Coaxiality measuring device

Abstract

To realize a coaxiality measurement device capable of suppressing deterioration of accuracy in measuring coaxiality between a reference hole arranged in a measured member and a measured part.SOLUTION: A coaxiality measurement device (20) includes: a reference shaft (22) to be inserted into a reference hole of a measured member; a gauge head (24) to be rotated around a central axis of the reference shaft (22) while having contact with a measured part of the measured member; a measurement device (23) for measuring a displacement amount of the gauge head (24); and a jig (31) having a horizontal surface (32) on which the measured member is placed. The reference shaft (22) includes: a shaft part (22a) to be inserted into the reference hole; and a tapered part (22b) to have contact with the horizontal surface (32) of the jig (31). A tapered angle (θ1) of the tapered part (22b) is double or less of an angle formed between the central axis of the reference hole of the measured member in a state of placement on the horizontal surface (32) of the jig (31) and the horizontal surface (32) of the jig (31).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a coaxiality measuring device, for example, a device for measuring the coaxiality between a reference hole provided in a member to be measured and a measured part consisting of an axis or hole provided in the member to be measured. [Background technology]

[0002] For example, in order to maintain the airtightness of the engine combustion chamber and the engine performance, a valve seat and a valve stem guide provided in the engine cylinder head are required to have high accuracy of concentricity.

[0003] The concentricity between such a valve seat and a valve stem guide can be measured, for example, by using a coaxiality measuring device disclosed in Patent Document 1. The coaxiality measuring device in Patent Document 1 includes a reference shaft inserted into the valve stem guide, a probe that rotates around the central axis of the reference shaft while in contact with the valve seat, and a measuring instrument that measures the displacement of the probe, and is configured to rotate the probe while positioning a stepped portion of the reference shaft by contacting it with an end face of the valve stem guide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-317395 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present applicant has found the following problem: The coaxiality measuring device of Patent Document 1 requires that the end face of the valve stem guide be machined with high precision so as to be perpendicular to the central axis of the valve stem guide, but there is a risk that the dimensional accuracy will vary depending on the machining accuracy.

[0006] Therefore, one possible method is to place the cylinder head on a jig and bring a reference shaft into contact with the jig to measure the concentricity between the valve seat and the valve stem guide. However, depending on the shape of the tip of the reference shaft, contact between the tip of the reference shaft and the jig can cause wear on the tip of the reference shaft, which can result in a deterioration in measurement accuracy.

[0007] The present disclosure has been made in consideration of such problems, and realizes a coaxiality measuring device that can suppress deterioration in the measurement accuracy of the coaxiality between a reference hole provided in a measured member and a measured portion. [Means for solving the problem]

[0008] A coaxiality measuring device according to one aspect of the present disclosure is a device for measuring the coaxiality between a reference hole provided in a member to be measured and a measurement portion consisting of a shaft portion or a hole provided in the member to be measured, A reference shaft that is inserted into the reference hole; a probe that rotates around the central axis of the reference shaft while contacting the measured portion; a measuring device for measuring the amount of displacement of the measuring element; a jig having a horizontal surface on which the member to be measured is placed; Equipped with The reference shaft has a shaft portion that is inserted into the reference hole and a tapered portion that contacts a horizontal surface of the jig, The taper angle of the tapered portion is equal to or less than twice the angle between the central axis of the reference hole in the member to be measured and the horizontal plane of the jig when the member is placed on the horizontal plane of the jig. Effect of the Invention

[0009] According to the present disclosure, it is possible to realize a coaxiality measuring device that can suppress deterioration in the measurement accuracy of the coaxiality between a reference hole provided in a measured member and a measured portion. [Brief description of the drawings]

[0010] [Figure 1]1 is a cross-sectional view showing a state in which a cylinder head, in which the coaxiality between a valve stem guide and a valve seat is to be measured by a coaxiality measuring device of an embodiment, is placed on a horizontal surface of a jig. [Diagram 2] FIG. 2 is a diagram showing a coaxiality measuring machine of the coaxiality measuring device according to the embodiment; [Diagram 3] FIG. 3 is an enlarged view of part III in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, specific embodiments to which the present disclosure is applied will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings are appropriately simplified for clarity of explanation.

[0012] First, a configuration example of a cylinder head in which the coaxiality between a valve stem guide and a valve seat is measured by the coaxiality measuring device of this embodiment will be described. Fig. 1 is a cross-sectional view showing a state in which a cylinder head in which the coaxiality between a valve stem guide and a valve seat is measured by the coaxiality measuring device of this embodiment is placed on a horizontal surface of a jig.

[0013] 1, the cylinder head 1 has an intake port 3 and an exhaust port 4 which communicate with a combustion chamber 2. A valve seat 5 is provided on the intake port 3 on the combustion chamber 2 side. The end face of the valve seat 5 on the combustion chamber 2 side is formed with, for example, a tapered face surface 5a.

