing between a lower stop point and an upper stop point in the axial direction, wherein a device for generating a constant or variable contact pressure of the machining tip is arranged between the housing and the impact mechanism, such that after a prestressing path of the impact mechanism from the lower stop point, the machining tip is additionally subjected to the contact pressure.
Claims
1. An impact tool for machining workpieces having an impact mechanism (SW) which is arranged in a housing (GE) and is suitable for transmitting an oscillating movement to a machining tip (BS) arranged in an axial direction (AR), wherein the impact mechanism (SW) can be displaced against the housing (GE) between a lower stop point (AU) and an upper stop point (AO) in the axial direction (AR), wherein a means (MI) for generating a constant or variable contact pressure (AK) of the machining tip (BS) is arranged between the housing (GE) and the impact mechanism (SW), such that after a prestressing path of the impact mechanism (SW) from the lower stop point (AU), the machining tip (BS) is additionally subjected to the contact pressure (AK).
2. The impact tool according to claim 1, wherein a holding means (HM), preferably in the form of a handle, for generating a holding force (HK), is connected to the housing (GE) and is arranged on the side opposite the machining tip (BS).
3. The impact tool according to claim 2, wherein the means (MI) for generating the contact pressure (AK) is arranged on the opposite side of the housing (GE) with respect to the holding means (HM).
4. The impact tool according to claim 1, wherein the impact mechanism (SW) is designed as a pneumatic muscle or membrane, has a magnetic or piezoelectric drive, or is designed in the form of an air piston.
5. The impact tool according to claim 1, wherein the means (MI) for generating the contact pressure is provided with a mechanical, a piezoelectric, a magnetic, or a hydraulic spring element.
6. The impact tool according to claim 1, wherein the means (MI) for generating the contact pressure is designed pneumatically in the form of an air spring.
7. The impact tool according to claim 1, wherein the means (MI) for generating the contact pressure can be regulated via a regulating circuit (RE).
8. The impact tool according to claim 7, wherein an inclination sensor (NS) is provided which transmits a spatial orientation of the impact tool (SL) to the control circuit (RE), such that a constant force application of the machining tip (BS) can be generated independently of the spatial orientation of the impact tool (SL).
9. The impact tool according to claim 1, wherein one or more optical or acoustic displays (AZ) of the prestressing path are provided within the lower stop point (AU) and the upper stop point (AO).
10. The impact tool according to claim 1, comprising an automatic start circuit which activates the impact mechanism (SW) when a minimally specified prestressing path is reached.
11. The impact tool according to claim 10, wherein a hand switch is provided which overwrites the automatic start circuit with respect to the switching off of the impact mechanism (SW).
12. The impact tool according to claim 1, wherein the impact mechanism (SW) is provided with at least one supply line (ZL) which generates the oscillating movement via a suitable control.
13. The impact tool according to claim 12, wherein the supply line (ZL) can be displaced together with the impact mechanism (SW) relative to the housing (GE).
14. The impact tool according to claim 12, wherein the supply line (ZL) is fixed relative to the housing (GE).
15. The impact tool according to claim 14, wherein the supply line (ZL) is connected to an opening (OE) on the housing (GE) which opens into a receptacle (AU) on the impact tool (SW), said receptacle being arranged in the axial direction and being dimensioned in such a way that an uninterrupted connection with the supply line (ZL) can be achieved between the lower stop point (AU) and the upper stop point (AO).
Description
[0026] Some embodiments are explained in more detail below with reference to the drawings. In the drawings:
[0027] FIG. 1 is a perspective side view of an impact tool of the invention according to a first embodiment,
[0028] FIG. 2 is a sectional view of the impact tool from FIG. 1,
[0029] FIG. 3 is the impact tool from FIG. 1 in a first position of the impact mechanism in a sectional view,
[0030] FIG. 4 is the impact tool from FIG. 1 in a second position of the impact mechanism in a sectional view,
[0031] FIG. 5 is the impact tool from FIG. 1 in a third position of the impact mechanism in a sectional view,
[0032] FIG. 6 is a sectional view of an impact tool according to the invention according to a second embodiment,
[0033] FIG. 7 is a sectional view of an impact tool of the invention according to a third embodiment,
[0034] FIG. 8 is a first schematic representation of the use of an impact tool according to the invention,
[0035] FIG. 9 is a second schematic illustration of the use of an impact tool according to the invention,
[0036] FIG. 10 is a sectional view of an impact tool of the invention according to a fourth embodiment in a first position of the impact mechanism, and
[0037] FIG. 11 is a sectional view of the impact tool according to FIG. 10 in a second position of the impact mechanism.
