JP6092461B2 - Honing finishing method and honing finishing tool - Google Patents

Description

  The present invention relates to a honing finishing method for machining the inner surface of a bore of a workpiece by at least one honing finishing operation described in the premise of claim 1, and a honing finishing method described in the premise of claim 6 The invention relates to a honing finish tool that can be used to carry out. A preferred field of application is the honing finish of cylinder faces in the manufacture of cylinder blocks or cylinder liners for reciprocating piston engines.

  The cylinder block (cylinder crankcase) of an internal combustion engine or other reciprocating piston engine or the cylinder face of a cylinder liner is subjected to severe tribological stress during operation. Thus, during the manufacture of a cylinder block or cylinder liner, the cylinder face is guaranteed to be adequately lubricated by a lubricant film under all operating conditions and the frictional resistance between the parts moving against each other is kept as small as possible. Must be machined as follows.

  Finish machining that determines the quality of the inner surface to which such tribological stress is applied is generally performed by a suitable honing method, which typically includes multiple successive honing operations. . The honing finish is a cutting process using a geometrically indefinite cutting edge. During the honing operation, the expandable honing tool is combined with reciprocating motions while moving up and down or back and forth within the bore to be machined to produce a reciprocating motion of the bore in the axial direction at the number of reciprocating cycles. Rotate to produce rotational movement at a given number of rotations. The body of cutting material attached to the honing finish tool is pressed against the inner surface to be machined by the infeed system, the infeed system having an infeed force acting radially on the tool axis. During the honing finish, a cross-grinding pattern is created on the inner surface with crossed finish marks that are characteristic of honing finish machining and are also referred to as “honed finish grooves”.

  In order to achieve low levels of friction, low levels of wear and low oil consumption as the requirements for economic and environmental harmony of the engine and optimization of the piston / piston ring tribological system increase, cylinder faces Is particularly important. The frictional portion of the piston group can be up to 35%, and therefore friction reduction in this region is desirable.

  Various schemes have been pursued to reduce engine mechanical losses. These include, among other things, the use of a thermally sprayed cylinder face, the use of a coated piston ring, and the development of a particularly optimized honing surface.

  An increasingly important technique in reducing friction and wear is to avoid or reduce cylinder distortion or deformation of the engine block (cylinder crankcase) during assembly and / or operation. After conventional honing machine operations, the cylinder bore typically has a bore shape that deviates as little as possible from the ideal cylindrical shape, eg, deviates by only a few micrometers at most. However, during engine assembly or operation, significant shape errors can occur, which can be as high as a few hundredths of a millimeter and impair engine performance. There are various causes of distortion or deformation. Such causes include static or virtually static thermal and / or mechanical or dynamic loads. The configuration and design of the cylinder block also affects the deformation tendency. The sealing function of a piston ring package is typically exacerbated by such deformations that can be difficult to control, which can result in increased blow-by, oil consumption and even friction.

  In order to alleviate problems due to distortion during assembly or in certain operating conditions, for example in DE 2810322 (C2) the following deformation is simulated by the cylinder head: It was proposed to use a tension adjustment device to deform the engine block for honing finishing machining. Next, in a reinforced state corresponding to the condition that exists after assembly, honing finish machining is performed to produce a cylindrical bore shape, which is then again defined after assembly. It has become.

  During finish machining, reversing cylinder distortion (making the error negative shape) ensures that the ideal shape is made or nearly guaranteed after assembly of the engine or in the operating state. The technique is a technique called shape honing. In this case, a bore shape deviating from the cylindrical shape in a defined manner, for example a clover shape, is produced on the unreinforced workpiece by honing. Such a bore shape is generally asymmetric. This is because the deformation of the cylinder block is generally not symmetrical either. In operation, the ideal cylindrical shape as possible is designed so that the piston ring package can provide a good seal over the entire circumference of the bore. Various forms of shape honing are described, for example, in EP 1790435 (B1) and the prior art cited therein.

German Patent No. 2810322 (C2) specification EP 1790435 (B1) Specification

  The problem to be solved by the present invention is to implement a honing method in the form of a problem and to implement this honing method so that it is possible to produce a reciprocating piston engine with improved properties in terms of friction loss, oil consumption and blow-by. It is to provide a honing finishing tool that can be used to do so.

  In order to solve this problem, the present invention provides a honing method with the features of claim 1. Furthermore, a honing tool with the features of claim 6 that can be used within the scope of a honing method is provided.

  Advantageous embodiments are described in the dependent claims. The full description of the claims is understood by reference to the content of the specification.

  In the honing finish method, a bowl-shaped bore, that is, a bore having a bowl shape is formed. A “saddle-shaped bore” immediately follows the bore inlet, a first bore section with a first diameter, a second bore having a second diameter greater than the first diameter and located away from the bore inlet. Two bore sections and a transition section continuously transitioning from the first diameter to the second diameter and located between the first bore section and the second bore section. The first bore section and the second bore section generally have a cylindrical basic shape and are located coaxially with respect to each other. The transition section may be partly conically shaped, such that its transition section towards the outer bore section may merge into an adjacent bore section, each with a suitable radius. It has.

  Given the appropriate configuration of the saddle-shaped macro shape, significant advantages can be obtained with respect to reduced friction, reduced blow-by, and reduced oil consumption. Furthermore, it is possible to obtain a positive effect on the wear resistance of the piston ring package and the generation of noise during operation. A significant portion of the combustion within the internal combustion engine occurs at a relatively narrow or narrow first bore section near the bore inlet, or “bottleneck”. Probable supply of oil within this category may cause problems with emissions and oil consumption. Within this narrow first bore section, the piston ring annular package has a relatively high edge stress, making it easy to perform its conventional functions (especially sealing against combustion gases and scraping the oil film during return movement). can do. Due to the pressure wave of combustion, the piston is accelerated in the first bore section and reaches a transition section that gradually increases in diameter. Within the transition section, the piston ring tension decreases with increasing diameter. However, a considerably higher piston speed already exists here and the internal pressure in the cylinder space is reduced, so that blow-by, oil consumption values and engine emission noise (noise emissions) are not adversely affected. With a suitable radius between the transition section and the adjacent first and second bore sections, a gentle entry and exit of the piston ring can be achieved at the transition section, thus avoiding ring wear or engine seizure. Can do. During downward movement, the annular package reaches its lowest tension as it enters the second bore section after passing through the transition section, and therefore friction loss automatically occurs when the piston reaches its maximum speed. Decrease.

