JP5633208B2 - Honing method - Google Patents

Description

The present invention relates to a honing method and honing apparatus for flat machining an inner surface of a cylinder of the engine, about the honing how the cycle time to stabilize.

  The inner surface of the cylinder of the engine is a sliding surface that slides in contact with the piston ring, and is required to be processed flat. However, even if it is processed flat, it is not processed into a complete mirror surface. If the inner surface of the cylinder becomes a mirror surface, the piston ring will be burned out. On the inner surface of the cylinder, minute grooves are formed at appropriate intervals so as to collect lubricating oil.

  A honing device performs such machining of the cylinder inner surface with a grindstone. The honing device polishes the cylinder inner surface by rotating while pushing the grindstone held so as to be in contact with the cylinder inner surface toward the cylinder inner surface. Hereinafter, the operation of pushing the grindstone toward the inner surface of the cylinder is referred to as expansion according to the custom.

  In order to process the cylinder inner surface flatly and form a groove, a plurality of types of grindstones having different roughnesses are replaced and used. As shown in FIG. 6, a groove M having a wide opening and a deep depth is formed on the inner surface of the cylinder polished with a grindstone having a large roughness. When the inner surface of the cylinder is polished with a grindstone having a fine roughness, as shown in FIG. 7, the crest portion of the groove M is polished, and the inner surface of the cylinder having grooves is formed with an appropriate feeling while being entirely flat. Is done.

  By the way, as the grindstone is used, the polishing power decreases and the sharpness decreases. After grinding with a grindstone with a large roughness, when grinding with a grindstone with a fine roughness and forcibly expanding the grindstone with a strong force and processing it, plastic flow occurs on the inner surface of the cylinder, and it is rubbed. It crushes and the groove is closed.

  However, the grindstone has a self-generating action. A grindstone has a structure in which minute abrasive grains that are hard, sharp, and formed in a substantially constant size are embedded in a soft and easy-to-peel bond material. The sharpness of the grindstone is lowered because the abrasive grains exposed on the surface are rounded. When the abrasive grains are rounded, the resistance against the cylinder inner surface increases, the bond material peels off with the abrasive grains, and the fresh abrasive grains in the inner layer are exposed, so the sharpness is restored. This is called spontaneous action.

  As described above, the plastic flow tends to occur when the sharpness of the grindstone is lowered. However, if the polishing is continued as it is, the sharpness is restored by the self-generated action, and the plastic flow does not occur. In order to reduce the plastic flow, it is preferable to use a grindstone using a softer bond material, but on the other hand, the wear of the grindstone is promoted and the life of the grindstone is shortened. On the contrary, there is a dilemma that it becomes difficult to prevent plastic flow when using a grindstone with a hard bond material and a long life.

JP-A-9-300203

  There are a hydraulic type and a mechanical type (ball screw type) as an expansion mechanism for expanding the grindstone.

  A conventional hydraulic expansion mechanism expands a grindstone with a constant hydraulic pressure over time. Since the grindstone is always expanded with a constant force, plastic flow can be suppressed by setting an oil pressure at which plastic flow hardly occurs. However, since the grindstone is always expanded with a constant force, when the abrasive grains are rounded and the sharpness of the grindstone deteriorates, the time required to expand the same expansion amount (processed inner diameter distance) is good when the grindstone is sharp Longer than As a result, the time (cycle time) required to process one cylinder is not stable. In addition, when the sharpness of the grindstone is good, the required time is short, but the roughness of the finished surface becomes large and the processing quality is not good. When the sharpness of the grindstone is lowered, the roughness of the finished surface is reduced and the processing quality is improved.

  The mechanical expansion mechanism expands the grindstone at a constant speed using a powerful motor. Whether the grindstone is sharp or bad, the time required to expand the same expansion amount is constant, and the cycle time is also constant. However, since the grindstone is forcibly expanded, plastic flow tends to occur. Since the groove is blocked by plastic flow, the processing quality is not good.

An object of the present invention is to solve the above problems, the quality of machining is stabilized, the cycle time is to provide a honing how to stabilize.

