CN108788717B

CN108788717B - Assembling method of combined camshaft

Info

Publication number: CN108788717B
Application number: CN201810611369.4A
Authority: CN
Inventors: 何勇; 张昊
Original assignee: Chengdu Jinding Precision Casting Co ltd
Current assignee: Chengdu Jinding Precision Casting Co ltd
Priority date: 2018-06-14
Filing date: 2018-06-14
Publication date: 2021-04-06
Anticipated expiration: 2038-06-14
Also published as: CN108788717A

Abstract

The invention discloses an assembling method of a combined camshaft, which comprises the steps of connecting a first end part and a second end part with a steel pipe respectively through interference fit; the steel pipe is clamped through the transmission pin hole and the bearing hole, and the steel pipe is subjected to angle pre-positioning through the matching of the positioning pin and the positioning pin hole; rolling positioning knurls on a preset position of the steel pipe; and rotating the steel pipe to a set angle, and sleeving the cam sheet. The invention can ensure the requirements of the mounted camshaft on indexes such as static torque, dynamic torque, cycle frequency and the like.

Description

Assembling method of combined camshaft

Technical Field

The invention relates to the technical field of engines, in particular to an assembling method of a combined camshaft.

Background

The camshaft functions to control the opening and closing action of the valves. Usually, the rotational speed is still high and the camshaft is subjected to a large torque, so that the camshaft is required to have high strength and support. Especially in six-cylinder diesel engines where tensile strength, static torque, dynamic torque and cycle times are very demanding.

Six-cylinder diesel engines often require high power and high torque, and put higher demands on the combination quality of end pieces and steel pipes. Especially applied to the environment with extremely poor road environment in mountain areas in plateau and extremely high requirements on the load of automobiles. Under the condition that the automobile is fully loaded, the automobile is required to meet various road conditions, such as working conditions of climbing, emergency braking, high-speed rotation and the like, so that the requirement on the camshaft of the automobile is higher, generally, the camshaft of the automobile is required to be capable of bearing static torque of not less than 400N.m, dynamic torque of +/-250 N.m and circulation for more than 7 million times.

At present, a camshaft suitable for a diesel engine is generally formed by processing an integral bar or processing a bar after rolling in order to ensure torque and a transmission effect, the processing process is long, the production efficiency is low, and the camshaft is the integral bar or the rolled bar, the material selection is single, and the requirements of a high-bearing transport vehicle in a highland mountain area on high strength, high hardness and high wear resistance cannot be met simultaneously.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for assembling an assembled camshaft capable of withstanding extremely high tensile strength, static torque, and dynamic torque, and also capable of withstanding high cycle times.

In order to solve the technical problems, the invention adopts the following technical scheme:

provided is an assembling method of a combined camshaft, which comprises the following steps:

s1, connecting the first end part and the second end part with the steel pipe respectively through interference fit;

s2, clamping the steel pipe through the transmission pin hole and the bearing hole, and matching the steel pipe with the positioning pin hole through the positioning pin to pre-position the steel pipe in an angle;

s3, rolling, positioning and knurling at the preset position of the steel pipe;

s4, rotating the steel pipe to a set angle, and sleeving the cam sheet;

and S5, repeating the steps S3 and S4 until all the cam pieces are installed.

Further, the specific method for connecting the first end part and the second end part with the steel pipe in the interference fit mode respectively comprises the following steps of:

s1, connecting the outer annular knurl of the first end part with the inner pipe of the steel pipe in an interference fit manner until the positioning ring of the first end part abuts against the steel pipe;

and S2, connecting the smooth excircle of the second end part with the inner pipe of the steel pipe in an interference fit manner until the end part of the second end part, which deviates from one side of the steel pipe, is flush with the end part of the steel pipe.

The assembling method of the combined camshaft provided by the invention has the main beneficial effects that:

when the cam sheets are installed, the transmission pin holes are matched with the bearing holes to axially position the steel pipe, so that when the steel pipe is rotated and the cam sheets are installed, the axial positions of all the cam sheets can be ensured to meet the requirements; the steel pipe is axially positioned through the positioning pin hole, so that the pin hole and the cam sheet have set relative angle positions to meet the requirements.

Drawings

Fig. 1 is a sectional view of an assembling method of an assembled camshaft.

Fig. 2 is a schematic view of the first end piece.

Fig. 3 is a partially enlarged view of the positioning knurls.

Fig. 4 is a side view of an assembling method of the assembled camshaft.

Fig. 5 is a graph of experimental data of a tensile strength test performed on the assembled camshaft.

The bearing comprises a first end part 1, a first end part 11, an outer circle knurl 12, a positioning ring 13, a transmission pin hole 14, a positioning pin hole 2, a steel pipe 3, a cam sheet 4, a second end part 41 and a bearing hole.

