JPS62287965A - Machining method for engine cylinder - Google Patents

Abstract

PURPOSE:To ensure the circularity of cylinder bore at all times by fitting a dummy head to a cylinder head, inserting a heating head in the bore for heating a cylinder part and machining the heated cylinder part. CONSTITUTION:A cylinder block 1 is so constituted that a dummy head 2 analogous to a cylinder head is fixed with a tightening bolt, transferred to a heating station via a transfer table 14, a heating head 13 comprising a heating coil 12 wound about the support member 11 thereof is inserted in each bore with a heating device 10 utilizing an induction hardening device and an internal bore wall is heated approximately up to the same temperature as in engine operation. And rough machining, intermediate finishing and horning are carried out under a tightening force and a temperature condition near the case of an actual engine. According to the aforesaid process, both of mechanical deformation due to the tightening of a cylinder head and thermal deformation at the time of engine operation can be properly absorbed and the circularity of a cylinder bore can always be ensured without any complicated machining process.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for machining cylinders, particularly cylinder bores, that constitute an engine body.

[Prior art] Engine cylinder blocks are usually cast products.
After casting, it is necessary to perform precision machining of the cylinder bore.

Generally, cylinder bore machining is performed on a single cylinder block at room temperature, and after machining, various engine parts are assembled and the cylinder head is bolted to the cylinder block before being supplied as an actual machine.

In that case, no matter how well roundness is ensured during cylinder bore machining, deformation due to the tightening force when bolting the cylinder head and thermal deformation caused by temperature rise during engine operation cannot be avoided. For this reason, in conventional cylinder bore machining, these deformation factors have been predicted in advance and bore machining has been carried out, but the current situation is that it is not possible to effectively absorb the deformation that actually occurs based on theoretical considerations alone.

In consideration of the deformation of the cylinder head due to bolt tightening, Japanese Patent Publication No. 51-25523 proposes a processing method in which a cylinder block is bored while a dummy head is bolted to the cylinder block.

In this cylinder block processing method, the bore is machined while the cylinder head is deformed due to tightening, so the bore deformation caused by the cylinder head tightening can certainly be absorbed, but thermal deformation during carrot operation is avoided. It is not possible.

Such thermal deformation is non-uniform because the temperature distribution around the Norinda pore is non-uniform, and non-uniform thermal deformation is
Resulting in increased oil consumption and blow-by gas.

[Object of the Invention] The object of the present invention is to provide an engine-use product that can reliably absorb both the deformation caused by the tightening of the cylinder head and the thermal deformation during engine operation, and which can always ensure the roundness of the cylinder pore. An object of the present invention is to provide a method for machining a cylinder.

[Structure of the Invention] For this reason, the present invention provides a method for attaching a dummy head similar to a cylinder head to a cylinder block by tightening bolts.
Next, a heating head is inserted into the cylinder bore to heat each bore portion of the norinda to the temperature state during engine operation, and then the bore is machined.

[Effects of the Invention] According to the present invention, since the bore is machined with the head bolted and further thermally deformed, the bore can be machined with high precision, and there is no need to perform complicated machining. Since the roundness can be ensured in this state, the machining work itself can be made easier, and by optimizing the bore shape, oil consumption and blow-by gas can be reduced. .

[Embodiments] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

As schematically shown in FIG. 2, a rectangular plate-shaped dummy head 2 is prepared in advance in correspondence with a cylinder head (not shown) to be attached to the upper surface of a cylinder block l to be bored.

This dummy head 2 has #l~ of the cylinder block 1.
#4 bore and each bolt hole 3.3. Holes 4, 4, which correspond to ..., respectively. ...and Porto hole 5,5. ... is drilled. Then, after overlapping the dummy head 2 on the top surface of the cylinder block l, the
Tighten and secure with a tightening bolt.

Figures 3 (a) and (b) show the #l bore when the cylinder head is actually tightened to the cylinder block l.

The tightening deformation of #2 bore is shown with the amount of deformation enlarged. In addition, in Fig. 3 (a) and (b), F and R indicate the front and rear of the engine, and thrust and anti-thrust are as follows.
The side on which the piston receives thrust force and the side on which it does not are shown, respectively; the dotted line represents the measured value at a position 15xz from the top, and the dashed line represents the measured value at a position 3H from the top.

The shape of the contact surface, rigidity, tightening force, etc. of the dummy head 2 are taken into consideration so that the amount of tightening deformation is substantially the same as when tightening a real cylinder head.

After attaching the dummy head 2 to the cylinder block l as described above, as shown in FIG. heat up.

In this heating device 10, a heating head 13, in which a heating coil 12 is wound and supported on a cylindrical support 11 integrally provided with an inverted conical tip guide, is supported in each bore of a cylinder block l so as to be freely insertable and removable. The heating coil 12
In this case, a high frequency current is supplied by a motor generator (not specifically shown) provided in the heating device 1O, and the circumferential wall of each bore of the cylinder block 1 is heated in a short time by the principle of induction heating.

