JPH04224376A - Notch shape for spool and notch machining method - Google Patents

Abstract

PURPOSE:To easily and effectively improve the inching function of notches provided on a spool. CONSTITUTION:A notch shape with a V-shaped cross section is provided while the first slant face 3b is made flush and the end 3d of the second slant face 3c is curved to the first slant face 3b side. For the notch machining method, an end mill is offset from the center of a spool 1, and it is fed toward the axis (m) of the spool 1 to the preset depth of cut.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to hydraulic machinery, construction machinery,
The present invention relates to a notch shape and a notch processing method for a spool used for switching operations in industrial vehicles, special vehicles, etc., which are equipped with a mechanism operated by hydraulic pressure switching operations.

0002

2. Description of the Related Art As is well known, a spool consists of a land portion that fits into the inner periphery of a sleeve and a switching portion formed in the valley of this land portion. The relative position with respect to the sleeve is changed, thereby selectively opening the switching portion to a port provided on the sleeve side, thereby realizing flow path switching. For example, the 8th
In the switching valve shown in the figure, the land portion 102 of the spool 101
Switching parts 103, 104, 105, and 106 are provided at four locations on the top, and at least a P (high pressure) port, an A port, and a B port are opened on the inner circumference of the sleeve. for example,
To explain the functions of the both-end switching sections 103 and 106 of this spool 101, when the spool 101 moves to the right, the P port is communicated with the A port through the left switching section 103, and when the spool 101 moves to the left, it connects the P port to the A port. It serves to connect the P port to the B port through the switching unit 106.

By the way, with such a configuration, A, B
For example, if both ports are connected to opposing pressure chambers of a double-acting cylinder, when the spool 101 moves to the right or to the left, the switching unit 1 suddenly changes after moving a predetermined distance.
03 or 106 opens to the P port, and pressure liquid is rapidly introduced into the corresponding pressure chamber from the A port or B port. Therefore, although the illustrated spool 101 is excellent in that it can rapidly drive the cylinder, it is not suitable for applications that require inching operations or smooth operations.

Therefore, for such uses, it has conventionally been common practice to provide the spool 101 with a notch 107 as shown in FIGS. 9 and 10. FIG. 9 is a plan view corresponding to the periphery of the left switching portion 103 of the spool 101, and FIG. 10 is a front view thereof. If such a notch 107 is provided, for example, when the spool 101 starts moving to the right, the P port will be connected to the switching part 103.
First, open the notch 10 before fully communicating with the A port through
The throttling effect at the land portion 102 is gradually reduced from the terminal end 107a side of the spool 101, and the spool 101 can have an inching function. Note that when a notch is provided on the right switching section 106, the notch is provided on the land section 102 on the left side with respect to the switching section 106.

[0005]

However, when providing such a notch 107, machining using a lathe is generally difficult, and the process must be performed after the spool is manufactured using a general-purpose milling cutter or a special-purpose machine. However,
When performing milling, a disc-shaped cutter 105 as shown by the imaginary line in FIG. As shown in the figure, the cutter 105 is rectangular in plan view, and the notch width w is constant corresponding to the thickness of the cutter 105. Therefore, when the terminal end 107a of the notch 107 communicates with the P port of the sleeve, the opening area increases at a relatively high speed in proportion to the notch width w x the spool movement distance, and the inching A problem arises in which it is difficult to create a sufficiently gradual change in the aperture area required for operation. Moreover, cutter 1
The cross-sectional area of the notch 107 is determined by the depth of cut 05, and at the same time, the shape of the notch end 107a that is cut up along the radius of the cutter 105 is also uniquely determined, so there is the problem that it is difficult to manufacture a notch with arbitrary characteristics. Accompany. On the other hand, in some cases, a notch (not shown) that is V-shaped in plan view is manufactured in order to create a gradual change in the opening area, but in order to accurately process such a notch, technical skill is required. It is known to those skilled in the art that this imposes an extremely large burden in terms of man-hours and costs. Furthermore, notch 10
The fluid flowing out from the cutter 1 acts on the spool 101 with a fluid axial force proportional to the cosine of the jet angle θ, so-called flow force F, as shown in FIG.
At the notch end 107a rounded up by 05, the ejection angle θ is small because the diameter of the cutter 105 cannot be made small, and therefore the flow force F acting on the spool 101 is small.
becomes large, causing a problem that tends to impair control accuracy and stability.

