JPH0541376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for press-fitting a drive shaft into a differential device.

(Prior art) This type of drive shaft is shown in Fig. 4 with reference numeral 1.
As shown, the side gear 2 of the differential gear is press-fitted and assembled into the pinion shaft 4 with the serration portion 3 as a guide until it bottoms out. Also, the drive shaft 1 assembled in this way
The snap spring 5 attached to the groove at the tip thereof engages with the side gear 2 to prevent it from coming off. By the way, the drive shaft 1 is usually assembled to the differential device in-line, and therefore,
The press-fitting device for the drive shaft is required to be easy to handle and have excellent press-fitting accuracy.

FIG. 5 shows an example of a press-fitting device that satisfies such requirements, and has the same basic structure as the device shown in Japanese Utility Model Application Publication No. 57-197427. In the figure, reference numeral 11 denotes a cylinder (hydraulic cylinder) fixed on a frame 12, and a fixed arm 13 extending from the frame 12 is arranged at the base end side of the cylinder 11. Furthermore, the fixed arm 1 is attached to the tip of the piston rod 14 of the cylinder 11.
A movable arm 15 is fixed so as to face the frame 12, and the movable arm 15 can slide along a slide guide (not shown) provided on the frame 12. That is, the movable arm 15 can move forward and backward with respect to the fixed arm 13 by the operation of the cylinder 11, and thereby the left and right drive shafts 1, 1 (fourth If the fixed arm 13 and movable arm 15 are engaged with each other as shown in FIG.
A reaction force is applied to both arms, and the drive shaft comes to be press-fitted into the ring gear 2 (FIG. 4).

However, conventionally, it has been determined whether or not the drive shaft has been completely press-fitted using the fixed arm 13.
The span L between the cylinder 11 and the movable arm 15 is measured with a linear sensor (pulse scale or differential transformer) 16 attached to the frame 12, and the hydraulic pressure rise caused by the drive shaft bottoming out on the pinion gear is measured by the cylinder 11 and the hydraulic pressure. unit 17
The hydraulic header 19 installed in the piping 18 connecting the was.

(Problems to be Solved by the Invention) However, in the conventional press-fitting device described above, the hydraulic pressure applied to the cylinder 11 is measured by the hydraulic pressure sensor 20, and this is converted into a press-fitting load. Dynamic resistance, flow resistance of hydraulic fluid in hydraulic piping, etc. are also calculated as the press-fit load, which poses a problem in that an accurate press-fit load cannot be obtained.

This is especially true for Snap Spring 5 (Figure 4).
This has an extremely important influence when determining whether or not the ring gear 2 is reliably opened within the ring gear 2 and is generating a predetermined holding force in the direction in which the drive shaft 1 is pulled out. That is, in order to determine the holding force, it is necessary to apply a load to the drive shaft 1 in a predetermined pulling direction, but this pulling load is usually very small compared to the press-fitting load (maximum of about 1000 kgf), and is approximately 100 kgf.
~150Kgf (Incidentally, the external force in the pull-out direction during actual driving is about 50Kgf), and the inaccuracy of the above-mentioned detected oil pressure has a large effect on this pull-out load, and as a result, the holding force cannot be accurately determined. Become.

Of course, this problem can be solved if an actuator that can stably supply such a small thrust is used in conjunction with the hydraulic cylinder 11, but as mentioned above, the increase in weight and size of the press-fitting device increases the production line. This was unfavorable from a structural standpoint, and the use of the above press-fitting device to determine the pull-out load had to be abandoned.

(Means for Solving the Problems) In order to solve the above problems, the present invention disposes a fixed arm extending from the frame on the base end side of a cylinder fixedly installed on the frame, and also provides a fixed arm extending from the frame. A movable arm, which is movably disposed on the cylinder opposite to the fixed arm, is connected to the end of the piston rod, and when the cylinder is actuated, the two arms are moved toward and away from each other, and the two arms are connected to the drive shaft. In a driveshaft press-fitting device that applies a load in the press-fitting direction and the pulling-out direction to the differential device,
A load cell is interposed in a connecting portion between the piston rod and the movable arm, and the load cell has one surface in contact with both an end surface of the piston rod and a back surface of the movable arm, which are inserted through the movable arm and seen from the back side thereof. The gist is that the piston rod and the movable arm are each tightened and fixed using a fastening member.

