JPH0451968Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The disclosed technology is applicable, for example, to accurately forming a tapered portion at the inner end of a pair of concentric circular holes, such as the piston pin hole of a piston of an internal combustion engine. It belongs to the technical field of the structure of processing equipment used for.

Therefore, this invention involves moving a plurality of tapered rollers radially in and out in the circumferential direction facing a predetermined position of a pair of concentric circular holes in a workpiece, such as a pair of pin holes in a piston of an internal combustion engine. This invention relates to a taper processing device in which a tapered roller is pressed against a circular hole by inserting a freely provided holding cylinder and an internal mandrel to perform a conical burnishing process to form a tapered part. A holding cylinder having a metal fitting is inserted into the drive device in a state in which it is biased in the circular hole insertion direction by an elastic spring for controlling the thrust force of the mandrel, and is engaged with the workpiece through a stopper, and at the same time, an elastic spring is applied to the drive device. This invention relates to a processing device that rotates and pushes a mandrel into a holding cylinder using a stopper and performs conical burnishing using a taper roller, thereby forming a tapered portion in one circular hole with high accuracy within a set tolerance.

<Prior Art> As shown in FIGS. 5 and 6, a piston 1 of an internal combustion engine installed in an automobile, etc. has a piston pin for connecting a connecting rod (not shown) having a set diameter inserted into a predetermined diameter portion of the piston 1. A pair of left and right pin holes 2, 2 are bored.

When the fuel burns explosively in the cylinder, the piston 1 is momentarily subjected to a huge load, so the piston 1 curves at the center in a direction that protrudes downward in Figure 5, even if it is small. Also, although the piston pin can be bent slightly at the free end, since the connecting rod is connected at the center, the inner exit edge A of each pin hole 2 of the piston 1 is bent. There is a risk that large compressive stress will be concentrated.
In particular, if stress concentration is repeated frequently, fatigue may occur synergistically.

To prevent this phenomenon, as shown in Figure 6,
In each edge part A, a slightly tapered part 3 having a tapered angle of inclination θ that widens toward the axis of the pin hole 2 is formed by conical burnishing of the prepared hole after the primary cutting process. .

In this process, it is necessary to keep the amount of burnishing constant regardless of the diameter of the pilot hole.

Incidentally, for convenience of illustration, the inclination angle θ is exaggerated.

To perform the conical burnishing process on each pin hole 2, the pair of pin holes 2 and 2 may be machined separately or at the same time. A conventional taper processing tool 4 is shown for forming a taper part 3 at the edge A of the hole 2 by conical burnishing on the lower hole, and a cylindrical holding cylinder 5 has a large number of taper rollers at its tip. A predetermined number of slits 7, 7, 6, 6, .
A tapered portion 8 is formed at the end portion of the roller 6 that is rotatably fitted in the circumferential direction, so that each tapered roller 6 is pressed against the tapered portion 3 from the inside without slack. A mandrel 9 to be obtained can be attached thereto.

In order to form a taper part 3 having an angle θ at the exit part A of the pin hole 2 of the piston 1 using the conventional taper processing tool 4, as shown in FIG. After inserting the holding cylinder 5 from which the mandrel 9 has been relatively pulled out slightly into the pin hole 2 of the one side until the taper rollers 6, 6... are positioned inside the exit edge part A, insert the mandrel 9 while rotating it, and A collet chuck 10 for centering the coaxial center is set in the pin hole 2 of.

Therefore, each tapered roller 6 is pushed outward in the radial direction by the tapered portion 8 of the mandrel 9 and rotates around itself while being pressed against the inner surface of the pin hole 2, and the surface of the exit portion A of the pin hole 2 is plastically deformed and smoothed. The diameter of the tapered portion 3 expands slightly as it becomes larger, and the tapered portion 3 is formed with compressive residual stress.

Similarly, the tapered portion 3 can also be formed at the exit portion A of the pin hole 2 on the right side of the figure.

Moreover, the embodiment shown in FIG. 10 has a pair of pin holes 2, 2.
It is a taper processing tool 4' that simultaneously processes both sides, and has a different structure from the above-mentioned taper processing tool 4. The structure is such that the parts corresponding to the head of one of the holding cylinders 5 are coaxially connected to each other symmetrically, and therefore, the head of the holding cylinder 5' has two rows of opposing rows. Tapered rollers 6, 6, . . . arranged in an annular manner are arranged in the same manner as described above, and
Two tapered portions (not shown) similar to the tapered portion 8 described above are formed symmetrically in the axial direction on one mandrel 9' housed in the mandrel 9'.