[0006] The present invention has been made with attention to these problems, and an object of the present invention is to provide a spool notch shape and a notch processing method that can effectively solve these problems.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention takes the following measures.

First, the notch shape of the spool is provided in the land portion of the spool with the starting end open to the switching portion, and has a V-shaped cross section opening between the first slope and the second slope. None, the first slope is flat until the end, but the second slope is characterized in that the end is curved toward the first slope and rounded up.

[0009] In addition, as a method for machining such a notch, an end mill is arranged at a position offset in a direction perpendicular to both axes with respect to a center position where the axis of the end mill is perpendicular to the axis of the spool. From that position, the end mill is moved relative to the land portion along the axis of the spool by a predetermined depth of cut, and then the end mill is separated from the spool.

0010

[Operation] With such a notch shape, the width of the end of the notch becomes narrower and the bottom becomes shallower as the second slope curves toward the first slope. Therefore, when the spool is fitted into the sleeve, the opening area with the port can be increased very gradually from the end of the notch toward the switching section.

Furthermore, with such a notch processing method, when the end mill is fed along the axial direction of the spool, a first slope is formed at a position through which the end face of the end mill passes; A second slope is formed at a position where the outer periphery of the tip of the end mill passes. Therefore, the first slope is flush with the end thereof, but the end of the second slope is rounded up so that the end is curved toward the first slope along the radius of the end mill. Moreover, the shape of the notch is determined by two independent factors: the offset position of the end mill and the depth of cut, so the cross-sectional area of the notch can be freely controlled by combining them, and the shape of the notch end can be controlled. It also becomes possible to adjust the cross-sectional area of the notch separately. Moreover, since the end mill has a smaller radius than a milling cutter, the ejection angle at the end of the notch can be increased.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

As shown in FIG. 1, the spool 1 according to this embodiment is provided on the land portion 2, and the starting end 3a is connected to the switching portion 4.
It has a notch 3 that is open to the outside. The notch 3 has a cross section V opening between the first slope 3b and the second slope 3c.
The first slope 3b extends flat along the axis m direction of the spool 1 up to the terminal end 3d, whereas the second slope 3c has a terminal end 3d curved toward the first slope 3b. are rounded up.

[0014] With such a notch shape, the notch 3
The closer to the terminal end 3d along the cutting direction, the narrower the width between the second slope 3c and the first slope 3b, and
A notch bottom 3e formed at a position where both slopes 3b and 3c intersect becomes shallower. Therefore, if this spool 1 is used in place of the spool shown in FIG. 8, for example, the opening area with the P port will gradually increase from the cutting end 3d toward the starting end 3a. , and can exhibit almost the same inching function as a V-shaped notch.

On the other hand, in this embodiment, in order to machine such a notch, first, as shown in FIGS. 2 and 3, using a milling function generally provided in an NC lathe, An end mill 5 is disposed at a position B offset by a distance l in a direction perpendicular to both axes m and n with respect to a center position A where the axis n is orthogonal to the axis m of the spool 1. From the position B, the cutting depth d for the land portion 2 of the spool 1 is maintained as shown in FIG. 3, and along the axis m of the spool 1, as shown in FIGS. The end mill 5 is operated to feed in the two directions of the land portion (arrow Y direction). After that, the end mill 5 is separated from the spool 1 (
After rotating the spool 1 by 90 degrees (in the direction indicated by the arrow Z in FIG. 5), processing of the next notch is started.