(Function) In the drive shaft press-fitting device configured as described above, a compressive load is applied to the load cell both when press-fitting the drive shaft and when applying a load in the pull-out direction to the drive shaft.
The load cell makes it possible to accurately measure the press-in load and the pull-out load, thereby significantly improving the reliability of press-fit quality assurance. Further, since the load cell is simply attached to the end of the piston rod, the device does not increase in weight or size, and good operability can be maintained.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

1 and 2 show the structure of a drive shaft press-fitting device according to the present invention. In addition, in this figure, the same parts as those shown in FIG.
The feature of this embodiment is that a movable arm 15 is fitted to the end of the piston rod 14 of the cylinder 11.
A load cell 25 is attached so as to be in contact with the end face of the load cell 4, and a peak detector 26 for displaying the load is connected to the load cell 25.

More specifically, the piston rod 14 has a small diameter part 14a having a thread at its end, and this small diameter part 14a projects to the back of the movable arm 15, and a stepped surface 14b connected to the small diameter part 14a is formed from the back of the movable arm 15. It sticks out slightly. The load cell 25 is sensitive in the compression direction and is fitted into the small diameter portion 14a of the piston rod 14.
The piston rod 14 is fixed with one end in contact with the stepped surface 14b of the piston rod 14 by a nut 27 that is screwed into the small diameter portion 14a. Also, the load cell 2
5 is also fixed by a bolt 28 which is screwed into the movable arm 15 with the same end in contact with the movable arm 15.

That is, the load cell 25 is connected to the movable arm 15
moves in the direction A and press-fits the drive shaft 1 (see FIG. 4), stress is applied between the movable arm 15 and the nut 27, while the movable arm 15 moves in the direction B and press-fits the drive shaft 1 (see FIG. 4). When applying pressure in the withdrawal direction, the end 1 of the piston rod 14
4b and the bolt 28 are subjected to stress.

That is, when press-fitting the drive shaft 1,
A compressive load is applied to the load cell 25 both when a load is applied to the drive shaft 1 in the pulling direction.

With this configuration, the fixed arm 13 and the movable arm 15 are engaged with the left and right drive shafts 1,
When the piston rod 14 of the cylinder 11 is actuated toward the contraction side, a reaction force is applied to both arms, and the drive shaft is press-fitted into the side gear 2 (FIG. 4). The press-fitting load at this time is measured by the load cell 25, and it is determined whether the drive shaft 1 has accurately bottomed out on the pinion gear 4 (FIG. 4). After the press-fitting is completed, the piston rod 14 is operated to the extension side, and a constant load is applied to the drive shaft 1 for a certain period of time while checking with the load cell 15 to check whether the holding force of the snap spring 5 (Fig. 4) is appropriate. judge. In addition, in the case of the said determination, the span L of the fixed arm 13 and the movable arm 15 is measured with the linear sensor 16 attached to the frame 12, and the determination is aided similarly to the past.

By the way, as described above, the thrust force required by the cylinder 11 in the pulling direction is very small compared to the thrust force in the press-in direction, so it is desirable to supply hydraulic pressure to the cylinder 11 as stably as possible. Therefore, in this embodiment, the hydraulic unit 30 that controls the operation of the cylinder 11 is provided with a plurality of solenoid valves 32 to 38 in the hydraulic circuit connecting the oil tank 31 and the cylinder 11, as shown in FIG. 3a. A dimension shift cylinder 39 is interposed therebetween, and by switching these, the movable arm 15 is configured to be able to carry out low-pressure advance, high-pressure advance, low-pressure retreat, high-pressure retreat, and high-pressure fixed-size retreat.

