WO2013010518A2

WO2013010518A2 - Throttle flap device

Info

Publication number: WO2013010518A2
Application number: PCT/DE2011/001571
Authority: WO
Inventors: Peter Holzheu
Original assignee: Fey Lamellenringe Gmbh & Co. Kg
Priority date: 2011-07-15
Filing date: 2011-08-10
Publication date: 2013-01-24
Also published as: WO2013010518A3; DE102011107794A1

Abstract

The invention relates to a throttle flap device (1) having a housing (20), which has a flow duct (14) which conducts a fluid flow, and having a throttle flap (4), which is pivotable about a flap axis (2) and which, in a closed position, interacts with a throttle flap seat (10), for the purpose of setting a flow cross section for the fluid as a function of the rotational position of the throttle flap (4), wherein there is provided between the throttle flap seat (10) and the throttle flap (4) at least one sealing ring (8), the free ends (22, 24) of which form a ring discontinuity (26). The invention provides that those free ends (22, 24) of the sealing ring (8) which are arranged in the region of the ring discontinuity (26) overlap.

Description

throttle device

description

State of the art

The invention is based on a throttle valve device with a housing having a flow fluid flow channel and having a pivotable about a flap axis and in the closed position with a throttle seat cooperating throttle to adjust depending on the rotational position of the throttle a flow cross section for the fluid, wherein between the throttle seat and the throttle valve is provided at least one sealing ring, the free ends form a ring interruption, according to the preamble of claim 1.

Furthermore, the invention is based on a sealing ring for sealing between a throttle valve seat and a throttle valve throttle body, which has a housing having a fluid flow flow channel housing having, the throttle valve in the closed position with the throttle seat sealingly together and is pivotable about a flap axis to depending on adjust the rotational position of the throttle valve has a flow cross section for the fluid, wherein the free ends of the sealing ring form a ring break, according to the preamble of claim 18th

In the following, a "fluid" is to be understood as meaning both a gaseous medium and a medium present in liquid form.

A generic throttle valve device and a generic sealing ring are known for example from DE 10 2006 020 718 A1. The throttle valve device is arranged in the intake tract of an internal combustion engine. In some applications of such throttle devices, such as in an air flow meter of a λ-control or in an exhaust gas recirculation system of an internal combustion engine, it is important that the

CONFIRMATION COPY Throttle against the throttle seat in the Schiießstellung seals as leak-free as possible. For this purpose, the sealing ring is provided. On the other hand, the sealing ring should be seen in the circumferential direction have a certain freedom of movement to adapt to changing temperature conditions or tolerances of the throttle seat. Therefore, a ring interruption is provided in the known sealing ring, in which the ring ends are seen in the circumferential direction spaced from each other. Due to the distance between the ring ends of each other, however, an undesirable leakage flow is present even in the Schiießstellung the throttle.

The invention is based on the object, a throttle valve device or a sealing ring of the type mentioned in such a way that in the closed position of the throttle as low as possible leakage occurs.

According to the invention, this object is solved by the features of claim 1 and claim 18.

Disclosure of the invention

The invention relates both to a throttle device with arranged between a throttle seat and a throttle valve for sealing purposes sealing ring as well as a sealing ring for sealing between a throttle seat and a throttle valve body, wherein the free ends of the sealing ring form a ring break and in the field of ring interruption overlap.

Due to the overlapping of the ring ends, which prevents a straight flow through the sealing ring parallel to a central axis of the flow channel, the flow of the fluid is deflected at the overlap in the manner of a labyrinth seal at least once. This results in a throttling effect, which substantially reduces the leakage current. The measures listed in the dependent claims advantageous refinements and improvements of the protection claim 1 invention are possible.

Preferably, in the circumferential direction, the free ends of the sealing ring relative to each other at least limited mobility. Limited movable in this context means that the free ends of the sealing ring seen in the circumferential direction have a certain range of motion to changing temperature conditions or tolerances of the throttle valve seat or the inner or outer diameter of the sealing ring depending on its rotational position to the throttle seat or to be able to adapt to certain sealing requirements.

