The cylinder block journal boring machine is suitable for the repair of automobile engines, mainly used for boring the main journals and camshaft journals of the engine cylinder block. It can also be used for micro-boring the flywheel contour holes and journal seat holes. Through the processing of the cylinder block journal, its inner diameter size and roundness meet the technical requirements. This article will take the T8120×20VF cylinder block journal boring machine sold by Shaanxi Hao Yong Machinery Co., Ltd. as an example to introduce the use and maintenance of the cylinder block journal boring machine. The cylinder block journal boring machine is suitable for the repair of automobile engines, mainly used for boring the main journals and camshaft journals of the engine cylinder block. It can also be used for micro-boring the flywheel contour holes and journal seat holes. Through the processing of the cylinder block journal, its inner diameter size and roundness meet the technical requirements.

When boring the cylinder block journal, the cylinder block is installed on the machine bed's packing block for positioning, and the journal is aligned with the boring bar through the centering sleeve and centering gauge. Then, the boring bar is made coaxial with the machine spindle by raising and lowering the headstock. The boring of the journal is achieved by the rotation and axial feed of the boring bar. To achieve the above movement, the transmission system of the machine consists of the following four parts:

1. Boring bar rotational movement

The rotational movement of the boring bar is transmitted to the shaft sleeve through a pair of synchronous belt pulleys by a variable frequency motor (equipped with a stepless speed regulator). The shaft sleeve is connected to the spindle by a sliding key. The spindle is connected to the boring bar through a universal joint. Thus, the rotational movement of the boring bar is realized.

The spindle speed (60-476r/min) is obtained by the cooperation of the variable frequency motor (equipped with a stepless speed regulator and inverter) and the synchronous belt pulley. When it is necessary to change the spindle speed, first select the spindle speed according to the speed required for the workpiece processing, turn on the motor, and then rotate the speed adjusting knob on the speed regulator until the value displayed on the speed display installed on the control panel is consistent with the required speed. Note: The motor must be turned on before rotating the speed adjusting knob.

2. Boring bar feed movement

The feed movement of the boring bar is achieved by the main motor power and the headstock feed gear. The feed speed is controlled by the feed speed handle on the control panel (select the feed speed according to the cutting amount). The feed direction of the spindle is controlled by the forward and reverse control buttons of the motor. Forward rotation is the forward direction, and reverse rotation is the backward direction. Both direction control buttons are mechanically self-locking buttons. When infeed is required, press the motor forward direction control button, and the boring bar will perform the forward movement. When it is necessary to stop the infeed movement, simply press the stop control button again to reset it. The reverse direction is the same. (Note: The forward direction control button and the backward direction control button cannot be pressed at the same time!)

3. Headstock lifting and lowering movement

Loosen the clamping handle, and the headstock can be raised and lowered by hand-cranking the large column handle. The principle is that through the bevel gear pair and screw-nut pair, the nut is fixed on the inner column, and the inner column is fixed with the sleeve. When the screw rotates, the nut does not move, and the screw drives the headstock fixed to the column to rise and fall.

4. Boring tool adjustment movement

(1) Longitudinal horizontal movement of the boring tool along the bed guideway:

Loosen the clamping handle at the bottom of the left and right bases. When rotating the sprocket shaft head with a ratchet wrench, the boring tool is adjusted longitudinally along the bed guideway according to the cylinder block length through the sprocket and the chain fixed on the bed.

(2) Lifting and lowering movement of the boring sleeve:

After loosening the handle on the top of the left and right bases, rotate the handwheel. Through the worm wheel and worm gear pair and gear rack pair, the boring sleeve is vertically adjusted.

(3) The boring head installed on the top of the boring tool is in a small range of floating state in the vertical direction. (4) Fine adjustment of the boring bar in the horizontal direction

Loosen the clamping handle and rotate the handle. Through the screw and the boring sleeve bracket (the inner hole has an internal thread), the boring sleeve can be adjusted horizontally. After the boring sleeve is adjusted, tighten the handle.

Machine boring

When boring the cylinder block journal, first install the cylinder block on the packing block, and make the axis of the two end seat holes of the cylinder block basically coaxial with the machine spindle axis. Then, perform centering, tool setting, boring, and measurement in the following order.

1. Adjust the coordinate positions of the two boring tool boring sleeves so that the common axis of the boring sleeves is basically consistent with the common axis of the cylinder block journal seat holes. Then, loosen the boring sleeve cover handle (turn the cover to the rear) and remove the boring sleeve.

2. Insert the boring bar into the cylinder block journal seat hole, and use the initial centering sleeve to center the boring bar with the two seat holes of the cylinder block as the basis.

3. Loosen the handle adjusting handle, install the two boring sleeve clamping handles, and make the boring bar in the initial centering sleeve rotate freely in the two boring sleeves.

4. Remove the two initial centering sleeves, and install the centering gauge in the appropriate tool hole of the boring bar for fine centering.

5. After tightening the clamping handles and handles of various adjusting parts in the boring tool, use the tool setting gauge for tool setting.

6. Select the spindle speed and adjust the feed speed, use a universal joint to connect the spindle and boring bar for trial boring.

7. Use the inner diameter gauge to actually test the bored journal diameter. If the trial boring diameter exceeds the journal hole tolerance, the tool can be set again for trial boring until the tolerance requirements are met.

The auxiliary support is an additional device that enhances the cutting rigidity of the boring bar. During installation, the auxiliary support is pressed from the outside (or inside) of the cylinder block with a pressure plate. When using, first push the precisely centered boring bar back to the boring bar support, then insert it into the auxiliary boring sleeve, then restore the boring bar boring position, adjust the auxiliary support, and tighten the threaded shaft to make the boring bar rotate flexibly, and tighten the positioning handles of the auxiliary boring support.

The centering of the boring bar to the journal is carried out in two steps: initial centering and fine centering. Initial centering uses a centering sleeve, and fine centering uses a centering gauge.

To bore the predetermined journal inner diameter, the tool must be set first according to the predetermined journal inner diameter size using the tool setting gauge and the boring tool fine adjuster.

The most ideal way to determine if the bored bearing has reached the predetermined (tool setting) size is to use a special internal diameter gauge to precisely measure the bore diameter without withdrawing the boring bar (i.e., the boring tool remains stationary).

Centering bushings, centering gauges, tool setting gauges, boring tool fine tuners, and internal diameter gauges are all proprietary measuring tools of our company.

The boring process for camshaft bearings is similar to the steps for boring crankshaft bearings described above.