As a result, if you want to apply a small load in the pulling direction to the drive shaft, that is, if you want to perform low-pressure retraction of the movable arm 15, the solenoids sol.1, sol.3 of the solenoid valves 32, 33, 35, 37, and 38 , sol.6, sol.8 and sol.9
, and open the circuit shown in bold line in the figure. As a result, the hydraulic oil pumped by the hydraulic pump 40 is reduced to an appropriate pressure by the pressure reducing valve 41, passes through various valves, adjustment valves, etc., and is loaded with the same hydraulic pressure to the head and rod side chambers of the hydraulic cylinder 11 by the four-way valve 43. It branches as shown in the figure, and reaches the cylinder 11. As a result, a differential pressure is generated within the cylinder 11 due to the difference in the pressure receiving areas of the pistons within the cylinder 11, and the piston rod 1
4 extends and causes the movable arm 15 to slide. The thrust generated here is the thrust obtained by subtracting the sliding resistance of the piston from the differential pressure, but this value is adjusted by the diameter of the pressure reducing valve 41 and the piston rod 14, etc. As a result, a small thrust in the drive shaft removal direction can be obtained with a small adjustment range in which the amount of change in sliding load is small in response to changes in the working oil pressure after passing through the pressure reducing valve 41.

In addition, as shown in FIG. 3b, the low pressure movement of the movable arm 15 is performed by
Solenoids 35, 37 and 38 sol.2, sol.
4, sol. 5, sol. 8, and sol. 9 are conducted, the circuit shown in the bold line in the figure is opened, and the set pressure of the pressure reducing valve 42 is applied to the chamber on the rod side of the hydraulic cylinder 11. As shown in Figure 3c, the solenoids of solenoid valves 33, 35, 37 and 38
Conducting sol.2, sol.5, sol.8 and sol.9,
Open the circuit indicated by the thick line in the figure, and press the hydraulic cylinder 11.
The set pressure of the hydraulic pump 40 is applied to the chamber on the rod side of the valve, and the high pressure retraction is performed by applying the set pressure of the hydraulic pump 40 to the chamber on the rod side of the valve, and the solenoids sol. 3, sol. 8 and sol. The circuit shown in bold line in the figure is made conductive, and the set pressure of the hydraulic pump 40 is applied to the chamber on the head side of the hydraulic cylinder 11.Furthermore, high pressure constant retraction is performed using the solenoid valve 36 as shown in Fig. 3e. , 37 and 38 solenoids
Connect sol.7, sol.8 and sol.9, open the circuit shown in bold line in the figure, and connect the fixed size shift cylinder 39.
The oil inside is supplied to the chamber on the head side of the hydraulic cylinder 11.

(Effects of the Invention) As explained above in detail, the drive shaft press-fitting device according to the present invention directly measures the load with one load cell that is sensitive in the compression direction, so that the press-fitting load and the pull-out load can be easily measured. Accurate measurement becomes possible, which significantly improves the reliability of press-fit quality assurance.Additionally, the slight modification of installing one load cell at the connection between the piston rod and the movable arm reduces the weight of the device. This eliminates the problem of increase in size and size, resulting in the effect that good operability can be maintained.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the structure of a drive shaft press-fitting device according to the present invention, Fig. 2 is a cross-sectional view showing a part thereof in an enlarged manner, and Figs. FIG. 4 is a circuit diagram showing the structure and operating state, FIG. 4 is a cross-sectional view showing how the drive shaft is assembled to the differential device, and FIG. 5 is a schematic diagram showing a conventional drive shaft press-fitting device. DESCRIPTION OF SYMBOLS 11... Cylinder, 12... Frame, 13... Fixed arm, 14... Piston rod, 15... Movable arm, 25... Load cell.

Claims (1)

[Claims] 1. A fixed arm extending from the frame is arranged on the base end side of a cylinder fixedly installed on the frame, and at the end of the piston rod of the cylinder,
A movable arm movably disposed on the cylinder facing the fixed arm is connected, and the two arms are moved toward and away from each other by the operation of the cylinder, so that the two arms press the drive shaft into the differential gear in a direction. In a press-fitting device for a drive shaft that applies a load in the removal direction, a load cell is interposed in the connecting portion between the piston rod and the movable arm, and the load cell is inserted through the movable arm and seen from the back side thereof. A press-fitting device for a drive shaft, characterized in that the piston rod and the movable arm are fastened and fixed to each of the piston rod and the movable arm using fastening members, with one surface in contact with both the end surface of the piston rod and the back surface of the movable arm.