[0038] In the figures, the same or functionally equivalent components are provided with the same reference numerals.
[0039] FIG. 1 shows a three-dimensional representation of an impact tool SL in a perspective side view. The impact tool SL has a housing GE, in the interior of which there is an impact mechanism SW. On the side of the impact tool SL facing a workpiece WS there is a machining tip BS which can be designed, for example, in the form of a chisel having a rounded end. The machining tip BS is periodically set in motion in an axial direction AR by an oscillating, preferably periodic, movement of the impact mechanism SW. The periodic movement of the machining tip BS can typically be between 70 Hz and 120 Hz, so that the machining can be carried out in the form of higher-frequency hammering of welds on the workpiece WS. However, the apparatus according to the invention can also be used in other work which requires a pendulous, preferably periodic movement.
[0040] In addition to a handle GR arranged on the side, the housing GE has a holding means HM on the side opposite the machining tip BS, which can be designed, for example, in the form of a holding bracket or handle. In the case of robot machining, instead of or in addition to the handle GR, a corresponding receptacle mount would be provided as the holding means HM. A holding force can be exerted by a user in the direction of the machining tip BS along the axial direction AR by means of the holding means HM. In known apparatuses from the prior art, this holding force is transmitted as a contract pressure to the machining tip BS for higher-frequency hammering. According to the invention, however, the impact mechanism SW can be displaced against the housing GE, which can be recognized by the elongated design of the housing opening GO.
[0041] The impact mechanism SW can be designed as a pneumatic muscle or as a pneumatic membrane. In other embodiments, however, it would also be possible to use a magnetic or a piezoelectric drive or to design the impact mechanism SW in the form of an air piston. The specific design of the impact mechanism SW is not relevant to the invention, although a pneumatic muscle or a pneumatic membrane is preferred.
[0042] In order to better illustrate the displaceability of the impact mechanism SW against the housing GE, reference is made below to FIG. 2, which shows a sectional view of the impact tool SL according to FIG. 1. The section plane is chosen along the axial direction AR in the plane spanned by the holding means HM.
[0043] It can be seen in FIG. 2 that the impact mechanism SW can be displaced between a lower stop point AU and an upper stop point AO, wherein the maximum stroke is identified as the travel VW. The impact mechanism SW, together with the machining tip BS, is only shown schematically as a unit. To move the impact mechanism SW inside the housing GE, several guides FR are provided, which can be arranged, for example, in the area above the lower stop point AU and in the area in the direction of the machining tip BS. Furthermore, a means MI for generating a contact pressure AK is arranged on the side of the housing GE opposite the holding means HM between the impact mechanism SW and the housing GE. The means MI for generating the contact pressure AK can be provided, for example, as a mechanical spring element, so that the impact mechanism SW bears against the lower stop point AU of the housing GE before the machining begins. In order to generate a certain contact pressure AK, a holding force HK is first exerted using the holding means HM, as will be explained below with reference to FIGS. 3 to 5, such that, as shown in FIG. 3, the impact mechanism SW is moved away from the lower stop point AU by one prestressing path VS. As soon as this prestressing path VS has a minimum value, the minimal contact pressure AK is reached by means of the spring of the means MI for generating the contact pressure AK.
[0044] The contact pressure AK of the impact mechanism SW thus corresponds to the spring force of the means MI. In order to be able to change the contact pressure AK, the spring element of the means MI could, for example, be prestressed differently by means of a corresponding turntable (not shown in FIG. 3) which would make it possible, for example, to adjust the contact pressure AK manually. In other embodiments, the impact mechanism SW can also be activated automatically, wherein by reaching the minimal prestressing path VS via a starting circuit ST, which is indicated schematically in FIG. 3 as a switch, the impact mechanism SW is automatically activated.
[0045] In FIG. 4, the impact mechanism SW is at a further distance from the lower stop point AU due to increasing holding force HK or changing distance between the machining tip BS and workpiece WS. However, this first travel VW is still in an area in which the impact mechanism SW can work without hitting the upper stop element. According to FIG. 4, the larger first prestressing path VS' is also connected to a larger contact pressure AK, since the spring element of the means MI typically generates displacement-dependent spring forces.