[0014] A through hole 6 communicating with the intake port 3 is formed in the cylinder head 1, and a valve stem guide 7 is inserted into the through hole 6. The valve stem guide 7 has a guide hole 7a into which the stem of the intake valve is slidably inserted.

[0015] A valve seat 8 is provided on the combustion chamber 2 side of the exhaust port 4. The end face of the valve seat 8 on the combustion chamber 2 side is formed with, for example, a tapered face surface 8a.

[0016] A through hole 9 that communicates with the exhaust port 4 is formed in the cylinder head 1, and a valve stem guide 10 is inserted into the through hole 9. The valve stem guide 10 has a guide hole 10a into which the stem of the exhaust valve is slidably inserted.

[0017] In order to measure the concentricity between the valve seat 5 and the valve stem guide 7, or between the valve seat 8 and the valve stem guide 10 of such a cylinder head 1, a coaxiality measuring device 20 of the present embodiment is used.

[0018] Next, the configuration of the coaxiality measuring device 20 of this embodiment will be described. Fig. 2 is a diagram showing a coaxiality measuring machine of the coaxiality measuring device of this embodiment. Fig. 3 is an enlarged view of part III of Fig. 2. The coaxiality measuring device 20 of this embodiment includes a coaxiality measuring machine 21 and a jig 31, for example, as shown in Figs. 1 and 2.

[0019] 2, the coaxiality measuring machine 21 includes a reference shaft 22, a measuring device 23, and a measuring probe 24. The reference shaft 22 is inserted into the guide hole 7a of the valve stem guide 7 of the cylinder head 1 or the guide hole 10a of the valve stem guide 10.

[0020] The reference shaft 22 has a basic shape of a substantially cylindrical column, and includes a shaft portion 22a and a tapered portion 22b, as shown in Fig. 2. The shaft portion 22a is inserted into the guide hole 7a of the valve stem guide 7 of the cylinder head 1 or the guide hole 10a of the valve stem guide 10. The axial length of the shaft portion 22a is longer than the axial length of the valve stem guide 7 or the valve stem guide 10.

[0021] For example, when the shaft portion 22a is inserted into the guide hole 7a of the valve stem guide 7 or the guide hole 10a of the valve stem guide 10 of the cylinder head 1 placed on the horizontal surface 32 of the jig 31 as described below, and the tapered portion 22b of the reference shaft 22 is in contact with the horizontal surface 32 of the jig 31, the diameter of all or part of the area 22c of the shaft portion 22a surrounded by the guide hole 7a of the valve stem guide 7 or the guide hole 10a of the valve stem guide 10 is approximately equal to the diameter of the guide hole 7a of the valve stem guide 7 or the guide hole 10a of the valve stem guide 10.

[0022] As a result, when region 22c of shaft portion 22a is inserted into guide hole 7a of valve stem guide 7 or guide hole 10a of valve stem guide 10, at least a portion of region 22c of shaft portion 22a can be in approximate surface contact with guide hole 7a of valve stem guide 7 or guide hole 10a of valve stem guide 10, thereby stabilizing reference axis 22.

[0023] The tapered portion 22b has a substantially conical shape as shown in Fig. 3. The taper angle θ1 of the tapered portion 22b is, for example, approximately equal to twice the angle θ2 between the central axis L1 of the guide hole 7a of the valve stem guide 7 and the horizontal surface 32 of the jig 31, or the angle θ3 between the central axis L2 of the guide hole 10a of the valve stem guide 10 and the horizontal surface 32 of the jig 31, when the cylinder head 1 is placed on the horizontal surface 32 of the jig 31 as described below.

[0024] In other words, the gradient angle θ4 formed by the central axis L3 of the reference shaft 22 and the tapered surface is approximately equal to the angle θ2 formed between the central axis L1 of the guide hole 7a of the valve stem guide 7 and the horizontal plane 32 of the jig 31, or the angle θ3 formed between the central axis L2 of the guide hole 10a of the valve stem guide 10 and the horizontal plane 32 of the jig 31.

[0025] This allows the tapered portion 22b to be in approximate linear contact with the horizontal surface 32 of the jig 31 when the shaft portion 22a is inserted into the guide hole 7a of the valve stem guide 7 or the guide hole 10a of the valve stem guide 10 of the cylinder head 1 placed on the horizontal surface 32 of the jig 31.

[0026] Measuring device 23 is, for example, a dial gauge, and measures the amount of displacement of measuring element 24. Measuring device 23 is fixed to a portion of reference shaft 22 on the opposite side to tapered portion 22b via fixing jig 25. Therefore, measuring element 24 is rotatable about central axis L3 of reference shaft 22 as reference shaft 22 rotates.

