PRESSURE-CONTROLLED COUNTERSINKING TOOL WITH BLADE CENTERING

Description

[0001] The subject of the invention is a pressure-medium controlled countersinking tool according to the preamble of patent claims 1 and 2.

[0002] Such a countersinking tool is known, for example, from US 3 572 182 A.

[0003] Furthermore, the invention relates to a countersinking tool with one or two pivoting knives, wherein each knife can be actuated by its own piston-cylinder unit or both knives can be actuated together by a single piston-cylinder unit.

[0004] When arranging two knives, it is further preferred if one knife can be pivoted out at the front of a knife window arranged in the knife housing, while the other knife can be pivoted out of the rear of the knife window with a complementary movement sequence.

[0005] For the sake of simplicity, however, the following description assumes that only one blade is present, to which a piston-cylinder unit actuated by a pressure medium is assigned, although the invention is not limited to the arrangement of a single blade. Regarding the operation of such a pressure-medium-controlled countersinking tool, reference is generally made to the subject matter of DE 10 2009 012 996 A1.

[0006] EP 2 589 451 B1, which goes back to the same applicant, describes another pressure-medium-controlled countersinking tool with a piston-cylinder unit, wherein with regard to the structure and the mode of operation, reference is made to the disclosure content of EP 2 589 451 B1.

[0007] However, the present invention is not limited to a countersink blade that can be pivoted out under centrifugal force. The invention therefore also provides pressure-controlled countersink tools in which either the outward pivoting or the return pivoting, or both pivoting processes, are carried out with any desired drive force. These pressure-controlled countersink tools, which originate from the same applicant, can be optimized with regard to countersinking accuracy and the reproducibility of the countersink produced in a workpiece bore.

[0008] When operating countersinking tools according to the subject matter of DE 10 2009 012 996 A1 or EP 2 589 451 B1, it has been found that a necessary amount of play must be present in the bearing bore for the pivot bearing of at least one knife in order to be able to smoothly pivot the (at least one) knife out of the knife window without risking the knife bearing breaking. This resulted in maximum countersinking accuracy and a countersinking reproducibility of + / - 0.2 mm.

[0009] The invention is therefore based on the object of developing a pressure-medium-controlled countersinking tool of the type mentioned above in such a way that the countersinking accuracy and the countersinking reproducibility are significantly improved.

[0010] To achieve the stated object, the invention is characterized by the technical teaching of claims 1 and 2.

[0011] The technical teaching of the invention, for the first time, achieves the advantage of achieving a countersinking accuracy of at least + / - 0.1 mm. This represents a significant advance, as such countersinking accuracies were previously unattainable with pressure-controlled countersinking tools. By installing a purely radial knife centering mechanism in the knife housing, the knife is centered positively and without play during the machining process. At the same time, the necessary axial play in the knife bearing can be maintained.

[0012] This centering enables very high reproducibility of the countersink with minimal variation. Due to the appropriate manufacturing precision, this centering also enables absolute countersinking accuracy, which meets the more stringent market requirements.

[0013] The cutting process creates an axial cutting force on the knife, which – in a first preferred embodiment – ​​presses the knife with its centering groove against a centering bolt on the housing side of the knife housing, centering and securing it in its centering axis with a positive fit. The rounded, profiled contact surfaces of the transverse centering groove arranged in the knife engage positively with complementary, also rounded contact surfaces of a centering bolt on the housing side, centering the knife on the housing side centering bolt along its centering axis, which runs in the longitudinal direction of the knife.

[0014] Thus, the centering device according to the invention secures the knife against radial displacement along the centering axis.

[0015] In other words, this means that the centering device according to the invention secures the knife against any displacement play of the bearing pin in the bearing bore on the base body side.

[0016] The centering device is preferably designed such that, in the swiveled-out working state of the knife, it carries out a positive centering of the knife in the centering axis, whereby such centering is not necessary in the swiveled-in state.

[0017] The centering device is preferably arranged at a distance from the bearing pin in the bearing bore, which is subject to play.