  Particularly suitable for this purpose in the context of a honing finish method that allows obtaining a saddle bore with surface structure optimums for use, and in the context of the honing finish tool configuration, an “annular tool” is referred to herein. A honing finishing tool, also called a honing tool, is used. An “annular tool” in the context of the present application has at least one annular cutting group with three or more radially feedable cutting material bodies, which are the tools of the honing tool. It is distributed around the circumference of the body and is configured as a honing finishing segment, which is relatively wide in the circumferential direction of the honing finishing tool and in the axial direction of the honing finishing tool It is relatively narrow. The axial length of the honing finish segment measured in the axial direction of the honing tool is in this case smaller than the width measured in the circumferential direction, and the axial length of the cutting area with the cutting material body is the honing finish. It is smaller than the effective outer diameter of the tool.

  When at least three honing finish segments are provided, the machining force can be easily distributed over the effective outer diameter area of the honing tool available due to radial feed and relatively uniformly distributed over the entire circumference. . For example, the cutting group can be provided with exactly three, exactly four, exactly five or exactly six honing finish segments of the same or different peripheral widths. Although seven or more honing segments in the cutting group are possible, these honing segments are generally not required because they make the configuration more complex. In some cases, as an option, the honing tool may be in time even if it only has two honing segments.

  The effect that can be achieved by being able to feed in the radial direction (due to the displacement of the radial honing segment during feeding) is independent of the diameter setting of the engagement conditions between the cutting material body and the bore inner surface. The fact is that it remains practically constant. Non-uniform wear can be avoided by avoiding tilting of the cutting material body during radial feeding.

  The means described above can have a positive effect on the surface quality that can be achieved individually and in combination, in particular with regard to the uniformity of the surface quality across different bore sections.

  The axial length of the honing finish segment should be, for example, less than 30% of the effective outer diameter of the honing finish tool, in particular 10% to 20% of this outer diameter. In the case of an annular tool for machining a typical cylinder bore in a passenger car or truck engine block, the axial length may be in the range of 5 mm to 20 mm, for example. Based on the bore length of the bore to be machined, the axial length is typically less than 10% of this bore length. If the upper limit is significantly exceeded, the axial continuation of these contours or the possibility of creating these contours is generally impaired. In addition, a small axial length is advantageous for the purpose of generating sufficient surface pressure for machining. On the other hand, the minimum length in the axial direction is advantageous for the purpose of allowing a honing finish overrun to machine the bore end and limiting the tendency of the honing tool to tilt.

  This type of annular tool should be used with a honing tool having a honing wheel that is relatively long in the axial direction but relatively narrow in the circumferential direction in order to obtain a slight form error in the honed bore. . Annular tools are particularly easily adapted to machining of bore shapes or bore shapes that have bore diameters that generally vary considerably in the axial direction. Within the ring cutting group, cutting materials (bonded cutting crystal grains of appropriate grain size, density and hardness) are concentrated in a relatively narrow ring in the axial direction. In this case, typically, More than half of the circumference of the annular cutting group is occupied by the cutting means, thus effectively contributing to material removal.

  Compared to the effective outer diameter of the honing tool, the cutting area in which one or more annular cutting groups are located is short or narrow in the axial direction, so that a contour extending in the axial direction is produced. And / or a continuation is possible.

  Compared to conventional honing stones, the annular cutting group has a relatively narrow shaft of the conventional honing finishing tool between the cutting material body and the bore inner surface in the axial section covered by the annular cutting group. A distinction is made in that there is a substantially wider contact surface than in the case of direction segments. In some embodiments, the annular cutting group occupies more than 60%, in some cases more than 70% or more than 80% of the circumference of the honing finish tool by the cutting means.

  The cutting group is preferably arranged in the vicinity of the end far from the spindle of the tool body so that the cutting group is exclusively located in the half that is far from the spindle of the tool body. If multiple annular cutting groups are provided, this condition applies to any cutting group. The configuration near the end far from the spindle allows machining operations with, among other things, very small honing finish overruns.

  During machining by honing, the stroke position of the honing tool in the bore can be used as a command variable, the purpose of which is to determine the preload pressure or feed force as a function of the stroke position of the annular cutting group with high local resolution. It is to decide. The result is a bore with a variable contour in the axial direction that follows the contour that has already been pre-made and changes in the axial direction without undesired contact pressure or force peaks due to the feedable annular cutting group. Is possible. If an annular tool is used, the work should be carried out in all axial regions of the bore with substantially the same overlap, so that if required, a very uniform roughness image Or a surface structure can be made. If an annular tool is used, the operation can optionally be carried out with a very low honing finish overrun at the axial end of the bore without any problems with non-uniform wear of the cutting body. it can.

  This operation is preferably performed by an electromechanical cutting group feed system. As a result, in contrast to hydraulic expansion, it is possible to precisely determine the amount of feed movement in advance (movement amount control), so that an axial contour can be created in a specific way and / or predetermined The axial contour of can be traced precisely.

  One or more sensors of the diameter measurement system may be placed on the honing tool, thus allowing in-process diameter measurements. For example, the measurement nozzles of the pneumatic diameter measurement system may each be attached to the tool body between adjacent honing finish segments. This means that the accuracy of the bore contour that can be achieved can be improved.

  The use of an annular tool ensures uniform wear of the cutting material body as well as very good shape values and uniform surface roughness of the bore over the entire surface life of the annular cutting group.

  Various configurations of the annular tool are possible and the user can choose from these forms depending on the machining task to be performed.