In order to achieve the above object, the honing method of the present invention includes a grindstone used for finishing the inner surface of a cylinder, a rotating mechanism that rotates the grindstone in a radially expandable manner, and the grindstone having a diameter by hydraulic pressure. an expansion mechanism for expanding direction, and a sizing mechanism to measure the required time required to process a given distance in the cylinder radial direction, the inner surface of the cylinder by the hydraulic force to rotate in contact with the grinding wheel to the inner surface of the cylinder In the honing method in which the grindstone is self-generated by expanding toward the finish, the inner surface of the cylinder is finished, and a signal is issued every time a predetermined step set in advance by the sizing mechanism is reached, and the time interval of the signal is constant in the cylinder radial direction. measured as increments distance ([Delta] d) required time taken to process a (t), the required time (t) is, when shorter than the target time (t0) is Reducing the pressure, long and sometimes increases the oil pressure in the cycle time for processing the one cylinder, the hydraulic force and the measuring the relative duration (t) for each of the predetermined increments distance ([Delta] d) Decreasing or increasing is repeated .

  The present invention exhibits the following excellent effects.

  (1) The quality of processing is stabilized.

  (2) The cycle time is stabilized.

It is a block diagram of the honing apparatus which shows one Embodiment of this invention. It is a horizontal sectional view of the grindstone part of the honing apparatus of FIG. It is a figure explaining the control procedure of this invention. It is a graph which shows transition of processing distance within cycle time. It is a graph of the required time with respect to a processing distance. It is an image figure of the cylinder inner surface grind | polished with the grindstone with large roughness. It is an image figure of the cylinder inner surface grind | polished with the grindstone with fine roughness after grind | polishing with a grindstone with large roughness.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a honing device 1 according to the present invention includes a grindstone 2 used for finishing a cylinder inner surface S, a rotating mechanism 3 that rotates while holding the grindstone 2 so as to be expandable in a radial direction, and a grindstone. The expansion mechanism 4 that expands 2 in the radial direction with oil pressure, the sizing mechanism 5 that measures the time required to process a predetermined distance in the cylinder radial direction, and the oil pressure when the required time is shorter than the target time The required time stabilizing means 6 is provided for reducing the oil pressure when the required time is longer than the target time.

  The grindstone 2 has a structure in which abrasive grains are embedded in a bond material, and has a self-generating action. The grindstone 2 is fixed to a vertical surface of a base plate 11 having a vertical surface at one end and a slope at the opposite end. As shown in FIG. 2, the base plate 11 is erected on the cylinder diameter so as to be orthogonal to the cylinder inner surface S that is a workpiece, and is held by the rotating mechanism 3 with the grindstone 2 facing the cylinder inner surface S.

  The rotating mechanism 3 includes a vertical rotating cylinder 14 that is rotated by a motor 12 via a pulley belt 13, and a honing head 15 provided at the lower end of the vertical rotating cylinder 14. As shown in FIG. 2, the honing head 15 has a plurality of slots 16 in the circumferential direction for holding the base plate 11 movably in the radial direction, and the base plate 11 can be held in each slot 16. With this structure, the rotation mechanism 3 can hold the grindstone 2 in an expandable manner.

  The expansion mechanism 4 includes a push-down mechanism 17 composed of a hydraulic cylinder or a hydraulic servo motor, a rod 18 connected to the push-down mechanism 17 and inserted through the vertical rotating cylinder 14 of the rotation mechanism 3, and a draw bar provided at the lower end of the rod 18. 19. The draw bar 19 is formed in a conical shape such that the warp becomes narrower toward the lower end, and the inclined surface of the base plate 11 is in contact with the conical surface.

  In FIG. 2, a horizontal cross section of the contact surface between the draw bar 19 and the base plate 11 at a position different in height from the cross section is indicated by an imaginary line (dashed line). When the draw bar 19 is pushed down, the diameter of the imaginary line increases, the base plate 11 is pushed, and the grindstone 2 is expanded. Therefore, as shown in FIG. 1, when the draw bar 19 is continuously pressed down by the pressing mechanism 17, the grindstone 2 is expanded continuously in time. The expansion force of the grindstone 2 is proportional to the pressing force of the pressing mechanism 17, that is, the oil pressure.