With such a notch processing method, the tip surface 5 of the end mill 5 is
A first slope 3b is formed at the position where the end mill 5 passes, and a second slope 3c is formed at the position where the tip outer circumference 5b of the end mill 5 passes.
will be formed. Therefore, the first slope 3b is flush with the end 3d, but the second slope 3c has the end 3d flush with the outer periphery 5 of the end mill 5, as shown in FIGS.
It is curved and rounded up toward the first slope 3b along line b. Moreover, since the shape of the notch 3 is determined by two independent factors: the offset position B of the end mill 5 and the depth of cut d, the cross-sectional area of the notch 3 can be freely controlled by combining them. , it is also possible to adjust the shape of the notch end 3d independently of the cross-sectional area of the notch 3. Furthermore, notch 3
As shown in FIG. 6, the longitudinal section of the end mill 5 has a terminal end 3d which is much smaller than a milling cutter.
will be rounded up along the radius. For this reason, the ejection angle θ of the fluid is larger than in the past, and therefore the flow force F expressed by the cosine of the ejection angle θ is reduced, making it possible to improve control accuracy and stability.

Although one embodiment of the present invention has been described above, various notch shapes can be realized by changing the offset position and the depth of cut. Furthermore, by using the present invention and performing machining on one notch several times by changing the offset position and depth of cut, it is possible to realize a notch shape with a step-like change in cross-sectional area, resulting in a subtle change in the notch shape. Effective for applications that require a change in cross-sectional area. Furthermore, the end mill may be fixed and the spool may be movable. Furthermore, if the offset amount of the end mill 5 is reduced in the above embodiment, it is possible to process the jet angle θ to 90° or more as shown in FIG. 7, and the flow force can be completely reduced. It is also possible to offset them. In addition, various modifications can be made without departing from the spirit of the present invention.

[0018]

[Effects of the Invention] Since the present invention has the above-mentioned notch shape and notch processing method, basically one processing step is performed for one notch on the same machine as post-processing of the spool. This makes it possible to extremely easily manufacture a notch that has the same functionality as a conventional notch that is manufactured through multiple steps. Moreover, since the cross-sectional area of the notch and the shape of the end can be easily controlled, the degree of freedom in design is improved, and the reproducibility when producing notches with the same characteristics is also improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a notch shape showing one embodiment of the present invention.

FIG. 2 is a perspective view showing an embodiment of the present invention during notch processing.

FIG. 3 shows an embodiment of the present invention, and is a horizontal and vertical cross section of a spool during notch processing.

FIG. 4 is a plan view of the spool during notch processing, showing an embodiment of the present invention.

FIG. 5 is a front view of the spool during notch processing, showing an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a flow force, showing an embodiment of the present invention.

FIG. 7 is an explanatory diagram showing another embodiment of the present invention and corresponding to FIG. 6;

FIG. 8 is a sectional view of a general switching valve, showing a conventional example.

FIG. 9 is a plan view of a spool corresponding to FIG. 4, showing a conventional example.

FIG. 10 is a front view of a spool corresponding to FIG. 5, showing a conventional example.

FIG. 11 is an explanatory diagram corresponding to FIG. 6, showing a conventional example.

[Explanation of symbols]

1...Spool 2...Land part 3...Notch 3a...Starting end 3b...first slope 3c...Second slope 3d...Terminal 4...Switching section 5...End mill A...Center position B...Offset position d...Depth of cut m...Axle center of spool n...Axle center of end mill

Claims (2)

[Claims] Claim 1: A notch provided in a land portion of a spool and having a starting end open to a switching portion, the notch having a V-shaped cross section opening between a first slope and a second slope, the first slope being The notch shape of the spool is characterized in that it is flush to the end, but the second slope is rounded up with the end curved toward the first slope. Claim 2: The end mill is disposed at a position offset in a direction perpendicular to both axes with respect to a center position where the axis of the end mill is perpendicular to the axis of the spool, and the spool is spooled with a predetermined depth of cut from that position. 1. A method for notching a spool, which comprises performing a relative feeding motion of an end mill in the direction of a land along the axis of the spool, and then separating the end mill from the spool.