Particularly preferably, the sealing ring is an inwardly exciting sealing ring and arranged on the throttle valve seat on the radially inner peripheral surface of the flow channel. Consequently, the sealing ring is stationary and, for example, received in a circumferential annular groove of the radially inner peripheral surface of the flow channel with radial clearance. Inwardly exciting means in this context that the sealing ring clamps in the closed position of the throttle radially inward against the radially outer edge of the throttle valve. Then ensures the low leakage current, which infiltrates the outer diameter of the sealing ring in the groove bottom of the annular groove, that the sealing ring is pressed radially inwardly against the radially outer edge of the throttle valve, which improves the sealing effect against the throttle.

Since the protruding from the annular groove inner diameter of the sealing ring, which then forms the throttle seat, in an open position of the throttle preferably slightly smaller than the outer diameter of the outer edge of the throttle, move the ends of the sealing ring upon rotation of the throttle from one of the Closed position deviating position in the Closed position away from each other and at a rotation of the throttle valve from the closed position to a position deviating from the closed position towards each other. During rotation from a position deviating from the closed position into the closed position, the edge of the throttle flap, starting from a point contact, comes into line contact with the inner diameter of the sealing ring.

Alternatively, the sealing ring may be arranged an outwardly exciting sealing ring and the radially outer edge of the throttle valve, for example, characterized in that the sealing ring is received in a circumferential annular groove of the outer edge of the throttle with radial play. Then ensures the low leakage current, which infiltrates the inner diameter of the sealing ring in the groove bottom of the annular groove, that the elastic sealing ring is pressed radially outward against the throttle seat, which improves the sealing effect against the throttle seat.

Further, in this embodiment, since the outer diameter of the seal ring protruding from the annular groove is slightly larger than the inner diameter of the throttle valve seat at the radially inner peripheral surface of the flow passage in an opened position of the throttle valve, the ends of the seal ring move out of rotation upon rotation of the throttle valve from the closed position deviating position in the closed position towards each other and upon rotation of the throttle valve from the closed position to a position deviating from the closed position away from each other.

As with the embodiment described above, when rotating from a position deviating from the closed position to the closed position, the sealing ring, which co-rotates with the throttle flap, starts from a point contact in an, for example, circumferential line contact with the throttle valve seat. Preferably, the overlapping of the ends of the sealing ring is formed such that the ends of the sealing ring are arranged in a plane with the deviating from the overlap part of the sealing ring. This has the advantage that the receptacle for the sealing ring, for example, an annular groove is easy to produce.

Particularly preferably, the ends of the sealing ring in the overlapping region engage in a stepwise manner, wherein the gradation is formed perpendicular to the ring plane. To realize the ends of the sealing ring each have an axially projecting annular collar and a recess such that the annular collar of one end engages in the recess of the other end and the annular collar of the other end in the recess of one end, wherein seen in the circumferential direction in each case one End of an annular collar to one end of a recess has a distance which is dependent on the rotational position of the throttle valve.

This has the advantage that when viewed in the flow channel pending fluid pressure in a direction perpendicular to the ring plane, the collars are pressed against the recesses and thus adjusts a self-reinforcing sealing effect. In other words, the larger the fluid pressure difference between the throttle valve areas of the throttle valve, the higher the sealing effect.

In order to avoid that the stepped ends of the sealing ring can tilt against each other, e.g. if due to not exactly lying in a plane ends of the annular collar of one end contacted the annular collar of the other end and thereby a contraction of the sealing ring in the circumferential direction is prevented, the annular collars and / or the recesses on a run-on slope.

According to a further embodiment, the ends of the sealing ring can also engage in a wedge shape, ie the free ends of the sealing ring each have complementary wedge surfaces which can slide on one another, but are spaced apart in the ground state. Preferably, the sealing ring is produced by plastic bending and heat treatment of a straight rod-shaped element. Due to the bending creates a pressure zone below the neutral zone and a tensile zone above the neutral zone. Then measured perpendicular to the ring plane thickness of the sealing ring in the region of the pressure zone is greater than in the region of the tension zone.

Alternatively, the sealing ring can be produced by separating from a tubular element, wherein the end faces of the sealing ring are then machined and / or ground and / or honed or lapped, for example, and then lie in mutually parallel plane.

The throttle valve device according to the invention is preferably part of an air quantity measuring device for internal combustion engines or an exhaust gas recirculation device for internal combustion engines. In the first case, a fresh gas flow is controlled by the throttle valve device, in the second case an exhaust gas flow.