  In some embodiments, the annular tool has a single annular cutting group, and the honing finish segments of such a cutting group can be fed or pulled back radially by a single common feeding system. Annular cutting groups typically include three or more, typically no more than six honing finish segments that are uniformly or non-uniformly distributed throughout the perimeter of the honing tool. Have. The single annular cutting group is preferably arranged in the vicinity of the free end far from the spindle of the tool body, for example flush with the end side far from the spindle. This type of configuration is particularly suitable for machining cylinder bores with reduced honing finish overruns. This kind of restriction in machining occurs, for example, in the case of a blind bore or in the case of a cylinder bore of an engine block for a monoblock engine or a V-type engine.

  It is also possible for the annular cutting group to have two groups of honing finishing segments that can be fed separately and independently, in which case the honing finishing segments belonging to these groups are arranged alternately in the circumferential direction. . This has the advantages of a single annular cutting group (for example, for machining bores with a shortened honing finish overrun) and the dual feed of two groups of honing segments that are independent of each other. It is possible to combine them. With this type of tool, two consecutive honing operations can be performed with different cutting materials without any intermediate modification of the tool. The honing segments that belong to one group of honing segments usually have the same cutting layer, which groups have different cutting layers, for example diamond layers of different grain sizes.

  The annular tool is disposed in an axially offset manner with respect to the first annular cutting group and the first annular cutting group, and at least one first tool capable of being fed independently from the first annular cutting group. It is possible to have two annular cutting groups. This means that two consecutive honing operations can also be performed with different cutting materials without any intermediate changes in the tool. In this case, in both honing finishing operations, different cutting materials are axially offset with respect to each other and each is distributed into at least two annular cutting groups that can span most of the circumference of the honing cutting tool. A particularly high removal capacity or a relatively short honing time is possible. This type of annular tool can be used for all bores that allow sufficient honing finish overrun. With two or more annular cutting groups, pulsation windows or transverse bore bridging or any form of bore interruption is also possible in a particularly simple manner. Such an annular tool preferably has exactly two annular cutting groups, so that it can be used flexibly despite a single configuration.

  In a preferred embodiment, an integral multi-axis movable joint, such as a spherical joint or a cardan joint, is provided on the tool body. Thereby, machine position errors and / or bore core offsets can be compensated without changing the bore position. An exemplary embodiment in which no joint is provided is also feasible. This type of annular tool can be rigidly coupled to a honing spindle or rigidly coupled to a drive rod that is rigidly coupled to the honing spindle.

  The bore shape of the bore can be made by any suitable chip removal machining method, for example by precision turning (high precision spindle), i.e. by machining with a geometrically determined cutting edge or by honing. Once this has been done, one or more honing operations may be performed, the goal being to obtain the final desired bore geometry with the appropriate surface structure.

  A bore with a cylindrical bore shape is preferably made initially by precision turning or honing, and then in hoisting honing operations honing finish removal is performed that changes the hoisting bore shape in the axial direction. Made by. Compared to precision turning, the surface can be produced with a particularly uniform surface quality without peripheral marks by honing. The self-acting effect of the cutting material body also contributes to the uniformity of the surface quality. In the case of honing, continuous process monitoring is possible.

  In an alternative method, an extended honing tool having at least one annular cutting group, i.e. an annular tool, is used during the saddle honing operation. In this case, the honing finish segment of the cutting group follows the shape of the saddle according to the stroke position, and is fed radially outward by a movement and / or force control method in the downward stroke, and in the upward stroke, the honing finish segment is moved to the stroke position. Retract in the radial direction according to the heel shape. This machining variant creates a relatively smooth contour shape from the beginning of the transition segment, which is particularly difficult to machine.

  Further, as a modification, an extended honing finishing tool equipped with a honing grindstone is used during the honing finishing work, and its length exceeds 50% of the length of the bore. The length of the honing grindstone is preferably, for example, 50% to 80% of the length of the bore.壜 During the honing operation, in the first stage, the honing finish tool is then moved up and down or back and forth between the upper and lower reversal positions at the first stroke position to initially adjust the length of the bore. Use a cylindrical shape throughout. Next, in the second stage, the upper reverse position is changed in small increments in the direction of the lower reverse position, that is, by a plurality of strokes, and therefore the stroke length is gradually reduced. As a result, the stroke position is shifted in the direction of the second stroke position located near the second bore segment. Next, in a third stage, the honing finish tool is moved back and forth at the second stroke position. In this alternative method, the basic shape of the transition section is made substantially during the second stage of the gradual shift of the stroke position and the reduction of the stroke height, in this case the second bore section. An increase in diameter is also made simultaneously and in a third stage.

  When the honing finish operation is performed by a honing tool having a relatively long honing wheel, a relatively rough surface structure with a profile that is approximately the same as the sawtooth profile can be created in the transition section. Therefore, in order to obtain the desired uniform surface structure in the transition section, a smoothing honing operation that smoothes the bore contour shape of the transition section or region is preferably performed after the heel honing operation, An annular tool, i.e. an extended honing tool with at least one annular cutting group, is used in the smoothed honing operation. With the annular tool, the grooves or burr of the transition section can be eliminated and the round of the transition section can be rounded (rounded).

  During the smoothing honing operation, it has proved advantageous if the cutting material body of the annular cutting group is pressed against the inner surface of the bore with a constant feed force. This is achieved in some alternative methods by using a honing machine (sometimes called a honing machine) with a hydraulic feed system for the annular tool. The continuation of the profile of the bowl bore by the honing finish segment of the annular tool can already be made in this case based on the flexibility gained by the design of the hydraulic expansion.

  The present invention also relates to a honing tool that is particularly suitable for carrying out a honing method, but can also be used in other honing methods that are not in accordance with the present invention.

  The invention also relates to a workpiece having at least one bore with a honing finished inner surface, wherein the bore is a saddle bore, the saddle bore following the bore inlet and having a first diameter. A first bore section provided, a second bore section having a second diameter greater than the first diameter and located away from the bore inlet, and continuously from the first diameter to the second diameter There is a transition section that is transitioned and located between the first bore section and the second bore section. The workpiece is machined using the honing tool of the present invention.

  In particular, the workpiece may be a cylinder block or cylinder liner for a reciprocating piston machine. The reciprocating piston machine may be, for example, an internal combustion engine (combustion engine) or a compressor.