As shown in FIG. 4, the cylinder block l with the dummy head 2 attached thereto is conveyed on a conveyor roller table 14, and passed to the heating device 10 installed in the heating station, where the heating head 13 is placed in the bore. The bore wall is heated using the induction heating method described above.

Although only one heating head 13 is shown in FIG. 4, if the engine has four cylinders, four heating heads 13 are arranged in parallel so that the four bores can be heated all at once.

For reference, Figure 5 shows the temperature distribution of #3 bore during engine operation.

This temperature distribution is at 6,000 rpm (at full throttle)
This is obtained when the top ring is at the top dead center position when operating at a cooling water temperature of 80°C, and what is characteristic is that the front is sandwiched between other cylinders.

The temperature becomes high on the rear side, resulting in an elliptical distribution with long sleeves in the front and rear directions.

Note that if cooling water passages are provided between the cylinders, the temperatures on the front and rear sides will drop considerably, as shown by the dotted lines in FIG.

The wall temperature of the cylinder bore is not uniform as described above, and also differs in the vertical direction.

In order to achieve such a wall temperature, the heating conditions are actually adjusted in advance by various methods, such as changing the coil density of the heating head and changing the vertical movement speed. Further, in order to prevent a temperature drop during bore machining after heating, it is preferable to supply a heat medium such as heated oil or hot water to a water jacket (not shown) in the cylinder block l.

After each cylinder bore is heated as described above, the bore is machined. Since the temperature of the machined surface is high during this bore machining, the high-temperature grinding conditions for the abrasive grains of the grindstone, binder, etc. are examined, and solid lubricants are added if necessary. Furthermore, for the grinding fluid, an extreme pressure additive or the like is added to a mixture of white kerosene and sombre oil, and the viscosity is also adjusted using an extreme pressure viscosity oil or the like.

Note that it may be determined as necessary whether the bore surface processing after heating should include rough processing and semi-finishing, or only honing finishing processing.

FIG. 1 is a process diagram showing a method of rolling and cylinder processing according to an embodiment of the present invention.

That is, after uncasting the cast cylinder block,
First, machining other than the bore, such as the reference surface, the top surface of the block, etc.
Grind the bottom surface, side surfaces, etc., and machine the head bolt mounting holes (Step I).

Next, in step (2), a dummy head is attached.

As mentioned above, when tightening this dummy head, the tightening force is adjusted so that the state is the same as when the cylinder is actually tightened. Then, using a high-frequency induction heating method, the bore section is heated to a temperature close to that of the operating engine (step ①).

In addition to the above-mentioned high-frequency heating, heating oil or water is supplied to the water jacket part of the cylinder block in order to prevent temperature drop during bore machining and to bring the temperature distribution of the bore closer to that of the actual engine (Step ■) .

After that, first, as rough machining of the cylinder bore, 06
Grinding is performed to approximately 0.8 mm (Step ①).

Next, the process of semi-finishing the bore of about 0.3 to 0.4■), and finally honing to 0.01571m.
Apply some finishing processing (Step ■).

Note that the processing order may be such that the block processing is followed by the bore rough processing (step ①), and then the dummy head is attached and the subsequent processing is performed.

In that case, after heating, intermediate finishing of the bore and finishing by honing the bore are performed while maintaining the temperature state.

Various other processing orders can be considered, for example, a process order such as 1-n-■-rv-v-m-vr-■-■ may be adopted.

The point is, considering both cost and processing accuracy,
A preferred process order may be adopted.

[Brief explanation of drawings]

FIG. 1 is a process explanatory diagram according to an embodiment of the present invention, FIG. 2 is a perspective view showing a cylinder block and a dummy head, and FIG.
Figures (a) and (b) are plan explanatory views showing deformation of the cylinder bore when the cylinder head is tightened, Figure 4 is a side view showing an example of the heating device, and Figure 5 is #3 during engine operation.
FIG. 3 is an explanatory plan view showing the temperature distribution of a cylinder. l...Cylinder block, 2...Dummy head, 10
... Heating device, 13... Heating head. Patent applicant: Mazda Motor Corporation Agent: Patent attorney: Aohaku Ao and two others 11EI Figures (a) (b) Figure 4, page 5 R (Lyairiri)

Claims (1)

[Claims] (1) A method of machining the cylinder part of an engine, comprising:
A method for machining an engine cylinder consisting of the following steps; a step of attaching a dummy head similar to an engine cylinder head to a cylinder block, a step of inserting a heating head into the bore of the cylinder block to heat the cylinder part, and heating. Process of machining the cylinder part.