More specifically, it will be apparent from the following description of preferred embodiments.

drawing

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. In the drawing shows:

1 is a perspective view of an inventive

Throttle valve device according to one embodiment with a arranged on a radially outer edge of the throttle valve sealing ring in the closed position;

2 is a perspective view of the throttle valve device of Figure 1 in the open position.

3 shows an enlarged detail of the sealing ring; 4 shows a cross section of the sealing ring;

5 shows a perspective view of an inventive

Throttle valve device according to another embodiment with a arranged on a radially inner peripheral surface of the flow channel sealing ring in the closed position;

6 shows a perspective view of the throttle valve device of Figure 5 in the open position.

Description of the embodiments

In Figure 1, an embodiment of a throttle valve device 1 according to the invention in a closed position is shown, in which the pivotable about a damper shaft 2 throttle or a worn on its radially outer edge 6 sealing ring 8 with a throttle flap seat 10 at a radially inner Peripheral surface 12 of a flow channel 14 sealingly acts together. In the closed position, the two facing to a pressure side or facing away from this throttle valve surfaces 16, for example, perpendicular to the flow direction of the fluid or to a central axis 18 of the flow channel 14 are arranged. In order to better recognize the details, in particular the sealing ring 8, only part of the throttle valve 4 is shown.

The throttle valve device 1 is preferably part of an air quantity measuring device for controlling a fresh gas flow or an exhaust gas recirculation device for internal combustion engines for controlling an exhaust gas flow. Alternatively, the throttle valve device 1 can be used to control any flow of fluid flowing in a flow channel 14, such as, for example, liquids such as water, especially in the sanitary area. The flow channel 14 is then formed in a housing 20 of the corresponding device.

Depending on the rotational position of the throttle valve 4 relative to the throttle seat 10, a certain flow cross-section for the fluid in the flow channel 14th set. This flow cross section is equal to zero in the closed position shown in FIG. In Figure 2, an open position is shown, in which the throttle valve 4 occupies a certain angle relative to the flow direction of the fluid or the central axis 18 of the flow channel 14 and thus releases a certain flow cross-section. The flap axis 2 is preferably located in the plane of the throttle valve 4th

In the embodiment of Fig.1 and Fig.2, the sealing ring 8 is supported by the throttle valve 4 and therefore pivoted together with respect to the throttle seat 10, which is formed on the radially inner peripheral surface 12 of the flow channel 14 in the plane of the throttle valve 4.

The free ends 22, 24 of the sealing ring 8 form a ring interruption 26. It is essential that the free ends 22, 24 of the sealing ring 8 overlap in the region of the ring interruption 26. Due to the overlapping of the ends 22, 24, which prevents a straight flow through the sealing ring 8 parallel to a central axis 18 of the flow channel 14, the flow of the fluid is deflected at the overlap in the manner of a labyrinth seal at least once. In the closed position of the throttle valve 4, the overlap of the ends 22, 24 is perpendicular to the then merely imaginary flow of the fluid or perpendicular to the central axis 18 of the flow channel 14th

Particularly preferably, the ends 22, 24 of the sealing ring 8 in the overlapping region engage in a stepwise manner or in the manner of a rectangular joint, as shown in FIG. For this purpose, the ends 22, 24 of the sealing ring 8, for example, in each case an axially projecting annular collar 28, 28 'and a recess 30, 30' in such a way that the annular collar 28 of the one end 22 in the recess 30 of the other end 24 and the annular collar 28th 'engages the other end 24 in the recess 30' of the one end 22, wherein seen in the circumferential direction one end of a collar 28, 28 'to one end of a recess 30, 30' each have a distance X, which depends on the rotational position of the throttle 4 is. Furthermore, the overlap of the ends 22, 24 of the sealing ring 8 is preferably formed such that the ends of the sealing ring 22, 24 are arranged in a plane with the deviating from the overlap part of the sealing ring 8. Thus, all sections of the sealing ring 8 are in a single ring plane. Alternatively, the region of the overlap could also be arranged outside the plane of the part of the sealing ring 8 deviating from the overlap.

