Description
[0001] The invention relates to the use of an assembly having a depth stop for fit- ting to a cut-off tool, which cut-off tool is fitted with a rotarily driven, exchangeable cut-off wheel (see document EP3053684 A1, which forms the basis for the preamble of claim 1).
[0002] A generic depth stop is known from both WO 2011/014914 Al and DE 36 00 809 Al.
[0003] Known from DE 10 2014 115 768 B3 is a two-piece depth stop for a drill- ing, milling or countersinking tool that incorporates internal and external component parts that can rotate relative to each other.
[0004] Known from US 5 788 561 A is a device that is used to sand down floors or produce cuts in floors. A depth stop fitted to this device incorporates a two-piece stop ring with an external exchangeable contact element.
[0005] Itis known from practice that, when connecting up pipework to already in- stalled pipework, openings have to be made in the already installed pipework. This problem arises regularly when developing new building land.
[0006] If the already installed pipework is made from a mineral material, it is often found in such cases that this already installed pipework has been repaired or rein- forced by means of a liner or a so-called inliner. For connection of the new pipework it should be noted in this case that an opening must be cut in the mineral pipework without damaging the liner. Determining the cut depth in such cases is left to the skill of the persons doing the work. If the liner is accidentally damaged, expensive and tricky repair work may be necessary.
[0007] The invention is based on the problem of specifying an assembly by means of which an opening can be made in the mineral pipework without damaging any liner fitted to such pipework.
[0008] This problem is solved by using an assembly in accordance with claim 1. Advantageous embodiments are described in the subclaims.
[0009] In other words the invention proposes using a depth stop that can be fitted to the cut-off tool together with the cut-off wheel. For this purpose the depth stop incorporates a central hole that serves to receive the axle and through which the axle of the cut-off tool can extend. This enables the depth stop to be fitted to the cut-off tool like a cut-off wheel. The depth stop further incorporates a stop ring that extends circularly all the way around the hole. This stop ring is held at its predeter- mined distance from the hole by means of a distance piece.
[0010] An assembly for producing V-cuts in a pipe body in the way proposed com- prises, on the one hand, a cut-off tool known in itself and, on the other, a cut-off wheel exchangeably held on the cut-off tool and finally the proposed depth stop, where the diameters of the depth stop and the cut-off wheel are coordinated in such a way that the diameter of the cut-off wheel is greater than the outside diame- ter of the depth stop.
[0011] The tools described in the present proposal as cut-off tools are in practice also referred to as Trennjägers (cut-off machines), angle grinders, angle cutters,
etc. These are hand-held tools, usually electrically driven.
[0012] The depth stop used in accordance with the proposal can be provided with various diameters. It can in all cases be used for the work to be carried out together with a cut-off wheel the diameter of which is larger than the diameter of the depth stop to the extent that because of the resulting projection of the cut-off wheel be- yond the depth stop a cut depth that is smaller than the wall thickness of the ce- ramic pipe body can be obtained with the cut-off tool. It has been found in practical trials that it is sufficient to produce V-cuts in the mineral pipe body in order to then achieve a complete break by means of one or more carefully applied hammer blows so that the part of the pipe wall marked off by the V-cuts can be removed from the pipe body. Because a V-cut is sufficient for this, a number of advantages result: for one thing, it can be reliably ensured that a cut depth that reliably precludes un- wanted damage to the liner is sufficient for the work to be carried out. Further, when precisely adjusting to the wall thickness of the already installed pipework be- ing worked on, it is not necessary to adjust with millimetre accuracy the diameter of the cut-off wheel and the depth stop to suit the pipe wall thickness. Accordingly a large number of different pipe types to be found in practice can be worked on with very few different cut-off wheels and depth stops so that in practice, for example, two or three different cut-off wheel diameters that can always be combined with the same depth stop without having to perhaps use two or three differently dimensioned depth stops will suffice to, on the one hand, ensure the integrity of the liner and, on the other, to be able to make a sufficiently deep notch and then ena- ble the required piece to be separated from the pipe wall by means of the afore- mentioned hammer blows.
[0013] Because the depth stop incorporates a stop ring and rotates with the cut- off wheel outstanding protection is ensured against damage to the liner. Unlike in the case of stops which are fitted on the outside of the cut-off tool and may be dis- placed, the depth stop cannot be accidentally displaced by e.g. vibration set up dur- — ing operation or sharp impacts caused by careless handling of the cut-off tool. Wear on the cut-off wheel also results in reduction of its diameter, so that the amount by which it projects beyond the depth stop is reduced accordingly and the depth of the V-cut likewise, so reliably precluding accidental damage to the liner.
[0014] The stop ring by its annular contour also ensures that, when coming up against the surface of the pipe body, it does not prevent secure handling of the cut- off tool. So, because of the annular outer contour it is ensured that, unlike with a raylike or polygonal outer contour, the depth stop cannot catch on the outside of the pipe body and so prevent further control of the cut-off tool and generation of the desired V-cut.