[0046] FIG. 5 shows the situation in which the impact mechanism SW is deflected even further from the lower stop point AU almost to the upper stop point AO. As already mentioned in connection with FIG. 4, this can be caused both by an increasing holding force HK on the holding means HM or by a decreasing distance between the machining tip BS and workpiece WS. As soon as the deflection, which is identified in FIG. 5 by means of the second prestressing path VS, reaches a value which no longer allows the impact mechanism SW to work safely, this could activate a switch SC, for example, so that an optical display, indicated schematically in FIG. 5 on the side of the housing GE, is activated. The display AZ could, for example, be a light-emitting diode that indicates the deflection up to the second prestressing path VS by means of a signal color. The second prestressing path V corresponds to a second travel VW.
[0047] In other embodiments, reaching the determined minimal prestressing path VS, as shown in FIG. 3, could also be signaled by means of the display AZ or a further display AZ (not shown). Instead of an optical display using a light-emitting diode, an acoustic display would also be conceivable. Likewise, an electrical signal could also be emitted instead of a display AZ, which would be particularly advantageous when using the impact tool SL in a robot or a robot arm. The optimal working area corresponds to the area of the complete travel VW reduced by the travel distance VW and the prestressing travel VS.
[0048] When machining, for example, along or around an edge on the workpiece WS, a brief placement of the machining tip BS could result in the prestressing path VS falling below the minimum. In the embodiment according to FIG. 3, the start circuit ST would therefore ensure that the impact mechanism SW was switched off. However, since frequent switching on and off of the impact mechanism SW would be disruptive in such applications, a hand switch HS can be provided which allows a user to overwrite the switching off of the start circuit ST. Instead of a hand switch HS, an electrical signal can also be provided here, which is generated, for example, by a control system of a robot or a robot arm or is stored in the path program of the machining path.
[0049] The embodiment of the invention previously shown in connection with FIGS. 1 to 5 uses a simple spring as means MI for generating the contact pressure AK, wherein said spring can be mechanically or automatically adjusted, for example. Some further embodiments are shown below, which differ with regard to the configuration of the means MI for generating the contact pressure AK.
[0050] FIG. 6 shows the impact tool SL in a further embodiment, wherein the contact pressure AK between the housing GE and the impact mechanism SW is adjustable here. The means MI is equipped with a pneumatic spring element in the form of air bellows, wherein the air bellows of the means MI is connected to a pressure valve DV via a fluid channel FK and a fluid line FL. The pressure valve DV is adjustable and is fed on the input side via a further fluid line FL from a pneumatic pump FP. It is thus possible, via the adjustability of the pressure valve DV, which can be done both manually and automatically, to design the contact pressure AK of the means MI accordingly. In addition to the example shown with a pneumatic spring element, adjustability is also possible with mechanical, hydraulic, or electrical means MI. The air bellows LB can accordingly be replaced by other spring elements.
[0051] A further embodiment of the invention is explained below with reference to FIG. 7. In contrast to the air bellows LB, the embodiment according to FIG. 7 has an air piston LK, which is also connected to an adjustable pressure control valve DV via a fluid channel FK and a fluid line FL. The pressure control valve DV is in turn connected to a pneumatic pump FP via the further fluid line FL. The adjustability of the pressure control valve DV is carried out according to the embodiment according to FIG. 7 via an inclination sensor NS, which in its simplest form is only designed as an inclination switch in order to be able to recognize overhead work. In yet other configurations, the inclination sensor NS can output the spatial arrangement of the impact tool SL. Since, depending on the spatial arrangement, the weight of the impact tool SL is added to or subtracted from the holding force HK, compensation of the contact pressure AK can be achieved by means of the inclination sensor independently of the spatial arrangement of the impact tool SL. A suitable control circuit is provided for this purpose, which can be implemented, for example, as a PLC control. The control circuit RE is only schematically shown in FIG. 7.
[0052] The controllability of the means MI for generating the contact pressure AK can be expanded with additional data. For example, in the case of automated machining using a robot or a robot arm, a current coordinate value of the machining path could be generated, which is then passed on to the control circuit RE.
[0053] In this way, a force compensation with regard to the contact pressure or a path compensation with regard to varying distances between the machining tip BS and the workpiece WS can also be generated for a given machining path.
[0054] This is explained again with reference to FIGS. 8 and 9.
[0055] The intended machining path BA, for example of a robot or a robot arm, is illustrated in the schematic illustration according to FIG. 8. With a contour of the workpiece WS that is not resolved, for example, by the machining path BA, the distance between the machining tip BS and the workpiece WS would change, which would result in different prestressing paths. Accordingly, the contact pressure AK or the available stroke with respect to the prestressing path also changes. The control circuit RE can compensate for the different distances X and Y shown in FIG. 8, wherein said compensation is caused by the contour of the workpiece WS.