In the embodiment of Figure 1 and Figure 2, the sealing ring 8 is a radially inwardly exciting sealing ring 8 and, for example, received in a circumferential annular groove 32 of the outer edge 6 of the throttle valve 4. In this case, the sealing ring 8 protrudes from the annular groove 32 a bit far radially outward. Furthermore, in the open or unloaded position according to FIG. 2, the outer diameter of the sealing ring 8 projecting from the annular groove 32 is preferably slightly larger than the inner diameter of the throttle valve seat 10 on the radially inner peripheral surface of the flow channel 14. In addition, in the open or unloaded position according to FIG 2, the inner diameter of the sealing ring 8 in the open or unloaded position of the throttle valve 4 according to Figure 2 slightly larger than the outer diameter of the groove bottom of the annular groove 32. This can occur, the unloaded sealing ring 8 has a corresponding geometry or bias.

As a result, and due to the elasticity and the preferably stepped executed ring interruption 26, the ends 22, 24 of the sealing ring 8 can move towards each other during a rotation of the throttle valve 4 from an open position according to Figure 2 in the closed position according to Figure 1 to to reduce the distance X (see Fig.3). At the same time in the closed position, the inner diameter of the sealing ring 8 is urged against the groove bottom of the annular groove 32 at the radially outer edge 6 of the throttle valve 4 substantially without a gap.

Upon rotation of the throttle valve 4 from the closed position to an open or unloaded position as shown in FIG. 2, the ends 22, 24 move of the sealing ring 8, however, due to the elastic properties of the sealing ring away from each other again to increase the distance X. At the same time removed in the open position, the inner diameter of the sealing ring 8 from the groove bottom of the annular groove 32 at the radially outer edge 6 of the throttle valve 4 slightly.

The distance X may be greater than zero but also equal to zero in the closed position of the throttle valve 4 according to Figure 1, in the open or unloaded position, it is always greater than zero. During rotation from an open position to the closed position of the co-rotating with the throttle valve 4 8 gets from a point contact in the region of the flap axis 2 in an annular circumferential line contact with the throttle valve seat 10th

The stepped execution of the overlap of the free ends 22, 24 of the sealing ring 8 in combination with the distance X according to Figure 3 has the result that seen in the circumferential direction, the free ends 22, 24 of the sealing ring 8 are relatively limited movable. The limitation of the circumferential mobility of the sealing ring 8 is given by the contact of the ends of the annular collars 28, 28 'with the ends of the associated recess 30, 30 "(see Figure 3).

In order to avoid that the stepped ends 22, 24 of the sealing ring 8 can tilt against each other, e.g. if due to not exactly lying in the plane of the ring ends 22, 24, the annular collars 28, 28 'can not cooperate with the associated recesses 30, 30' together but contact each other end face and thereby compression of the sealing ring 8 is prevented in the circumferential direction, have the annular collars 28th , 28 'or the recesses 30, 30' preferably each have a run-on slope 34, as Figure 3 shows.

According to an embodiment shown in Figure 5 and Figure 6, the sealing ring 8 is an outwardly exciting sealing ring and the throttle valve seat 10 on the radially inner peripheral surface 12 of the flow channel 14 also in one stationary annular groove 32 received perpendicular to the central axis 18. Furthermore, the outer diameter of the sealing ring 8 in the open or unloaded position of the throttle valve 4 according to FIG. 6 is preferably slightly smaller than the diameter of the annular groove 32 on the groove base. In this case, the sealing ring 8 protrudes with its inner diameter a little way out of the annular groove 32 radially inward, wherein the protruding from the annular groove 32 inner diameter of the sealing ring 8, which then forms the throttle seat 10, in the open or unloaded position of the throttle valve 4 shown in FIG .6 is preferably slightly smaller than the outer diameter of the radially outer edge 6 of the throttle valve 8. This may occur, the sealing ring 8 has a corresponding geometry or bias.

The sealing ring is formed as in the preceding embodiment or as shown in Figure 3 and Figure 4. Then the ends 22, 24 of the sealing ring 8 move away from an open position according to Figure 6 in the closed position according to Figure 5 away from each other with a rotation of the throttle valve 4, wherein the outer diameter of the sealing ring 8 increases and radially outward against the groove bottom the annular groove 32 is preferably pressed substantially without gaps in order to increase the sealing effect. At the same time, the distance X is increased (see FIG. 3).