It is a schematic longitudinal cross-sectional view of the vertical cylinder bore of an engine block. FIG. 2A is a longitudinal cross-sectional view (2A) of an embodiment of an annular tool in which a single extension of a single annular cutting group is performed and a cross-sectional view (2B) of the cutting group. FIG. 6 is a longitudinal cross-sectional view (3A) of an embodiment of an annular tool in which double expansion of a single annular cutting group is performed and a cross-sectional view (3B) of the cutting group. FIG. 4A is a longitudinal cross-sectional view (4A) of an embodiment of an annular tool in which double expansion is performed with two annular cutting groups arranged one above the other and a cross-sectional view (4B) of one of the cutting groups. FIG. 3 is a schematic longitudinal cross-sectional view of a bore machined by a honing finish tool having a relatively long honing wheel. FIG. 4 schematically shows the stroke position of a honing finish tool having a long honing wheel as a function of honing finishing time t during a honing finishing operation. It is a measurement figure of the round outline of a saddle-shaped cylinder after use of an annular tool. 4 is a schematic diagram showing the dependence of stroke position HP (solid line) and extended position AP (dashed line) as a function of honing finish time t in the second exemplary embodiment.

  The following is a honing finishing method and honing that can be used in connection with embodiments of the present invention during material removal machining with one or more bores that now have a trough macro shape in the end machining state 2 is a description of an exemplary embodiment of a finishing tool.

  FIG. 1 is a schematic longitudinal sectional view of one such bowl-shaped bore 110 of a workpiece 100 in the form of an engine block (cylinder crankcase) for an internal combustion engine. The bore is rotationally symmetric with respect to its bore axis 112, which bore extends over a bore length L from the bore inlet 114 facing the cylinder head to the opposite bore outlet 116 in the mounted state. The bore can be divided into three mutually adjacent sections of different function, these sections being slidable together, i.e. without the formation of steps or edges.

  The first bore section 120 at the inlet end has a first diameter D1 and a first length L1. The second bore section 130 located at the opposite outlet end extends over a second length L2, and the inner diameter (second diameter) D2 of this second bore section is the first diameter. Greater than D1. A partially conical transition section 140 is disposed between the first bore section 120 and the second bore section 130, where the transition section 140 is a continuous transition from a first diameter to a second diameter. Has occurred. A first deformation R1 is formed between the substantially conical portion in the center of the transition section and the first bore section, and a second radius R2 is formed between the transition section and the second bore section. Has been. The radii R1 and R2 may be substantially the same, but the first diameter may be smaller or larger than the second diameter.

  For a typical bore geometry, the first length L1 may be 15% to 40% of the bore length L, for example. The second length L2 is typically larger than the first length, and in many cases is 40% to 60% of the bore length L. The transition segment is usually relatively short relative to the adjacent bore segment. The representative third length L3 may be in the range of 5% to 20% of the bore length L. Deviations from these geometric ratios are also possible.

  The difference in diameter between the first diameter D1 and the second diameter D2 is well outside the tolerances specific to honing finish machining, and in the case of a cylinder shape, a range of the order of up to 10 μm (based on diameter) Is in. In the case of the absolute value of the inner diameter of the order of 70 mm to 150 mm, the difference in diameter may be, for example, 20 μm to 90 μm.

  The radii R1, R2, the length of the outer bore section and the transition section, and the tangent angle T between the bore axis and the transition section tangential, low blow-by, low oil consumption and low piston ring wear are typical of engine operation. It should be optimized to occur in the state.

  As a result of the bore being in the shape of a saddle, the bore is relatively narrow (thin) in the region near the inlet, so the piston ring of the piston moving in the bore is subject to high edge stresses. It is pressed against the bore inner surface 118. As a result, a positive seal is achieved where combustion occurs primarily and where high pressure occurs, and the oil film is scraped off during the downward stroke. The piston accelerated by the combustion moves in the direction of the bore inlet and the piston ring first runs through the transition section where the inner diameter increases gradually (partially) and then runs through the second bore section. . The piston ring may loosen gradually within the transition section, and the seal remains to a sufficient extent as the pressure differential drops at the piston ring. At the beginning of the second bore section, the ring package reaches its lowest stress state, and therefore friction loss decreases, more precisely near the maximum piston speed, due to the reduced edge stress. Then, during the upward stroke, the edge stress increases again as soon as the piston ring reaches the exit radius of the transition section and runs through the transition section in the direction of the first bore section.

  A precision machining process that is capable of making such a bore with high quality and economy with respect to the macro shape (saddle shape) as well as the inner surface of the bore that is tribologically stressed is, in an embodiment of the present invention, at least one honing finish operation. In such honing operations, a particular configuration of honing tool, also referred to herein as an “annular tool”, is used. The annular tool has at least one cutting group that is annularly attached to the tool body and includes a cutting material body, the cutting material body being arranged distributed around the periphery of the tool body. The body can be fed or retracted radially by an associated feeding system. The body of the cutting material is designed as a honing finish segment, the width of these honing finish segments being significantly greater in the circumferential direction than in their length when viewed in the axial direction. The cutting material body responsible for removing material from the work piece is concentrated in a relatively narrow area (ring of the cutting group) in the axial direction and occupies a relatively large portion around the honing finishing tool. As a result, bore shapes in which bore sections having different diameters are located adjacent to each other in the axial direction can be produced with a relatively high material removal capability.

  FIG. 2A, which is a partial view of FIG. 2, is a longitudinal cross-sectional view of an embodiment of an annular tool 200 that includes a single annular cutting group 220 and is expanded once. FIG. 2B is a cross-sectional view of the cutting group. The annular tool 200 has a tool body 210 defining a tool axis 212 that simultaneously rotates on the rotational axis of the ring tool during honing finish machining. A coupling structure for coupling an annular tool to a drive rod of another processing machine having a working spindle that can be rotated around a honing machine or spindle axis and can be moved back and forth parallel to the spindle axis (Not shown) at the spindle end of the annular tool (at the top of FIG. 2A).