  The sizing mechanism 5 is a conventionally known air micrometer 20 that measures the gap between the outer surface of the honing head 15 and the cylinder inner surface S, and every time the reading value of the air micrometer 20 reaches a preset constant increment. A time measuring device 21 for outputting a signal and measuring a time interval of the signal as a required time required to process a predetermined distance in the cylinder radial direction;

  The honing device 1 may be provided with an elevating mechanism (not shown) that raises and lowers the entire rotating mechanism 3 and the expansion mechanism 4 in order to move the honing head 15 in the longitudinal direction of the cylinder.

  The required time stabilization means 6 is realized by executing a procedure written in advance in the sequencer.

  As shown in FIG. 3, the control procedure of the present invention is such that the distance in the cylinder radial direction, which is the gap between the outer surface of the honing head 15 and the cylinder inner surface S, is d1, d2, d3,. When the distance is increased, time measurement is started at the distance d1, and time measurement is ended at the distance d2, and a required time t required to process the step distance Δd is obtained. Reflecting this required time t, an expansion pressure between the distance d2 and the distance d3 is set. The required time from the distance d2 to the distance d3 is reflected in the next expansion pressure. This procedure is repeated.

  Hereinafter, operation | movement of the honing apparatus 1 of this invention is demonstrated.

  Finishing of the cylinder inner surface S is performed by polishing the cylinder inner surface S by rotating the grindstone 2 in contact with the cylinder inner surface S by the rotation mechanism 3. At this time, although the sharpness of the grindstone 2 decreases with time, the processing is continued while the grindstone 2 grows spontaneously by expanding the grindstone 2 toward the cylinder inner surface S by the expansion mechanism 4.

  As shown in FIG. 4, in the honing device using the conventional hydraulic expansion mechanism, the grindstone is expanded with a constant hydraulic pressure in time, so when the sharpness of the grindstone is lowered, from the distance d1 to the distance d2. The required time t1 is required to process the step distance Δd. When the sharpness of the grindstone is restored by the self-generated action, the time t2 is required to process the step distance Δd from the distance d4 to the distance d5. As the sharpness of the grindstone repeatedly fluctuates, the time required to process the step distance Δd is unstable, and as a result, the cycle time for processing one cylinder becomes unstable.

  As shown in FIG. 5, when the required time for each step distance Δd in FIG. 4 is shown in the same origin graph, the required time t1 is longer than the required time t2.

  In the present invention, the target time t0 is set, and when the measured required time is longer than the target time t0, such as t1, the expansion pressure is increased. When the expansion pressure increases, the self-generating action of the grindstone 2 is promoted and the required time is shortened.

  When the measured required time is shorter than the target time t0, such as t2, the expansion pressure is lowered. When the expansion pressure is lowered, the required time is lengthened, but the plastic flow is reduced, the roughness of the finished surface is reduced, and the processing quality is improved.

  By repeating such control, the required time for each step distance Δd converges to the target time t0. As a result, the processing quality at each step distance Δd is made uniform and stable. In addition, since the required time for each step distance Δd is stabilized at the target time t0, the cycle time for machining one cylinder is stabilized, and the daily production volume can be easily managed. Thus, quality and production volume are optimized respectively.

DESCRIPTION OF SYMBOLS 1 Honing apparatus 2 Whetstone 3 Rotating mechanism 4 Expansion mechanism 5 Sizing mechanism 6 Time required stabilization means

Claims (1)

A grindstone used for finishing the inner surface of the cylinder;
A rotating mechanism for rotating the grindstone in a radially expandable manner; and
An expansion mechanism for expanding the grindstone in the radial direction with hydraulic pressure;
A sizing mechanism that measures the time required to process a predetermined distance in the cylinder radial direction,
In the honing method in which the grindstone is rotated while being in contact with the cylinder inner surface and expanded toward the cylinder inner surface with hydraulic pressure, the grindstone is self-generated and the honing method finishes the cylinder inner surface.
A signal is output every time a predetermined step set by the sizing mechanism is reached, and the time interval of the signal is measured as the required time (t) required to process a fixed step distance (Δd) in the cylinder radial direction. ,
The required time (t) is, when shorter than the target time (t0) reduces the oil pressure increases the longer Sometimes oil pressure,
During the cycle time for machining one cylinder, the measurement and the decrease or increase of the hydraulic pressure are repeatedly performed for the required time (t) for each constant step distance (Δd). Honing method.

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