[0015] It can be advantageously provided for for the distance piece of the depth stop to be designed in the form of a disk. In this way, by contrast with a design having a number of separate radiating segments, an especially robust and opera- tionally reliable design of the depth stop is guaranteed. Furthermore, unwanted openings in which objects can become trapped and later detach themselves uncon- trolledly from the depth stop and pose a hazard are avoided.
[0016] This aforementioned wheel may advantageously have at its centre a drilled hole that forms the axle seating for the depth stop. In contrast to a central opening that is designed e.g. star-shaped a drilled hole provides as large a surface contact as possible between the distance piece and a centring element that extends into the drilled hole, whether it be the axle of the cut-off tool itself or a separate centring el- ement. In this way precise centring and as robust a design of the depth stop as possible are assisted.
[0017] The stop ring of the depth stop may advantageously be at least 3 mm wide. This prevents a second cut alongside the desired V-cut from being made acci- dentally in the wall of the pipework because of the depth stop. In particular the stop ring may be made considerably wider than 3 mm, for example, 5 to 10 mm wide, to reliably preclude unwanted cutting action of the stop ring.
[0018] In one embodiment the stop ring may be made from metal and have a hardened surface to ensure a long service life or useful life of the depth stop.
[0019] In another embodiment the stop ring may be provided with an easily slid- ing, low-friction surface: for example, it can be provided for for the stop ring to be made entirely of a suitably easily sliding, low-friction plastic, and, if required, the whole depth stop can be made from such plastic. Because of the low-friction design of the surface of the stop ring unwanted premature wear on the stop ring is pre- vented and also optimum care of the pipe surface ensured.
[0020] If required, the two aforementioned embodiments may be combined by, for example, providing the surface of the stop ring on a basically metal depth stop with an easily sliding, low-friction layer.
[0021] It may therefore be provided for for the stop ring to be made in two pieces, the radially inner part that is connected to the distance piece being described as a bearing element and a radially outer part of the stop ring being described as a con- tact element that will come into contact with the pipe surface when the cut-off wheel has penetrated sufficiently far into the pipe wall.
[0022] It can with such a two-piece stop ring be advantageously provided for for the bearing element to be widened radially outwards, for example, in the form of a bead running continuously all the way around or at least in the form of some areas where the cross-section of the bearing element is widened radially outwards. In this way an undercut is created, and, co-acting with this bearing element, a contact ele- ment is provided for that is held positively on the bearing element. For this the con- tact element has an essentially U-shaped cross-section that tapers radially towards the inside to enable the contact element to be held positively on the bearing ele- ment by the undercut, as required. Independently of the outside cross-sectional contour of the contact element it can be provided for for the radially inwards tapering cross-section to be realised in the form of a hollow space or a groove in the contact element.
[0023] With such a two-piece stop ring design it may be especially advantageously 5 provided for for the contact element that is held positively on the bearing element to be held on the bearing element with play. By this means relative movement be- tween the stop ring — or its outer contact element — and the axle of the cut-off tool is enabled. In this way as careful a treatment of the pipe body as possible is ena- bled: because of the aforementioned play free running is enabled between the bear- ing element and the contact element so that the rotary movement of the contact el- ement is braked — if necessary, to a standstill — by contact with the pipe body, while the bearing element can continue to rotate together with the cut-off wheel.
[0024] The cut-off tool can then continue to be guided along the groove, while contact is maintained between the contact element of the stop ring and the pipe surface so that the contact element is able to run over the pipe surface. In this way especially low-resistance guidance of the cut-off tool is achieved and the producing of the cut in the pipe wall made easier.
[0025] Because of the aforementioned positive hold of the contact element on the bearing element of the stop ring it can be advantageously provided for for the con- tact element to be arranged on the bearing element exchangeably. For example, the bearing element can be made from metal, while the contact element is designed as a plastic ring that can be clipped onto the bearing element positively.
[0026] The aforementioned two-piece design of the stop ring represents a differ- ent way of designing the depth stop so that it incorporates a radially inner first part and a radially outer second part each of which can be rotated relative to the other. For example, a ball bearing or similar bearing race that at the same time also delim- its the hole in the depth stop may be arranged at the centre of the depth stop, and the distance piece and the stop ring connect to the bearing race radially outwards. By the bearing race the distance piece and the stop are enabled to rotate inde- pendently of the drive axle of the cut-off tool — or even also to be braked to a standstill when the stop ring comes into contact with the pipe wall.