  The annular cutting group 220 has a plurality (three in this example) of cutting material bodies 220-1, 220-2, and 220-3, and these cutting material bodies are uniformly distributed around the tool body. These cutting material bodies can be distributed and fed radially outwardly with respect to the tool axis 212 by means of a cutting material body feeding system, the purpose of which is the abrasively acting outer side of the cutting material body Is pressed against the inner surface of the bore to be machined with a defined contact pressure or pressing force, such an annular cutting group 220 is located at the end far from the spindle of the tool body (the bottom of FIG. 2A). ). Each of the three arcuately curved cutting material bodies is designed as a honing finish segment that is extremely wide in the circumferential direction but narrow in the axial direction and spans the angular range of 115 ° to 120 °. The honing finish segment is decoupled from the tool body and is radially displaceable relative to the tool body with respect to the tool axis 212. The ring formed by the honing finish segment terminates at the far side as seen from the spindle that is flush with the tool body so that the ring is at the far end as seen from the spindle of the annular tool. It is completely fitted in the half located far from the spindle of the main body.

  The axial length LHS of the honing finish segment is less than 15%, in particular less than 10% of the bore length L. The height of the honing finish segment is about 4 mm to 35 mm, in particular about 10 mm (axial direction), which in this example is 5% to 30%, in particular 10% of the effective outer diameter of the cutting part. It corresponds to ~ 20%. In this case, the axial length LHS corresponds to the axial length of the entire cutting area of the honing finish tool.

  Each body of cutting material is attached by soldering to the outer side of the associated steel support strips 224-1, 224-2. As a variant, the cutting material body may also be attached by gluing or screws, so that an easy exchange is possible. The inner side of each support strip interacts with the conical outer surface of the axially displaceable feed cone 232 such that the feed cone is driven by the machine-side feed device of the restoring springs 234, 226, 228. Having a beveled surface, which when the support strip is pushed in the direction of the far end as viewed from the spindle of the annular tool facing away from the forces of 234, 226, 228 Is fed radially inward together with the cutting material body supported by. For the reverse feed movement, the support strip is returned radially inward with the honing finish segment by peripheral return springs 226,228. As a result, the radial position of the cutting material body is controlled without play by the axial position of the feed cone 232.

  The technical concept for this tool is particularly suitable for machining cylinder bores with reduced honing finish overrun, for example with a honing finish reduced run of at most 5 mm. This type of geometry typically occurs in a blind hole bore or in a monoblock engine or a V-shaped engine.

  FIG. 3 shows an annular tool 300 as an exemplary embodiment, which is similarly a single tool located at the end of the tool body 310 far away from the spindle. An annular cutting group 320 is provided. FIG. 3A is a longitudinal sectional view of the annular tool, and FIG. 3B is a transverse sectional view of the cutting group. However, in contrast to the exemplary embodiment of FIG. 2, a honing tool is provided in which double expansion is performed. The annular cutting group 320 has two groups of honing finishing segments that can be fed separately and independently, and the honing finishing segments belonging to these groups are arranged alternately with respect to each other in the circumferential direction. ing. The first group of honing segments has three first honing segments 320-1, which are arranged circumferentially offset from each other by 120 °. Three second honing finishing segments 320-2 belonging to the second group of honing finishing segments are each arranged between these first honing finishing segments. The first group has a cutting material body with relatively rough cutting layers, and the second group has a cutting material body with relatively fine cutting layers relative to these rough cutting layers. Axial guide strips 326 are each disposed between adjacent honing segments. A spherical joint 350 is provided between the tool body 310 and the coupling structure 340, which coupling structure is provided for coupling the honing finish tool to a work spindle or the like, so that the honing finish tool is attached to the honing spindle. On the other hand, it can move to a limited extent in a plurality of axes.

  The first honing finish segment can be fed radially by the first feeding system. The first infeed system includes a first infeed rod 332-I that extends over the center of the tool body and has a conical cross section at the end far from the spindle. And this conical cross section interacts with the beveled surface of the first group of support strips of the honing segment. A second infeed system serves to deliver a second group of honing finish segments, the second infeed system having a tubular infeed element 332-A, which in turn includes an infeed rod 332 -I surrounds and at its end far from the spindle has a conical outer surface that interacts with the oblique surface of the support strip of the second honing finish segment .

  Three honing segments belonging to the first group of honing segments can be expanded by the first infeed system, the purpose of which is a certain honing operation, for example a smoothing honing operation or a structure honing. It is to carry out finishing work. Alternatively, when feeding another group of honing finish segments having different types of cutting layers, different honing finishing operations, such as deburring honing finishing operations or plateau honing finishing operations can be performed. With the double-expanded annular tool, two different honing finishing operations can be carried out in succession, in which case no tool changes are made or another honing spindle for machining is used. I can't.

  4A, a partial view of FIG. 4, is a longitudinal cross-sectional view of an annular tool 400 as one embodiment of a double expansion scheme, which is in contrast to the exemplary embodiment of FIG. There are two annular cutting groups 420-1, 420-2, which are attached in an axially offset manner relative to each other within a portion of the tool body 410 that is remote from the spindle. Each of the annular cutting groups (cross section in FIG. 4B) has three common feedable honing finish segments, each spanning about 110 ° to 115 ° around the circumference. In contrast, the axial length of the honing finish segment is small, typically less than 10% of the bore length and / or outside the effective honing tool in the vicinity of the cutting material body. 10% to 20% of the diameter. Measuring nozzles 440 of the pneumatic diameter measuring system are each attached to the tool body between adjacent honing finish segments. The cutting groups are arranged in axial proximity to one another so that the cutting area of the honing tool in which the two annular cutting groups are arranged is substantially more axial in the axial direction than the effective outer diameter of the honing tool. Short.

  In some embodiments, the cutting material body is provided in a manner that allows it to flex elastically with respect to the tool body. As a result, the possibility of following the contour during the axial movement can be improved as an option. For example, a spring element (eg, a leaf spring, a compression coil spring, etc.) may be connected between the carrier element and the cutting material body. It is also possible to design the carrier element so that it can flex elastically by weakening the cross-section of the carrier material, for example in the form of a slot provided structurally at a suitable location.