[0018] In addition to the first preferred embodiment described above, there are several further embodiments for the design of the centering device, wherein all embodiments have in common that there is a positive engagement of projections or recesses arranged on the knife in associated recesses or projections on the knife housing side, at least in the pivoted-out state of the at least one knife.

[0019] In the first preferred embodiment of the invention, it is provided that the centering device consists of a centering groove arranged on the base side of the underside of the knife, which in the machining position is in positive engagement with a centering bolt on the housing side and that the centering bolt is roundly profiled and protrudes with its upper part of its outer circumference from a housing-side receiving bore and there forms a complementary centering surface for engagement in the centering groove.

[0020] The base-side centering groove can therefore be designed as a transverse groove in the base area of ​​the knife and interacts with a positive engagement with part of a housing-side centering bolt.

[0021] The invention is not limited to this. In another embodiment of the invention, the kinematic reversal of the first embodiment can be provided, in which the centering pin is arranged on the base side of the blade and can be brought into engagement with a transverse centering groove on the housing side.

[0022] In this design, it is particularly advantageous if the centering bolt has a round profile and the upper part of its outer circumference protrudes from its receiving bore (on the blade) and forms a complementary centering surface for engagement in the centering groove (on the housing).

[0023] For the sake of simplicity, the following description assumes the first kinematic embodiment, in which the centering pin is arranged on the housing side and fits into a housing-side receiving bore, and the complementary centering groove is designed as a transverse centering groove on the base side of the blade. This simplified description is provided solely for the sake of simplicity, without limiting the invention to this one kinematic embodiment.

[0024] In any case, attaching a centering bolt to the housing side is easier to manufacture than attaching such a centering bolt to the base side of a knife.

[0025] When attaching the centering pin to the housing, it is preferable for it to be replaceable. This allows it to be pulled out of its transverse bore in the direction of its longitudinal extension. This allows the centering pin to have different material properties than the blade material and can also be replaced when it shows signs of wear.

[0026] The centering pin can also be designed as a spring-loaded element that snaps into the centering groove, formed as a transverse groove, on the base side of the blade when swung out. This can be a locking over-center connection.

[0027] In a further embodiment of the invention, it is provided that the centering device consists of a centering feature arranged either on the top side or on the base side of the knife, which can be brought into positive engagement with a complementary centering groove on the housing side in the machining position.

[0028] During operation, it was found that the axial cutting force generated by the machining process presses the knife with its centering groove or its centering feature against the centering bolt or against the centering groove in the knife housing, centering and securing the knife in the centering axis in a form-fitting manner in the knife housing. It was determined that the main cutting forces are transferred to the knife housing via contact points in the knife window and not via the pivot bearing, consisting of the bearing bolt and locating bore. This was the reason why sufficient play had to be provided in the knife bearing in state-of-the-art countersinking tools. However, the invention now provides for the only remaining degree of freedom, which acts radially and influences the countersinking result, to be eliminated with the new centering device.

[0029] Chip removal, which played a major role in the subject matter of DE 10 2009 012 996 A1, plays only a minor role in the current system because sufficient flushing is provided with the cooling lubricants present in the machining process. This ensures that the centering devices according to the invention are kept free of chips. The positive and thus sealing engagement of the knife-side centering parts with the associated, complementary centering parts on the housing also plays a role, because this positive engagement protects the centering device from the ingress of chips.

[0030] The centering device essentially seals itself during the machining process, as a positive engagement prevents chips from entering the centering device. Should chips accumulate in the centering device, they are removed when the knife is pivoted into the centering device.

[0031] If one of the subclaims merely describes the deburring of a bore in reverse countersinking mode, this is not to be understood as limiting. The invention relates to all operating modes of a countersinking tool, regardless of whether deburring occurs in forward or reverse countersinking mode.

[0032] In a further preferred embodiment, it can be provided that additional, further centering devices for centering the knife in the centering axis are arranged on the side surfaces of the knife window.