Detailed Description

The invention will be further described with reference to the accompanying drawings in which:

as shown in fig. 1, it is a structural schematic diagram of an assembled camshaft.

The combined camshaft comprises a steel pipe 2, wherein two ends of the steel pipe 2 are respectively connected with a first end part 1 and a second end part 4 in an interference fit manner, an outer annular knurl 11 is arranged at the connecting part of the first end part 1 and the steel pipe 2, as shown in figure 2, a positioning ring 12 is arranged at the rear side of the outer annular knurl 11, a transmission pin hole 13 is formed in the middle of one side of the first end part 1, which deviates from the steel pipe 2, and a positioning pin hole 14 is formed in the position, close to the transmission pin hole 13, in parallel; the connecting part of the second end part 4 and the steel pipe 2 is a smooth excircle, the outer diameter of the smooth excircle is larger than the inner diameter of the steel pipe 2 at the adjacent position, and the position of the end part of the second end part 4 corresponding to the transmission pin hole 13 is provided with a bearing hole 41.

As shown in fig. 3, a positioning knurl is rolled on the outer diameter of the steel pipe 2, and the steel pipe 2 is connected with the inner hole of the cam plate 3 through the positioning knurl by interference fit.

The number of the cam pieces is six, and each group is at least one; the relative distance and steering angle of each set of cam lobes are the same as shown in fig. 4.

Wherein, the positioning knurls and the excircle knurls 11 are longitudinal knurls; the outer annular knurls 11 are gear-shaped, the pitch of the outer annular knurls 11 is 1mm, the diameter of the outer annular knurls is 35.75 +/-0.05 mm, the tooth tops of the outer annular knurls are arc-shaped, the width of the tooth tops of the outer annular knurls is 0.23mm, the tooth roots of the outer annular knurls are arc-shaped, the radius of the tooth roots of the outer annular knurls is 0.1 mm.

The following tests were carried out to verify the performance of the camshaft provided by the invention:

in order to meet the requirements of high-bearing transport vehicles in plateau mountain areas on high strength, high hardness and high wear resistance, the camshaft provided by the invention is subjected to a static torque and dynamic torque bearing capacity verification test.

As shown in table 1, in order to ensure that the camshaft can bear a static torque of 400n.m or more, the connection between the steel pipe 2 and the first end member 1 is tested, a torsion test is performed with a target static torque of 500n.m, and in repeated tests, the failure torques of the structure provided by the present invention are all greater than the rated static torque.

TABLE 1

Serial number

Rated static torque

Failure torque

Determination

Serial number

Rated static torque

Failure torque

Determination

1

500N.m

623N.m

Qualified

8

500N.m

594N.m

Qualified

2

500N.m

581N.m

Qualified

9

500N.m

571N.m

Qualified

3

500N.m

540N.m

Qualified

10

500N.m

616N.m

Qualified

4

500N.m

617N.m

Qualified

11

500N.m

583N.m

Qualified

5

500N.m

589N.m

Qualified

12

500N.m

549N.m

Qualified

6

500N.m

547N.m

Qualified

13

500N.m

577N.m

Qualified

7

500N.m

611N.m

Qualified

14

500N.m

562N.m

Qualified

As shown in table 2, in order to ensure that the camshaft can bear a dynamic torque of ± 250n.m or more, a torsion test is performed on a test target of the connection between the steel pipe 2 and the first end member 1 with a dynamic torque of ± 400n.m, and in order to ensure that the cycle is 7 million times or more, after the camshaft is assembled, a dynamic torque test is performed to ensure that the camshaft structure is not loosened after 7 million cycles. In repeated tests, the structure provided by the invention can ensure that the looseness does not occur, so that the requirement can be determined to be met.

TABLE 2

For the camshaft after the assembly is finished, because the cam plate 3 is connected with the steel pipe 2 in an interference fit manner through the positioning knurls, the requirement on the cam plate 3 is lower than that of the steel pipe 2, and the camshaft can at least bear static torque not less than 400N.m, can bear dynamic torque of +/-250 N.m and can be circulated for more than 7 million times. As shown in tables 3 and 4, the structures for performing the static torque verification test and the dynamic torque verification test are shown, and it can be seen from the tables that the structure provided by the present invention satisfies the setting requirements.