  There are various configurations that can make a saddle bore with the desired surface structure of the bore inner surface by using one or more annular tools of the type described herein. A first exemplary embodiment will be described in connection with FIGS.

In the case of this alternative method, first a conventional honing tool is used, starting with a bore that has been machined beforehand, for example by precision drilling, and having a relatively long and narrow (thin) honing wheel in the axial direction. To make a honed bore with a cylindrical shape. In this case, the axial grinding wheel length I was about 1/2 to 2/3 of the entire bore length L. In the first honing finishing operation (preliminary honing finishing), this operation was performed using a diamond grindstone of type D107, and then an intermediate honing finishing operation was performed using a fine grain size (grain size D54). The result was a substantially cylindrical bore shape with a slight deviation from the ideal shape and a relatively smooth surface (R _z <8 μm). In this case, the honing overrun S on the inlet side and the outlet side was about 1/3 of the grindstone length in the same manner as in the conventional method. The honing overrun can be reduced during machining of the V or monoblock engine.

The following third honing finishing work was designed as a honing finishing work. By a honing finish operation, a saddle-shaped bore shape is created by performing removal that changes in the axial direction of the material using a geometrically indefinite cutting edge. In the third honing finishing operation (saddle honing finishing operation), this operation is similarly performed by a special stroke control which has a relatively long honing stone having a grinding wheel length I of 2/3 L and will be described with reference to FIG. did. FIG. 6 schematically shows the stroke position HP of the honing tool as a function of the honing time t during the hoisting work. After insertion of the honing tool, the cylinder face is initially machined from the first time t ₁ to the time t ₂ with exactly the same stroke length as the machining of the cylindrical bore at the first stroke position. move on. In this case, the term “stroke position” means a region between the upper reverse position UO and the lower reverse position UU of the reciprocating motion. Thus, each shift in the reverse location also changes the stroke position.

From the prescribed second time t ₂ , the honing machine automatically switches to small changes in the stroke position and, after each stroke, causes the upper reversal point UO to be chopped in the direction of the lower reversal point UU. . The temporary position of the second time t ₂ can be determined, for example, by a certain number of strokes, a predetermined honing time, a predetermined removal of material or another triggering parameter. Similarly, the degree of incremental IN of the change in the upper reversal point between two consecutive strokes can be adjusted as needed. After the stroke shift phase ends at the _third time t ₃ , the bore is honed at the new third stroke position reached, and finally the second bore section reaches the desired diameter and the saddle shape (see FIG. (See 1 for comparison).

  Depending on the minute changes in stroke shift and how the temporal order of stroke shift is predetermined, various radii and contact angles are created in the transition section. Therefore, these parameters can be determined in advance by stroke shift parameters. The honing finish operation is conveniently performed with a honing wheel, and the cutting material grains of these honing wheels are finer than the cutting material grains for pre-honing or intermediate honing. For example, this operation may be performed with diamond crystal grains in the range of D35, the purpose of which is to obtain a bowl shape that already has a relatively fine surface structure.

  While creating a ridge shape with a relatively long honing strip and small stroke shifts, a relatively rough surface structure having a small step similar to the sawtooth profile may be created in the transition region. This type of structure is generally undesirable. Therefore, to obtain the desired surface structure uniformly over the entire inner surface of the bore including the transition section and adjacent radius, the method described herein rounds the radius after the hoisting honing operation. And smoothing the surface with an annular tool. In this case, for example, this operation may be performed using a finer cutting means within the range of D10 to D15, particularly D12. Selection of a suitable annular tool (e.g. arranged in a single expansion, a double expansion with two cutting groups arranged in a common ring state, or two axially offset annular cutting groups) The double expansion with only two cutting groups) depends, inter alia, on the design of the cylinder block. The choice of tool may be tailored to the degree of honing overrun considered and / or the position and size of the lateral bore, for example. For example, if the cylinder crankcase has a large transverse bore, it is generally convenient to perform this task using a single expansion type annular tool (see, eg, FIG. 2). In an exemplary process, such an annular tool with an annular cutting group is used to smooth the grooves or burrs created in the transition section during the machining of the heel honing operation. With the annular tool, the radius of the transition region is also rounded, changing the surface values so that they are substantially identical to the surface values of the adjacent first and third bore sections.

  For this purpose, FIG. 7 is a measurement of the round profile of a saddle cylinder after use of a single expansion type annular tool in the illustrated process. The scale on the x-axis (parallel to the bore axis) in this figure is 5 mm per unit of measurement shown, and the scale on the y-axis (in the radial direction of the bore) is 10 μm.

The use of an annular tool not only provides advantages for the smooth edgeless contour shape of the bore contour in the axial direction. In the case of the annular tool of the type shown in the figure, the cutting material body of the annular cutting group occupies most of the periphery (for example, 70% to 80%) of the honing finish tool. A uniform overlap condition is created at every axial position during honing. The term “overlap” as used herein quantitatively means the uniformity of the distribution of honing finish grooves over the entire bore length and perimeter. When conventional honing tools with relatively long honing wheels are used, the bore may have non-uniform roughness or waviness or surface waviness under some ambient conditions. Depending on the design of the block, this problem can occur in serious situations, for example if the engine block has to be machined with a short honing tool exit. In the case of a honing finish tool exit that is only a few millimeters in length, non-uniform wear of the long honing wheel may occur, so the bore has a diameter that is obtained at the lower reversing point rather than the upper reversing point It may be small. Such problems need to be substantially avoided by selecting appropriate honing parameters when conventional honing tools (with long honing wheels) are used, but the configuration of the corresponding honing process is comparable. Time and cost. Often, multiple tests must be performed until the honing finish process configuration is optimized to avoid non-uniform machining with long wheels. Many conventional problems can be avoided when an annular tool is used. Among the advantages of an annular tool are, among others:
1. Since most of the periphery of the honing finish tool in the vicinity of the annular cutting group is occupied by the cutting material body, the inner surface of the bore can be structured much faster with the annular tool than with the grinding wheel tool. As a result, the cycle time can be shortened as an option.
2. For example, adjusting the stroke length to correct the shape will not cause the troublesome non-uniformity of the roughness distribution when an annular tool is used. This is because the overlap state is maintained even when the stroke length is changed.
3. When the annular cutting group wears substantially uniformly, and therefore an annular tool is used, undesirable conicities, especially near the lower reversal point, can be avoided.
4). The installation of a honing machine for a new honing finish process can proceed much easier and faster when an annular tool is used than when a conventional grinding wheel honing tool is used. The overlap state is sufficiently uniform within the requirements due to the tool configuration.