When the throttle valve 4 is rotated from the closed position according to FIG. 5 into the open or unloaded position according to FIG. 6, the ends 22, 24 of the sealing ring 8 move towards each other, whereby the outer diameter of the sealing ring 8 moves from the groove bottom of the annular groove 32 moved radially inward and the distance X is reduced, (see Fig. 3).

During the rotation from an open position according to FIG. 6 into the closed position according to FIG. 5, the radially outer edge 6 of the throttle valve 4 comes into line contact with the inner diameter of the sealing ring 8 starting from a point contact in the area of the flap axis 2. Preferably, the sealing ring 8 is produced by plastic bending and heat treatment of a straight rod-shaped element. Due to the bending creates a pressure zone below the neutral zone and a tensile zone above the neutral zone. Then measured perpendicular to the ring plane thickness of the sealing ring 8 in the region of the pressure zone is greater than in the region of the tension zone. Alternatively, the sealing ring 8 can be made by vertically separating rings of pipe, wherein the end faces of the sealing ring 8 are then machined and / or ground and / or honed or lapped, for example, and then lie in mutually parallel plane. The material used for the sealing ring 8 is preferably a spring steel strip C75, CK60 or a chrome nickel steel no. 1.4310, no. 1.4571 or no. 1.4980.

4 shows a cross section through a sealing ring 8 as used in the embodiments according to Fig.1 / Fig.2 and Fig.5 / Fig.6. Accordingly, the inner diameter 36 and the outer diameter 38 are preferably convexly convex.

According to a further, not shown embodiment, the ends 22, 24 of the sealing ring 8 also engage wedge-shaped, ie the free ends 22, 24 of the sealing ring 8 each have complementary wedge surfaces which can slide on each other, but are spaced apart in the ground state. Last but not least, any geometry with an undercut cross-section is conceivable in order to realize an overlap of the ends 22, 24 of the sealing ring 8 in the region of the ring interruption. LIST OF REFERENCE NUMBERS

throttle device

damper shaft

throttle

radially outer edge

seal

Drosselklappelsitz

radially inner peripheral surface

flow channel

throttle surfaces

central axis

casing

The End

ring interruption

'28' waistband

, 30 'recess

ring groove

starting slope

Inner diameter

outer diameter

Claims

claims

1. Throttle device (1) with a Ruidströmung a conducting flow channel (14) having housing (20) and with a closed position with a throttle valve seat (10) sealingly together and about a flap axis (2) pivotable throttle valve (4) to depending on the rotational position of the throttle valve (4) to set a flow cross-section for the fluid, wherein between the throttle valve seat (10) and the throttle valve (4) at least one sealing ring (8) is provided, the free ends (22, 24) form a ring interruption (26) , characterized in that in the region of the ring interruption (26) arranged free ends (22, 24) of the sealing ring (8) overlap.

2. Throttle valve device according to claim 1, characterized in that seen in the circumferential direction, the free ends (22, 24) of the sealing ring (8) relative to each other are at least limited mobility.

3. throttle valve device according to claim 2, characterized in that the sealing ring (8) is arranged an inwardly exciting sealing ring and the throttle valve seat (10) on the radially inner peripheral surface (12) of the flow channel (14).

4. throttle valve device according to claim 3, characterized in that the inwardly exciting sealing ring (8) in a circumferential annular groove (32) of the radially inner peripheral surface (12) of the flow channel (14) is received with radial clearance.

5. throttle valve device according to claim 4, characterized in that the ends (22, 24) of the sealing ring (8) during a rotation of the Throttle valve (4) from a position deviating from a closed position to the closed position away from each other and to move towards each other during a rotation of the throttle valve (4) from the closed position to a position deviating from the closed position.

6. throttle valve device according to claim 2, characterized in that the sealing ring (8) an outwardly exciting sealing ring and the radially outer edge (6) of the throttle valve (4) is arranged.

7. throttle valve device according to claim 6, characterized in that the outwardly exciting sealing ring (8) in a circumferential annular groove (32) of the radially outer edge (6) of the throttle valve (4) is received with radial play.

8. Throttle valve device according to claim 7, characterized in that the ends (22, 24) of the sealing ring (8) upon rotation of the throttle valve (4) from a position deviating from the closed position to the closed position toward each other and upon rotation of the throttle valve (4) move away from the closed position to a position deviating from the closed position.