[0027] Example embodiments of the proposed depth stops are explained in greater detail in the following with the aid of purely schematic diagrams. Shown are in
Fig. 1 a plan view of a first embodiment of a depth stop,
Fig. 2 a section along the line II-II in fig. 1,
Fig. 3 a perspective view of the inside of a second example embodiment of a depth stop,
Fig. 4 a perspective view of the outside of the depth stop shown in fig. 3,
Fig. 5 a clamping screw of a cut-off tool,
Fig. 6 the head section of a cut-off tool,
Fig. 7 a view like that of fig. 6 but with a cut-off wheel added,
Fig. 8 a view like that of fig. 7 with the depth stop shown in fig. 3 and 4 loosely fitted, and
Fig. 9 a fully assembled assembly for making V-cuts.
[0028] In fig. 1 the number 1 indicates a depth stop that has a central hole 2 to receive the drive axle of a cut-off tool. Extending around and at a distance from the hole 2 is a stop ring 3 that is held at a distance from the hole 2 by means of a dis- tance piece 4. In the example embodiment shown the whole depth stop 1 is manu- factured as a one-piece metal moulding, the distance piece 4 being an annular wheel.
[0029] As is shown particularly in fig. 2, the part of the depth stop 1 around the hole 2 is designed as a clamping screw so that by means of the depth stop 1 a cut- off wheel can be mounted on a cut-off tool. For this purpose, extending around the hole 2 is a screw thread 5 that enables the depth stop 1 to be screwed onto the drive axle of a cut-off tool. Insertion holes 6 in the form of drilled holes serve to po- sition a tightening key.
[0030] The example embodiment shown in figs. 1 and 2 has a diameter of 85 mm and the outermost surface of the stop ring 3 running all the way around is 5 mm wide, enabling this surface to come into contact with a pipe body. Adjacent to this width of 5 mm are lateral chamfers or roundings so that the stop ring 3 has a total width of 8 to 9 mm.
[0031] Shown in figs. 3 and 4 is a second example embodiment of a depth stop 1 that is of a geometrically simpler design than the depth stop 1 shown in figs. 1 and 2: the example embodiment shown in figs 3 and 4 has a U-shaped cross-section overall and consists of a wheel that has in it a drilled hole for a central hole 2 and otherwise forms the distance piece 4, and with which the stop ring 3 is in contact around its outer circumference.
[0032] Fig. 5 shows a clamping screw 7, which can be used to mount the depth stop 1 shown in figs. 3 and 4. This is a commercially available clamping screw 7 of the kind also used to fasten cut-off wheels to the cut-off tool. Like the depth stop 1 shown in figs. 1 and 2, the clamping screw 7 is also provided with a screw thread 5 that enables fixture on an axle of a cut-off tool as well as insertion holes 6 for a tightening key. The clamping screw 7 incorporates a collar 8 that is adapted to fit the inner hole in cut-off wheels so that these can be centred on the axle of the cut- off tool. The hole 2 in the depth stop 1 is adapted to fit the diameter of this collar 8 in such a way that the depth stop 1 can also be centred by means of the clamping screw 7.
[0033] Shown in fig. 6 is the so-called head section of a cut-off tool 9 having a motor-driven axle 10 that is set at an angle to an electric drive motor the housing of which extends to the right out of the diagram shown in fig. 6. The axle 10 is pro- vided with an external screw thread that, for example, co-acts with the screw thread 5 of the depth stop 1 shown in figs. 1 and 2, with which, however, the clamping screw 7 also co-acts. Mounted on the axle 10 is a centring plate 11 that incorporates a centring collar 12.
[0034] Fig. 7 shows the head section of the cut-off tool 9 as shown in fig. 6 but having a cut-off wheel 14 that is fitted on the centring plate 11. A central drilled hole in the cut-off wheel 14 is dimensioned so that the cut-off wheel 14 is arranged around the centring collar 12 of the centring plate 11 with very little play.
[0035] Fig. 8 shows as the next assembly step the depth stop 1 as shown in fig. 3 fitted on the cut-off wheel 14. The central hole 2 in the depth stop 1 enables the axle 10 to extend right through the depth stop 1. Also shown in fig. 8 is that the depth stop 1 is not located centrally on the cut-off wheel 14. Instead centring is done with the aid of the clamping screw 7 still to be fitted.
[0036] Fig. 9 shows the finished assembly with which V-cuts can be produced in the pipe body. The clamping screw 7 here is aligned on the axle 10 in such a way that the collar 8 extends into the hole 2 in the depth stop 1 and in this way centres the depth stop 1 on the axle 10.
[0037] It can also be seen from Fig. 9 that the diameter of the cut-off wheel 14 is greater than the diameter of the stop ring 3. The radial projection of the cut-off wheel 14 beyond the depth stop in this way determines the maximum penetration depth of the cut-off wheel 14 into a pipe body and so the depth of a groove that can be made in a pipe wall by means of the assembly shown in fig. 9.
[0038] Reference signs: 1 depth stop 2 central hole 3 stop ring 4 distance piece 5 screw thread 6 insertion hole 7 clamping screw 8 collar 9 cut-off tool 10 axle 11 centring plate 12 centring collar 14 cut-off wheel