[0033] It is thus provided that not only the roof-side or base-side centering devices according to the invention are provided between the at least one blade and the associated surfaces in the blade housing, but also further centering devices arranged perpendicular thereto, which are arranged in the side surfaces of the blade window.

[0034] The invention is explained in more detail below with reference to drawings illustrating only one embodiment. Further essential features and advantages of the invention will become apparent from the drawings and their description.

[0035] They show: Figure 1: Section through a pressure medium controlled countersinking tool with radial centering of the knife Figure 2: Perspective view of the knife Figure 3: A preferred embodiment of a knife in perspective view Figure 4: The side view of the knife according to Figure 3with further details Figure 5: the countersinking tool according to Figure 1 with retracted knife Figure 6: the countersinking tool after Figure 1 with an extended knife, which is in the lowering position Figure 7a: the same representation as Figure 6 with the specification of a drawing detail Z Figure 7b: the drawing detail Z from Figure 7a Figure 8: one opposite Figure 6 modified first embodiment Figure 9: a Figure 6 modified second embodiment

[0036] In Figure 1 the preferred embodiment of a countersinking tool 1 is shown, which essentially consists of a cylindrical base body 2 which is driven to rotate about its longitudinal axis in the direction of arrow 20 and in the opposite direction thereto, wherein a feed bore 14 is arranged in the upper region of the base body 2, through which a pressure medium 13 is pressed in the direction of arrow 15 into a cylinder chamber 25 of the base body 2.

[0037] A piston 24 is mounted in the cylinder chamber 25 for displacement in the longitudinal direction of the base body. Upon displacement, the piston drives a head piece 29 via a suitable piston rod to which a pressure element is attached. The head piece 29 is part of a control pin 27 that is displaceably driven in a longitudinal bore 12 of the base body. The pin end 30 of the head piece acts on the free, pivotable end of a blade 7 pivotably mounted on a bearing pin 9. The control pin 27 is actuated in the direction of arrow 28 against the force of a compression spring 31, the lower end of which bears against a stop 32 on the housing side. This ensures the spring-loaded return of the control pin 27 when the pressure medium 13 is no longer applied to the piston 24. Other return drives can also be used instead of a spring return.

[0038] To limit the stroke of the piston 24, a stop screw 33 is screwed into the base body 2, the end of which projects into the displacement path of the piston 24.

[0039] Furthermore, a cylindrical chamber 26 is arranged in the base body 2, through which the pressure medium 13 flows in the manner of a flushing agent stream, which is directed downward into the knife chamber 5 via a bypass bore 17 running in the extended part of the knife housing 3. This ensures that the knife chamber 5 is sufficiently flushed with the pressure medium 13 and that the entire knife chamber 5 is kept free of chips.

[0040] The knife housing 3 is preferably arranged detachably on the base housing 2 and at least one fastening screw 4 is used to connect the two parts.

[0041] The Figure 1shows the knife 7 pivoted out of the knife window 6 in its cutting position, whereby the entire countersinking tool 1 is driven in rotation in the direction of rotation 20.

[0042] The knife 7 is mounted with a bearing pin 9 in an associated bearing bore 16 (see Figure 2 ) pivotally mounted, whereby the two parts 9, 16 form a horizontal pivot axis 9a.

[0043] During the machining process, the lateral cutting edge 8 on the knife 7 engages with a bore edge (not shown in detail), the edge of which is deburred and / or countersunk.

[0044] In the prior art, the knife 7 pivoted out in the lowered position still had an undesirable degree of freedom in the bearing bore 16, which is now eliminated by the centering devices according to the invention.

[0045] The unwanted degree of freedom is in Figure 7bshown as a radial displacement 47 in the arrow directions 39, 40 along the centering axis 48. According to the invention, the centering device in the preferred first embodiment consists of a centering groove 21 introduced on the base side of the underside of the knife 7, which is designed as a transverse groove and whose longitudinal extent is parallel to the longitudinal extent of the bearing pin and the bearing bore 16.