TABLE 3

Serial number

Rated static torque

Failure torque

Determination

Serial number

Rated static torque

Failure torque

Determination

1

400N.m

430N.m

Qualified

11

400N.m

436N.m

Qualified

2

400N.m

483N.m

Qualified

12

400N.m

439N.m

Qualified

3

400N.m

445N.m

Qualified

13

400N.m

500N.m

Qualified

4

400N.m

472N.m

Qualified

14

400N.m

455N.m

Qualified

5

400N.m

479N.m

Qualified

15

400N.m

473N.m

Qualified

6

400N.m

448N.m

Qualified

16

400N.m

420N.m

Qualified

7

400N.m

451N.m

Qualified

17

400N.m

433N.m

Qualified

8

400N.m

462N.m

Qualified

18

400N.m

437N.m

Qualified

9

400N.m

434N.m

Qualified

19

400N.m

450N.m

Qualified

10

400N.m

429N.m

Qualified

20

400N.m

442N.m

Qualified

TABLE 4

In practical use, the steel pipe 2 of the camshaft has the requirement of tensile strength, and the tensile strength of the shaft of a six-cylinder diesel engine is not less than 700MPa usually, so that the carbon content of the steel pipe 2 is 0.2-0.25%, and a metal tensile test is carried out. As shown in fig. 5 and table 5, the relationship between the tensile strength Rm and the tensile force Fm and the cross-sectional area So is Rm ═ Fm/So, and therefore, the calculated maximum tensile strength Rm is greater than 700MPa, and the structure provided by the present invention satisfies the set requirements.

TABLE 5

The following is an assembling method of the above-mentioned assembled camshaft, which includes the steps of:

and S1, connecting the first end part 1 and the second end part 4 with the steel pipe 2 respectively through interference fit.

Further, the above-mentioned connection includes the following steps:

s1-1, connecting the outer annular knurl 11 of the first end part 1 with the inner pipe of the steel pipe 2 in an interference fit manner, and enabling the positioning ring 12 of the first end part 1 to abut against the steel pipe 2.

The steel pipe 2 and the first end part 1 are respectively centered and positioned by a tool, and then the first end part is axially moved, so that the first end part 1 is connected with the steel pipe 2.

S1-2, connecting the outer circle of the second end part 4 after precision machining and shaping with the inner tube of the steel tube 2 after boring by interference fit until the end part of the second end part 4 deviating from the steel tube 2 is flush with the end part of the steel tube 2.

And S2, clamping the steel pipe 2 through the transmission pin hole 13 and the bearing hole 41, and matching the positioning pin with the positioning pin hole 14 through the positioning pin to pre-position the angle of the steel pipe 2.

The steel pipe 2 is driven to rotate by the rotation of the three-jaw chuck, so that the pre-positioning of the angle is carried out.

S3, rolling, positioning and knurling the steel pipe 2 at a predetermined position.

The processing is carried out at only one position each time, the knurling tool is used for rolling, and the transmission pin hole 13 is matched with the bearing hole 41 to prevent the displacement, so that the processing precision is ensured.

And S4, rotating the steel pipe 2 to a set angle, and sleeving the cam piece 3.

And sleeving the cam sheet 3 into the machined positioning knurl position, and connecting the cam sheet and the positioning knurl through interference fit.

And S5, repeating the steps S3 and S4 until all the cam pieces 3 are installed.

The number of the cam pieces can be 6, 12 and 18, and the cam pieces are respectively and uniformly distributed at the positions of 6 cylinders.

The above description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.

Claims

1. An assembling method of a combined camshaft is characterized by comprising the following steps:

s1, connecting the first end part (1) and the second end part (4) with the steel pipe (2) through interference fit respectively;

connecting the outer annular knurl (11) of the first end part (1) with the inner pipe of the steel pipe (2) in an interference fit manner until the positioning ring (12) of the first end part (1) abuts against the steel pipe (2);

connecting the smooth excircle of the second end part (4) with the inner pipe of the steel pipe (2) in an interference fit manner until the end part of the second end part (4) deviating from one side of the steel pipe (2) is flush with the end part of the steel pipe (2);

the outer annular knurls (11) are longitudinal knurls; the outer annular knurls (11) are gear-shaped, the pitch of the outer annular knurls (11) is 1mm, the diameter of the outer annular knurls is 35.75 +/-0.05 mm, the tooth tops of the outer annular knurls are arc lines and are 0.23mm in width, the tooth roots of the outer annular knurls are arc lines and are 0.1mm in radius, and the tooth form angle is 87 degrees;

the middle part of one side of the first end part (1) deviating from the steel pipe (2) is provided with a transmission pin hole (13), and the end part of the second end part (4) corresponding to the transmission pin hole (13) is provided with a bearing hole (41);

s2, clamping the steel pipe (2) through the transmission pin hole (13) and the bearing hole (41), and positioning the steel pipe (2) in an angle mode through the matching of the positioning pin and the positioning pin hole (14);

s3, rolling, positioning and knurling at the preset position of the steel pipe (2);

s4, rotating the steel pipe (2) to a set angle, and sleeving the cam sheet (3);

and S5, repeating the steps S3 and S4 until all the cam sheets (3) are installed.