[0056] A workpiece WS is shown in FIG. 9, in which the machining path is carried out overhead in a first position, as is illustrated by the contact pressure AK. In a second position, which is characterized by the contact pressure AK, machining takes place in the horizontal direction. The third machining position according to the contact pressure A takes place in the direction of the floor. Consequently, the weight of the impact mechanism with respect to the contact pressure AK and the contact pressure AK has different effects, since the weight force with respect to the impact mechanism SW acts once in the direction of the contact pressure and once counter to it. With regard to the contact pressure AK, an increased friction in the impact mechanism SW would be noticeable, since an increased friction or at least a changed friction with respect to the guides FR must be expected here. Through the regulation by means of the regulation, the pressure valve DV can now be changed on the basis of the inclination sensor NS in such a way that the contact pressure remains the same or approximately the same for all three positions AK, AK, and AK. This corresponds to a force compensation with regard to the regulation of the contact pressure AK.
[0057] FIG. 10 shows a further embodiment of the impact tool SL. The representation in FIG. 10 takes place in a sectional view similar to the representation in FIG. 2. In contrast to the previous exemplary embodiments, a supply line ZL for fluid supply, for example for a pneumatic muscle, is connected directly to the housing GE. In order to be able to displace the impact mechanism SW between the lower stop point and the upper stop point, the supply line extends via the channel-shaped opening OE to a receptacle AF formed in the axial direction AR. The receptacle AF is dimensioned such that the channel-shaped opening OE can receive fluid via the supply line ZL both when the impact mechanism is positioned near the lower stop point AU and when the impact mechanism is positioned in the region of the upper stop point AO. Accordingly, an uninterrupted connection to the supply line ZL is possible. The receptacle AF is preferably designed in an annular shape in order to allow a simple seal to the area above or below when the impact mechanism SW moves.
[0058] It can also be seen from FIG. 10 that the fluid line FL can be passed on to the corresponding pneumatically controllable means MI via the fluid channel FK, which can also be carried out, for example, by a cover DE, which forms part of the housing GE. The distribution of the fluid via the fluid channels FK in the interior of the cover DE makes it possible to provide a plurality of means MI without having to provide additional lines in the interior of the housing GE. The part of the fluid channel FK assigned to the fluid line FL must in turn be arranged in such a way that the impact mechanism SW can be displaced over the entire area between the lower stop point AU and the upper stop point AO. A displacement of the impact mechanism SW in the direction of the upper stop point AO is shown in FIG. 11. It can be seen that both the supply line ZL and the fluid line FL can provide a corresponding supply.
[0059] The embodiment of the impact tool SL shown in FIGS. 10 and 11 allows for a particularly compact structure, which is also low-maintenance, since, for example, by removing the cover DE on the housing GE or by removing parts of the two-part housing GE, for example, access to the pneumatically adjustable means MI and the impact mechanism SW is possible. In particular, the complete impact mechanism SW can be replaced, which leads to a significant improvement in ease of maintenance.
[0060] The features indicated above and in the claims, as well as the features which may be seen in the figures, may be advantageously implemented both individually as well as in various combinations. The invention is not limited to the exemplary embodiments described, but may be modified in many ways within the scope of expert knowledge.
LIST OF REFERENCE NUMERALS
[0061] AF receptacle [0062] AK contact pressure [0063] AK contact pressure [0064] AK contact pressure [0065] AO upper stop point [0066] AR axial direction [0067] AU lower stop point [0068] AZ display [0069] BA machining path [0070] BS machining tip [0071] DE cover [0072] DV pressure control valve [0073] DV pressure valve [0074] FK fluid channel [0075] FL fluid line [0076] FL fluid line [0077] FP pneumatic pump [0078] FR guides [0079] GE housing [0080] GO housing opening [0081] GR handle [0082] HK holding force [0083] HM holding means [0084] HS hand switch [0085] LB air bellows [0086] LK air piston [0087] MI means [0088] NS inclination sensor [0089] OE opening [0090] RE control circuit [0091] SC switch [0092] SL impact tool [0093] ST start circuit [0094] SW impact mechanism [0095] VS prestressing path [0096] VS' prestressing path [0097] VS prestressing path [0098] VW travel [0099] VW travel [0100] WS workpiece [0101] ZL supply line