[0046] In order to eliminate the movement play in the directions of the arrows 39, 40 and to ensure centering along the centering axis 48, it is provided that in the machining position shown, a receiving bore 22, which is at least half-open, is provided at the bottom of the knife window 6 (see Figure 7b) receives a preferred round-profile centering bolt 23, which protrudes only with its upper outer circumference from the receiving bore 22 in order to ensure centering on the complementary contact surfaces 35, 36 of the centering groove 21 with its circumferential centering surfaces.

[0047] Out of Figure 2 It also follows that the bolt end 30 of the control bolt 27 acts on spaced-apart control surfaces 18, 19 in order to move the knife from the extended cutting position in the direction of arrow 10 into its pivoted-in position.

[0048] From the Figure 7a in connection with the Figure 7b further details can be seen.

[0049] The machining process creates an axial machining force 34 which presses the knife 7 with the centering groove 21 against the centering bolt 23 in the knife housing 3 and centers and fixes it in a form-fitting manner both in the direction of arrow 39 and in the direction of arrow 40, whereby a radial displacement 47 acting in these directions 39, 40 is eliminated and a centering axis 48 is defined which prevents a displacement of the knife 7 in the directions of arrows 39, 40 in the knife housing 3.

[0050] The Figures 3 and 4 the knife 7 with its lateral cutting edge 8, where it can be seen that the preferred centering groove 21 is arranged as a transverse groove on the base side of the knife at a distance 44 from the bearing bore 16. The centering groove 21 has a centering angle 41 that is complementary to the outer circumference of the centering bolt 23, which is mounted in a receiving bore 22 in the knife housing 3, essentially free of play but preferably replaceable.

[0051] Only the upper outer circumference of the centering bolt 23 protrudes from the receiving bore 22 in order to provide complementary contact surfaces to the outer circumference of the centering bolt 23 at the contact points 37, 38 on the knife side.

[0052] The Figure 5 shows in comparison to Figure 6 that when the knife is swung in, Figure 5 the centering device is disengaged, ie the entire pivotable part of the knife 7 is accommodated in the knife chamber 5.

[0053] Only when the knife 7 after Figure 6 in the direction of arrow 11 into its extended and radially centered cutting position, there is a positive engagement of the contact points 37, 38 of the knife 7 on the upper outer circumference of the centering bolt 23 according to Figure 7b .

[0054] In Figure 7bthe conditions just described are shown graphically, whereby a centering axis 48 is also symbolically indicated, which eliminates the radial displacement 47 symbolized by the arrows 39, 40 and holds the knife centrally and positively on the upper outer circumference of the centering bolt 23.

[0055] The centering bolt 23 can be fitted without play into an associated fit in the mounting hole 22. This means that it has no play in the mounting hole 22 and sits firmly there.

[0056] In another embodiment, not shown in the drawing, the centering pin 23 can also be replaceably accommodated in the receiving bore 22. It can then be knocked out of the receiving bore 22 using a suitable tool for replacement.

[0057] The material of the centering pin 23 is independent of the material of the blade housing 3, meaning that the centering pin 23 can also be made of a hardened metal material. It can also be made of a softer metal than the material of the blade. It can also be made of a plastic material.

[0058] In another embodiment, not shown in detail in the drawing, it can also be provided that the centering bolt 23 is designed as a spring bolt, so that its outer circumference is spring-loaded and radially outwardly biased. When the centering groove 21 arranged on the base side of the blade 7 is placed on the centering bolt 23 designed as a spring bolt, a positive snap connection is formed between the groove on the blade side and the spring bolt on the housing side. When the blade is pivoted in the direction of arrow 10 into its pivoted-in position according to Figure 5this snap connection is released again.