[0027] At this time, the fixing jig 25 is preferably slidable relative to the reference axis 22. The fixing jig 25 is preferably equipped with, for example, a base fixed to the reference axis 22, and an arm having the measuring device 23 fixed to its tip and fitted into the base so as to be slidable in a direction approximately perpendicular to the central axis L3 of the reference axis 22. This allows the measuring element 24 to be moved relative to the reference axis 22 in the axial direction of the reference axis 22 (i.e., the extension direction of the central axis L3 of the reference axis 22) and in a direction approximately perpendicular to the central axis L3 of the reference axis 22.

[0028] Furthermore, it is preferable that the fixing jig 25 is detachable from the reference shaft 22. This makes it possible to use a reference shaft 22 having a different diameter of the shaft portion 22a or a different taper angle θ1 of the tapered portion 22b depending on the type of cylinder head 1, thereby improving the versatility of the coaxiality measuring device 20.

[0029] As shown in FIG. 1, the jig 31 has a horizontal surface 32 on which the surface of the cylinder head 1 opposite to the combustion chamber 2 can be placed.

[0030] Next, a typical procedure for measuring the coaxiality between the valve seat 5 of the cylinder head 1 and the guide hole 7a of the valve stem guide 7 using the coaxiality measuring device 20 of this embodiment will be described. The procedure for measuring the coaxiality between the valve seat 8 of the cylinder head 1 and the guide hole 10a of the valve stem guide 10 using the coaxiality measuring device 20 of this embodiment is substantially the same.

[0031] First, the cylinder head 1 is placed on the horizontal surface 32 of a jig 31, and the combustion chamber 2 of the cylinder head 1 is arranged on the opposite side of the horizontal surface 32. Next, the shaft portion 22a of the reference shaft 22 of the coaxiality measuring device 21 is inserted into the guide hole 7a of the valve stem guide 7 of the cylinder head 1, while the tapered portion 22b of the reference shaft 22 is brought into contact with the horizontal surface 32 of the jig 31.

[0032] At this time, the diameter of all or part of the area 22c surrounded by the guide hole 7a of the valve stem guide 7 in the shaft portion 22a of the coaxiality measuring device 21 is approximately equal to the diameter of the guide hole 7a of the valve stem guide 7, so that at least a portion of the circumferential surface of the shaft portion 22a is in approximately surface contact with the circumferential surface of the guide hole 7a of the valve stem guide 7, and the central axis L3 of the reference shaft 22 is positioned so as to approximately overlap with the central axis L1 of the guide hole 7a of the valve stem guide 7.

[0033] Furthermore, since the taper angle θ1 of the tapered portion 22b of the coaxiality measuring device 21 is approximately equal to twice the angle θ2 formed between the central axis L1 of the guide hole 7a of the valve stem guide 7 and the horizontal surface 32 of the jig 31, the tapered portion 22b comes into approximate line contact with the horizontal surface 32 of the jig 31.

[0034] Next, the coaxiality measuring machine 21 is rotated while the probe 24 of the measuring device 23 in the coaxiality measuring machine 21 is brought into contact with the face surface 5a of the valve seat 5. As a result, the probe 24 rotates around the central axis L1 of the guide hole 7a of the valve stem guide 7 along the face surface 5a of the valve seat 5.

[0035] At this time, if there is a misalignment between the valve seat 5 and the guide hole 7a of the valve stem guide 7, the displacement of the probe 24 will be greater than if there is no misalignment between the valve seat 5 and the guide hole 7a of the valve stem guide 7. This makes it possible to measure the coaxiality between the valve seat 5 and the guide hole 7a of the valve stem guide 7 based on the measurement results of the measuring device 23.

[0036] Here, since the coaxiality measuring machine 21 can be rotated while the tapered portion 22b of the reference shaft 22 in the coaxiality measuring machine 21 is in approximate line contact with the horizontal surface 32 of the jig 31, the coaxiality measuring machine 21 can be rotated in a stable state. Moreover, since the tapered portion 22b of the reference shaft 22 in the coaxiality measuring machine 21 is in approximate line contact with the horizontal surface 32 of the jig 31, wear of the tapered portion 22b can be suppressed. Therefore, deterioration in the measurement accuracy of the coaxiality between the valve seat 5 and the guide hole 7a of the valve stem guide 7 can be suppressed.

[0037] In this manner, the coaxiality measuring device 20 of the present embodiment can rotate the coaxiality measuring machine 21 in a stable state. Moreover, wear of the tapered portion 22b of the reference shaft 22 in the coaxiality measuring machine 21 can be suppressed.

[0038] Therefore, it is possible to suppress deterioration in the measurement accuracy of the concentricity between the valve seat 5 of the cylinder head 1 and the guide hole 7a of the valve stem guide 7, or between the valve seat 8 of the cylinder head 1 and the guide hole 10a of the valve stem guide 10.