  Uniformity when using a single tool group ring for structuring and a double tool tool (for example, see FIG. 3) In order to guarantee an overlap condition, it will generally be necessary to increase the number of strokes compared to the use of a single expansion type annular tool. However, the advantage of the annular tool is maintained and the required number of strokes for the uniform structuring of the bore inner surface still varies with the stroke when using a conventional honing finish tool with a long honing wheel. Always less than the number of.

  When an annular tool is used, it is possible to conveniently exert the feed force by hydraulic expansion, and thus the surface can be substantially machined with a constant force. An axially changing contour continuation can only be produced by design due to the flexibility of hydraulic expansion.

  After smoothing the bore inner surface with an annular tool and rounding the radius, one or more further honing finish operations are then performed to finally give the desired surface structure to the saddle bore. Can be generated.

  As an example, the process just described is first performed, and then a fifth honing finish operation, referred to herein as “spiral structure honing with an annular tool”, is performed. In this honing operation, the axial speed and rotational speed of the honing tool are coordinated to produce a relatively large honing angle, for example on the order of 140 °. Of course, in other alternative methods, other honing angles and / or roughness profiles may also be produced. In the example, the helical structure honing is configured to provide removal of virtually no material, but only grooves of appropriate depth and distribution are created on the surface. Is very smooth after the rounding operation due to the relatively coarse grain cutting material body having a low cutting grain density. For example, a cutting material body having a cutting material crystal grain density of 1.25 to 15% by volume and / or a crystal grain size of 35 to 200 μm can be used (for example, German Patent Application Publication No. 102005018277 (A1)). See the description for comparison).

  Next, in the sixth final honing operation, the previously structured surface is also deburred (deburring honing). For this purpose, it is also preferable to use an annular tool containing fine cutting material, for example the same annular tool which is also used for the fourth honing operation (R rounding and smooth honing). The work in this case is preferably performed in different extended formats. The expansion type may be configured as hydraulic / hydraulic, hydraulic / mechanical, or mechanical / mechanical. In the case of mechanical expansion, for example, the movement may be performed by a force control system by servo mechanical expansion (expansion such as hydraulic pressure) or by a piston and force control system.

  In another form of the method, an expandable annular tool is used in the saddle honing operation, i.e., when creating a saddle bore shape from the previous still cylindrical bore shape. For this purpose, the control of the expansion system for the radial feeding of the honing finish segment is coupled to a control device for the stroke position so that the annular tool can produce a transitional section with a gradual diameter and the cylinder It is adapted to operate at a suitable constant pressure within the first and second bore sections of the shape (see FIG. 8 for comparison). The dredge honing operation may be provided as a second honing operation immediately after the preliminary honing finish, and in this regard, the dredge honing operation is the second to fourth honing of the first exemplary embodiment. Can replace the finishing work. In this case, the stroke-dependent control of the expansion moves the honing finish segment of the cutting group according to the stroke position according to the heel according to the downward stroke and moves it in the radial direction by the movement and force control method or moves upward according to the heel shape according to the stroke position During the stroke it happens to retract again in the radial direction near the transition section. Thus, a smooth contour shape can be achieved in the transition segment from the beginning.

  This is because a specific stroke range corresponding to the first to third bore sections is input to the control program, and therefore the end of the first bore section is being cut while the cutting group is moving downward and stroke due to force control expansion. Can be achieved at the honing machine. Next, during the upward stroke, the expansion of the cutting group retracts from the end of the third bore section, resulting in the desired programmed saddle-shaped cylinder. For this purpose, FIG. 8 shows, as an example, the dependence of the axial stroke position HP (solid line) and the radial extension position AP (dashed line) as a function of the honing finish time t during the hoisting with an annular tool. FIG.

  Not only can an annular tool of the type described herein be used to create or machine a saddle bore, but it is also prominent without modification during machining of bores having different geometric shapes. Can provide benefits. For example, in order to create a free shape with a non-circular bore cross-section made in the bore, a double expansion scheme is employed in the same or substantially the same manner as the exemplary embodiment of FIG. It is possible to use an annular tool with This is customarily called “shape honing”. For example, a bore section with a clover-shaped or elliptical cross-section can be made with an annular tool. For this purpose, the honing machine must be able to control the first feeding system and the second feeding system simultaneously, depending on the stroke position and the angular position of the cutting group relative to the bore in each case. Expansion must be controlled at different forces / positions so that can occur.

  It is also possible to use an annular tool to create and / or machine a bore shape having a frustoconical bore section (conical section), this truncated cone bore section being a separate bore section. Merge into adjacent cylindrical bore sections relatively abruptly or without transition rounding. As a result, for example, a funnel-shaped bore can be made, which has a cylindrical first bore section on the input side of a first diameter, the first diameter being Increases in a conical shape toward the bore base up to a maximum diameter within the two bore sections. The maximum diameter difference between the cylindrical first bore section and the conical second bore section may be, for example, about 20 μm to about 90 μm. The axial length of the cylindrical first bore section may be, for example, 20% to 80% of the entire bore length.

  In addition, the annular tool makes it possible to create a barrel-shaped bore section in the bore, i.e. a bulge in an otherwise substantially cylindrical bore. The bulge can be located approximately in the middle or near one of the bore ends.

  Also, when an annular tool is used, a narrow strip having a surface structure different from that in the central region of the highest piston speed is provided near the top dead center and / or near the bottom dead center. It is relatively cost effective to machine the cylinder face. This form is referred to herein as “strip honing”. A conventional method suitable for this purpose and a honing tool constructed correspondingly are described, for example, in DE 195 54 922 (C2). In addition to honing machining in which the entire axial length of the honing tool is machined by a long honing wheel, short stroke honing machining is here performed by a short honing wheel, which is Covers only near dead center and / or bottom dead center.