[0059] The Figures 8 and 9 show two further embodiments of a centering device, where Figure 8 It can be seen that the centering device, at a distance 45 from the pivot axis 9a of the bearing pin 9, consists of a protrusion 43 formed on the base side of the blade 7, which does not necessarily have to extend across the entire width of the blade. It can also be present in a point-like manner or consist of several centering protrusions 43 arranged at a distance from one another. The one or more centering protrusions 43 protruding from the base side of the blade 7 then engage in a form-fitting manner in associated, complementary centering grooves 42 or centering protrusions that are arranged countersunk in the base surface of the blade window 6. There are also various possibilities for this.

[0060] One or more half-open centering grooves can be arranged next to each other on the foot side of the knife window 6 and aligned in the same transverse line.

[0061] In another embodiment, it can be provided that the centering groove 42 formed in a recess in the base side of the knife window extends over the entire width of the knife window.

[0062] The same representation also applies to a kinematic modification of the Figure 9 There it can be seen - using the same information given above - that the centering arrangement 42, 43 is not arranged on the foot side of the knife 7, but on the opposite side, namely at a distance 46 from the pivot axis 9a of the bearing pin 9. The same information applies to the design of the parts of the centering device shown there as it does with regard to the centering device 42, 43 in Figure 8were given.

[0063] Overall, with the arrangement of the centering devices 21, 23; 42, 43 described here, a precisely defined centering axis 48 was created and a radial displacement 47 in the arrow directions 39, 40 was effectively eliminated.

[0064] It is important that the centering device protects the knife from displacement along the centering axis 48 and not from tilting. Tilting does not need to be compensated or corrected by the centering device because the knife rests against the left and right surfaces of the knife window in this direction, thus sufficiently restricting its degree of freedom.

[0065] This has improved the countersinking accuracy by a factor of 10 compared to conventional state-of-the-art countersinking tools. Drawing legend

[0066] 1 Countersinking tool 2 Base body 3 Blade housing 4 Fastening screw 5 Blade chamber 6 Blade window 7 Blade 8 Cutting edge 9 Bearing bolt 9a Swivel axis 10 Direction of arrow 11 Direction of arrow 12 Longitudinal bore 13 Pressure medium 14 Feed bore 15 Direction of arrow 16 Bearing bore (of 7) 17 Bypass bore 18 Control surface 19 Control surface 20 Direction of rotation 21 Centering groove (of 7) 22 Mounting bore (of 3) 23 Centering bolt 24 Piston 25 Cylinder chamber 26 Cylinder chamber 27 Control bolt 28 Direction of arrow (of 27) 29 Head piece (of 27) 30 Bolt end (of 27) 31 Compression spring 32 Stop 33 Stop screw 34 Axial cutting force 35 Contact surface 1 (of 21) 36 Contact surface 2 (of 21) 37 Contact point 1 38 Contact point 2 39 Arrow direction 40 Arrow direction 41 Centering angle 42 Centering groove (of 3) 43 Centering feature (of 7) 44 Distance (between 9a and 21) 45 Distance (between 9a and 42, 43) 46 Distance (between 9a and 42, 43) 47 Radial displacement 48 Centering axis

Claims

1. Pressure medium-controlled countersinking tool (1) having one or more machining blades (7) arranged in a rotatably driven base body (2) which can be actuated in their pivot position by supplying a pressure medium (13), wherein actuation of the at least one blade (7) takes place via at least one piston-cylinder unit (24, 25) actuated by the pressure medium (13), wherein the at least one blade (7) is pivotably mounted on a bearing bolt (9) forming a pivot axis (9a) and can be pivoted out from a blade window (6) arranged in the blade housing (3), wherein a centring device (21, 23, 42, 43) is arranged between the blade (7) and the blade window (6) of the blade housing (3) at a radial distance (44, 45, 46) from the pivot axis (9a) and in the pivot range of the at least one blade (7), characterised in that the centring device (21, 23) consists of a centring groove (21) arranged on the base side on the underside of the blade (7) and which is in positive engagement with a housing-side centring bolt (23) in the machining position and in that the centring bolt (23) is profiled to be round and projects with its upper part of its outer circumference from a housing-side receiving bore (22) and forms a complementary centring surface there for engagement in the centring groove (21).