9. throttle valve device according to one of the preceding claims, characterized in that the overlap of the ends (22, 24) of the sealing ring (8) is formed such that the ends (22, 24) of the sealing ring (8) in a plane with the of the overlap deviating part of the sealing ring (8) are arranged.

10. Throttle valve device according to one of the preceding claims, characterized in that the ends (22, 24) of the sealing ring engage in a stepwise manner, wherein the gradation formed perpendicular to the ring plane is.

1 1. Throttle valve device according to claim 10, characterized in that the ends (22, 24) of the sealing ring in each case an axially projecting annular collar (28, 28 ') and a recess (30, 30'), such that the annular collar (28 ) of the one end (22) in the recess (30) of the other end (24) and the annular collar (28 ') of the other end (24) in the recess (30') of the one end (22) engages, wherein in the circumferential direction seen in each case one end of an annular collar (28, 28 ') to one end of a recess (30, 30') has a distance (X) which is dependent on the rotational position of the throttle valve (4).

12. Throttle valve device according to claim 11, characterized in that the annular collars (28, 28 ') and / or the recesses (30, 30') have a run-on slope (34).

13. Throttle valve device according to one of claims 1 to 9, characterized in that the ends (22, 24) of the sealing ring (8) engage in a wedge-shaped manner.

14. Throttle valve device according to one of the preceding claims, characterized in that the sealing ring (8) is produced by bending a straight rod-shaped element, wherein the thickness of the sealing ring (8) in the region of the pressure zone is greater than in the region of the tension zone.

15. Throttle valve device according to one of claims 1 to 13, characterized in that the sealing ring (8) is made by separating from a tubular element, wherein the end faces of the sealing ring (8) are arranged in mutually parallel plane.

16. Air quantity measuring device for internal combustion engines comprising at least one throttle valve device (1) according to one of the preceding claims.

17. Exhaust gas recirculation device for internal combustion engines comprising at least one throttle valve device (1) according to one of claims 1 to 15.

18 sealing ring for sealing between a throttle seat (10) and a throttle valve (4) of a throttle device (1) having a fluid flow conducting flow channel (14) exhibiting housing (20), wherein the throttle valve (4) in the closed position with the throttle seat (10) acts sealingly together and about a flap axis (2) is pivotable to adjust depending on the rotational position of the throttle valve (4) has a flow cross section for the fluid, wherein the free ends (22, 24) of the sealing ring (8) has a ring interruption ( 26), characterized in that in the region of the ring interruption (26) arranged free ends (22, 24) of the sealing ring (8) overlap.

19. Sealing ring according to claim 18, characterized in that seen in the circumferential direction, the free ends (22, 24) of the sealing ring (8) relative to each other are at least limited mobility.

20. Sealing ring according to claim 18 or 19, characterized in that the overlap of the ends (22, 24) of the sealing ring (8) is formed such that the ends (22, 24) of the sealing ring (8) in a plane with that of the overlap deviating part of the sealing ring (8) are arranged.

21. Sealing ring according to one of claims 18 to 20, characterized in that the ends (22, 24) of the sealing ring (8) interlock stepwise, wherein the gradation is formed perpendicular to the ring plane.

22. Sealing ring according to one of claims 18 to 21, characterized in that the ends (22, 24) of the sealing ring in each case an axially projecting annular collar (28, 28 ') and a recess (30, 30'), such that the Annular collar (28) of one end (22) in the recess (30) of the other end (24) and the annular collar (28 ') of the other end (24) in the recess (30') of the one end (22) engages, wherein in the circumferential direction each one end of a collar (28, 28 ') to one end of a recess (30, 30') has a distance (X) which is dependent on the rotational position of the throttle valve (4).

23. Sealing ring according to claim 22, characterized in that the annular collars (28, 28 ') and / or the recesses (30, 30') have a run-on slope (34).

24. Sealing ring according to one of claims 18 to 20, characterized in that the ends (22, 24) of the sealing ring (8) engage in a wedge-shaped manner.

25. A method for producing a sealing ring according to one of claims 18 to 24, characterized in that the sealing ring (8) is produced by plastic bending and heat treatment of a straight rod-shaped element.

26. A method for producing a sealing ring according to one of claims 18 to 24, characterized in that the sealing ring (8) is produced by separating from a tubular member and the ends and end faces of the sealing ring (8) machined and / or ground and / or or to be honed or lapped.