  If a double tool is used and an annular tool with two axially offset cutting groups is used (see for example FIG. 4), corresponding surface machining is possible as well. For example, the first annular cutting group may perform long stroke machining of the entire bore length, and then, for example, the second cutting group may perform short stroke machining near top dead center. Create a specific structure near top dead center.

  Further, when variable control corresponding to the ratio between the number of stroke cycles and the number of rotation cycles of the work spindle is performed, such an effect is obtained that such strip honing can be performed with different honing angles in different axial bore sections. This can be achieved in a simple manner (for example, see FIG. 4 of DE 102007032370 (A1)).

Claims (16)

A honing finishing method in which an inner surface of a bore of a workpiece is machined by at least one honing finishing operation, and in the honing finishing operation, an expandable honing finishing tool is moved up and down in the bore to move in the axial direction of the bore. Producing a bore shape that deviates from a cylindrical shape by causing the reciprocating motion at the same time to rotate the extended honing finishing tool to produce a rotational motion combined with the reciprocating motion.
Creating a bowl-shaped bore, the bore following the bore inlet, having a first bore section with a first diameter, a second diameter greater than the first diameter and away from the bore inlet; A second bore section located, and a transition section continuously transitioning from the first diameter to the second diameter and located between the first bore section and the second bore section. Designed as a honing finish segment that is distributed around the circumference of the tool body and is wide in the circumferential direction and narrow in the axial direction during at least one honing finish operation. The honing measured axially using an annular tool (200, 300, 400) having at least one annular cutting group (220, 320, 420) comprising a plurality of radially feedable cutting material bodies. The axial length of the raised segment is smaller than the width measured in the circumferential direction, and the axial length of the cutting group provided with the cutting material body is smaller than the effective outer diameter of the honing finishing tool. Method.   The honing finishing method according to claim 1, wherein first, a bore having a cylindrical bore shape is formed, and then, in the hoisting honing operation, the hoisting boring shape is made by honing finishing by removing honing finishing changing in the axial direction. .   During the hoisting honing operation, using an extended honing finishing tool having at least one annular cutting group, the honing finishing segment of the cutting group is fed in a radial direction during a downward stroke according to the hoisting shape according to the stroke position; And the honing finishing method of Claim 2 which retracts in a radial direction during an upward stroke according to the said scissors shape according to the said stroke position.   In the first honing operation, an expanded honing tool having a honing wheel having a length exceeding 50% of the length of the bore is used. In the first stage, the honing tool is moved to the first stroke position. Move up and down between the upper and lower reversing locations, and then in a second stage, gradually change the upper reversing location in the direction of the lower reversing location and thus the stroke position 3. Honing according to claim 2, wherein the honing is shifted in the direction of the second stroke position in the vicinity of the second bore section and then the honing finishing tool is moved up and down at the second stroke position in a third stage. Finishing method. After the scissor honing finishing operation, a smoothing honing finishing operation is performed to smooth the bore contour of the transition section. Ru used, honed method of claim 4.   After the hoisting honing operation, a smoothing honing finishing operation for smoothing the bore contour of the transition section is performed, and during the smoothing honing finishing operation, the cutting material body is fixed to the inner surface of the bore with a constant feeding force. The honing finishing method according to claim 4, wherein the honing finish method is pressed against the honing. A tool body (210, 310, 410) defining a tool axis, at least one cutting group (220, 320, 420) attached to said tool body and having a cutting material body for material removal machining of the inner surface of the bore; And a honing finishing tool having a cutting group feeding system assigned to the cutting group and exerting a feeding force and acting on the cutting material body of the cutting group in a radial direction with respect to the tool axis,
The honing finishing tool (200, 300, 400) is designed as an annular tool, the honing finishing tool being distributed around the circumference of the tool body and having a wide and circumferential axis. At least one annular cutting group comprising three or more radially feedable cutting material bodies (220-1, 220-2, 220-3) designed as a narrow honing finish segment in the direction (220, 320, 420) The axial length (LHS) of the honing finish segment measured in the axial direction is smaller than the width measured in the circumferential direction, and the cutting group including the cutting material body The honing finish tool has an axial length smaller than the effective outer diameter of the honing finish tool. The axial length of the honing finish segment is less than 30% of the effective outer diameter of the honing finishing tool and / or the axial length of the honing finish segment is in the range of 5 mm to 20 mm and / or Alternatively, the honing finish tool of claim 7 , wherein the axial length of the honing finish segment is less than 10% of the bore length of the bore to be honed. The honing finishing tool according to claim 7 or 8 , wherein more than half of the circumference of the annular cutting group (220, 320, 420) is occupied by a cutting material body. The honing finish tool according to any one of claims 7 to 9 , wherein the cutting group includes three, four, five, or six honing finish segments. The cutting group (220, 320, 420) is exclusively arranged near the end far from the spindle of the tool body so that the cutting group is located in a half that is far from the spindle of the tool body. has been that, honed tool according to any one of claims 7-10. Said annular tool (200, 300), said tool having a body single annular cutting group arranged at the free end of (210, 310) (220, 320), any of the claims 7-11 Honing finishing tool as described in Kaichi. The annular cutting group (320) has two groups (320-1, 320-2) of honing finishing segments that can be fed separately and independently, and the honing finishing segments of the group alternate in the circumferential direction. The honing finish tool according to any one of claims 7 to 12 , which is arranged in a manner located on the surface. The annular tool (400) is disposed in an axially offset state with respect to the first annular cutting group (420-1) and the first annular cutting group, and is separate from the first annular cutting group. to have a separate at least one second annular cutting group capable infeed (420-2), honed tool according to any one of claims 7-11. One or more sensors of diameter measurement systems is provided in the honing tool, honing tool according to any one of claims 7 to 14. The honing finishing tool according to any one of claims 7 to 15 , wherein an integral multi-axis movable joint is provided in the tool body.

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