2. Pressure medium-controlled countersinking tool (1) having one or more machining blades (7) arranged in a rotatably driven base body (2) which can be actuated in their pivot position by supplying a pressure medium (13), wherein actuation of the at least one blade (7) takes place via at least one piston-cylinder unit (24, 25) actuated by the pressure medium (13), wherein the at least one blade (7) is pivotably mounted on a bearing bolt (9) forming a pivot axis (9a) and can be pivoted out from a blade window (6) arranged in the blade housing (3), wherein a centring device (21, 23, 42, 43) is arranged between the blade (7) and the blade window (6) of the blade housing (3) at a radial distance (44, 45, 46) from the pivot axis (9a) and in the pivot range of the at least one blade (7), characterised in that a centring bolt, which can be engaged in a housing-side transversely running centring groove (42), is arranged on the base side of the blade (7).

3. Pressure medium-controlled countersinking tool (1) according to claim 1, characterised in that the centring groove (21) is arranged as a transverse groove on the base side of the blade (7) at the distance (44) from the bearing bore (16).

4. Pressure medium-controlled countersinking tool (1) according to claim 1 or 2, characterised in that the centring groove (21) is configured as a transverse groove and the longitudinal extension thereof is parallel to the longitudinal extension of the bearing bolt (9) and the bearing bore (16).

5. Pressure medium-controlled countersinking tool (1) according to one of claims 1, 3 or 4, characterised in that the receiving bore (22) is configured as an at least half-open receiving bore (22) which is introduced on the floor of the blade window (6).

6. Pressure medium-controlled countersinking tool (1) according to one of claims 1 or 3 to 5, characterised in that the housing-side centring bolt (23) is received replaceably in the housing-side receiving bore (22).

7. Pressure medium-controlled countersinking tool (1) according to claim 2, characterised in that the centring bolt is profiled to be round and is fitted in a blade-side receiving bore and with the upper part of its outer circumference projects from the receiving bore and forms the centring surface there for engagement in the centring groove (42) of the blade housing (3).

8. Pressure medium-controlled countersinking tool (1) according to one of claims 2 or 7, characterised in that the one centring groove (42) moulded to be recessed in the base side of the blade window (6) extends over the entire width of the blade window (6).

9. Pressure medium-controlled countersinking tool (1) according to one of claims 1 to 8, characterised in that during blade centring, the two blade-side contact surfaces (35, 36) of the centring groove (21, 43) rest on the complementary cylinder surface of the housing-side centring bolt (23, 43) and thus centre the blade (7) in the centring axis (48) positively and free of play in the blade housing (3).

10. Pressure medium-controlled countersinking tool (1) according to one of claims 1 to 9, characterised in that the blade (7) in the moved-in state moves through a bore in a workpiece to be countersunk on the rear side and in the state moved out from the blade window (6) generates rearward countersinking on the rear-side bore of a workpiece.

11. Pressure medium-controlled countersinking tool (1) according to one of claims 1 to 10, characterised in that the blade (7) is centred in axial direction along the central axis of the bearing bolt (9) or the bearing bore (16) in the blade window (6).

12. Pressure medium-controlled countersinking tool (1) according to one of claims 1 to 11, characterised in that the main machining forces of the blade (7) can be transferred into the blade housing (3) via contact points of the blade (7) on the blade window (6).

13. Pressure medium-controlled countersinking tool (1) according to one of claims 1 to 12, characterised in that the still only remaining, radially acting degree of freedom influencing the countersinking result is eliminated with the centring device (21, 23, 42, 43).

14. Pressure medium-controlled countersinking tool (1) according to one of claims 1 to 13, characterised in that the centring bolt (23) can be replaced in the case of wear.

15. Pressure medium-controlled countersinking tool (1) according to one of claims 1 to 14, characterised in that additional, further centring devices for centring the blade (7) are arranged on the side surfaces of the blade window (6).