[0039] In addition, using a jig 31 having a horizontal surface 32, the concentricity between the valve seat 5 of the cylinder head 1 and the guide hole 7a of the valve stem guide 7, or the concentricity between the valve seat 8 of the cylinder head 1 and the guide hole 10a of the valve stem guide 10, can be measured, and there is no need to prepare a jig depending on, for example, the valve inclusion angle of the cylinder head.

[0040] Therefore, the concentricity between the valve seat 5 of the cylinder head 1 and the guide hole 7a of the valve stem guide 7, or the concentricity between the valve seat 8 of the cylinder head 1 and the guide hole 10a of the valve stem guide 10, can be measured inexpensively.

[0041] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present disclosure.

[0042] For example, the coaxiality measuring machine 21 may be of a selectable (i.e., replaceable) type for the reference shaft 22 having a different diameter of the region 22c of the shaft portion 22a or a different taper angle θ1 of the taper portion 22b depending on the shape of the cylinder head 1. This makes it possible to absorb, for example, differences in the diameter of the guide hole of the valve stem guide of the cylinder head 1 or the valve clamping angle of the cylinder head 1.

[0043] For example, in the above embodiment, the taper angle θ1 of the tapered portion 22b of the coaxiality measuring device 21 is set to be approximately equal to twice the angle θ2 formed between the central axis L1 of the guide hole 7a of the valve stem guide 7 and the horizontal plane 32 of the jig 31, or the angle θ3 formed between the central axis L2 of the guide hole 10a of the valve stem guide 10 and the horizontal plane 32 of the jig 31, but it may be less than twice that.

[0044] In this case, for example, it is easier to measure the amount of wear of the tapered portion 22b compared to when the tip of the reference shaft 22 has a spherical shape, and it is possible to prevent deterioration in the measurement accuracy of the concentricity between the valve seat 5 of the cylinder head 1 and the guide hole 7a of the valve stem guide 7, or the concentricity between the valve seat 8 of the cylinder head 1 and the guide hole 10a of the valve stem guide 10.

[0045] For example, the coaxiality measuring device 20 of the above embodiment is used to measure the coaxiality between the valve seat (measured portion) 5 of the cylinder head (measured member) 1 and the guide hole (reference hole) 7a of the valve stem guide 7, or the coaxiality between the valve seat (measured portion) 8 of the cylinder head (measured member) 1 and the guide hole (reference hole) 10a of the valve stem guide 10, but is not limited thereto. For example, it can be used for machining and adjusting a machine having an opening and closing mechanism such as a check valve, dimensional control in the manufacture of a valve or a damping force generating device having a conical orifice for flow control, or measuring the position and coaxiality of a chamfered portion provided at the mouth of a cylindrical part or a hole. [Explanation of symbols]

[0046] 1. Cylinder head 2. Combustion chamber 3 Intake port 4 Exhaust port 5 Valve seat, 5a Face 6 Through holes 7 Valve stem guide, 7a guide hole 8 valve seat, 8a face 9 Through holes 10 Valve stem guide, 10a Guide hole 20 Coaxiality measuring device 21 Coaxiality measuring machine 22 Reference axis 22a Shaft 22b Tapered section 22c Area surrounded by the guide hole of the valve stem guide in the shaft portion 23 Measuring instruments 24 Probe 25 Fixture 31 Jig 32 horizontal plane L1, L2 Center axis of the guide hole of the valve stem guide L3 Central axis of the reference axis θ1 Taper angle of the tapered part of the shaft θ2, θ3: The angle between the central axis of the guide hole of the valve stem guide and the horizontal plane of the jig θ4: Gradient angle between the central axis of the reference axis and the tapered surface

Claims

[Claim 1] A coaxiality measuring device for measuring the coaxiality between a reference hole provided in a member to be measured and a measurement portion consisting of a shaft portion or a hole provided in the member to be measured, A reference shaft that is inserted into the reference hole; a probe that rotates around the central axis of the reference shaft while contacting the measured portion; a measuring device for measuring the amount of displacement of the measuring element; a jig having a horizontal surface on which the member to be measured is placed; Equipped with the reference shaft has a shaft portion to be inserted into the reference hole and a conical tapered portion to be in contact with a horizontal surface of the jig, a diameter of the entire or part of a region of the shaft portion surrounded by the reference hole in a state where the shaft portion is inserted into the reference hole is equal to a diameter of the reference hole; a taper angle of the tapered portion is twice the angle between a central axis of a reference hole of the measured member when the measured member is placed on the horizontal surface of the jig and the horizontal surface of the jig; a coaxiality measuring device in which the coaxiality measuring device can rotate while the tapered portion is in line contact with the horizontal surface of the jig with the shaft portion inserted into a reference hole of the measured member placed on the horizontal surface of the jig.

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