In order to perform conical burnishing on both pin holes 2, 2 at the same time using such a processing tool 4', a holding cylinder 5' is used.
are inserted into the predetermined positions of both the left and right pin holes 2, 2 of the piston 1 and moved left and right while rotating the mandrel 9', the taper rollers 6, 6'... simultaneously rotate and close the pin holes 2, 2. 2,2 edge part A,A
The tapered portions 3, 3 can be formed at the same time.

<Problem to be solved by the invention> However, in the former case where a taper processing tool 4 is used to taper the exit portion A from one side of the pin holes 2, 2 shown in FIG.
2 is machined separately, it is difficult to make both tapered parts 3, 3 coaxial. To deal with this, as shown in Fig. 9, a pin hole 2 on the other side is used for positioning. Correct chuck 10
This has the disadvantage of requiring the use of complex jigs and high costs.

On the other hand, the latter taper processing tool 4' shown in FIG.
When using, both tapered parts 3, 3 can easily become coaxial, and the jig structure can be simplified, but in order to equalize the machining allowance of both tapered parts 3, 3, There was a problem in that it was necessary to delicately manipulate the tube 5' and the mandrel 9', making the adjustment cumbersome.

By the way, it is known that the width size of the tapered portion 3 of the pin hole 2 is determined by the following four points.

That is, as shown in FIG. 11, one is the straight part 11 of the pin hole 2 of the piston 1 of the taper roller 6.
The position width 12 of the forward end in the axial direction relative to The inner diameter of the hole 2 is 15. Of these, the position width 12 of the tapered roller 6 in the axial direction with respect to the piston 1 is
and the expansion amount 13 of the tapered roller 6 are determined by the positioning accuracy of the holding device with respect to the processing tool, and are determined by the number of allowable tolerances of the width of the tapered portion 3.
There is no problem since it can be made sufficiently small compared to mm, but the inner diameter of the pin hole 2 of the piston 1 is 15
Since the taper angle θ of the machining angle of the exit portion A of the piston 1 is in units of minutes, considering the manufacturing error 14 of the taper angle θ of the taper roller 6, the width of the taper portion 3 is teeth
Since it depends on tanθ, its influence on processing accuracy can be said to be extremely large.

Therefore, the inner diameter 15 of the pin hole 2 has a tolerance on the order of microns in the primary processing boring, etc. in the stage before taper processing, but when this is considered in terms of tanθ, the influence of the tapered portion 3 is on the order of several mm. This alone accounts for most of the tolerance of the taper portion 3, and to deal with this, the expansion amount 13 of the taper roller 6 or the position width 12 of the forward end of the taper roller 6 is adjusted according to the inner diameter 15 of the pin hole 2. For this purpose, the inner diameter of pin hole 2 should be changed to 15
The process of measuring is indispensable, and it has the drawback that it becomes extremely complex as a processing system.The manufacturing and control of the entire device is complicated and difficult, resulting in high costs. There was also the disadvantage of becoming

There is also an invention disclosed in JP-A No. 54-120273, in which the amount of burnishing by conical burnishing is made constant regardless of the diameter of holes such as piston pin holes (that is, the roller expansion pressure is kept constant).
In response to this requirement, this is basically prior art in that the absorption of variations in pore diameter is controlled by using the load that presses the taper roller against the workpiece as a thrust force, rather than by controlling the position of the mandrel and holding cylinder. .

However, as a specific technology, this prior art directly detects the main shaft thrust force and uses fluid for control, so the thrust force detection device, pressure detection equipment, solenoid valve, and their control electric circuits, etc. Complex control equipment is required, management and maintenance are cumbersome, and there are many problems with reliability and durability.

The purpose of this invention is to solve the technical problem of conical burnishing of the tapered part of the end of the piston pin hole of a workpiece such as a piston based on the above-mentioned conventional technology, and to Regardless of the size of the circular hole, the taper part can be formed with high accuracy within the set tolerance,
It is an object of the present invention to provide an excellent taper processing device that can improve the reliability of product accuracy and is beneficial to the field of processing technology in the machine manufacturing industry.

<Means for solving the problem> In order to solve the above-mentioned problem, the structure of this invention, which is based on the scope of the above-mentioned utility model registration claim, is based on a pair of concentrically formed circles of the workpiece. A plurality of tapered rollers of the same size are slidably fitted into one side of the hole and held through a corresponding slit which is provided in an annular shape parallel to the axis of the circular hole in the circumferential direction and can move forward and backward in the radial direction of the circular hole. In the taper machining device, the holding cylinder has a mandrel that is slidable in the holding cylinder and has a tapered portion at the tip that engages each tapered roller from the inside. A guide fitting fitted into the other hole is integrally fixed with a tapered part formed at its tip, and the proximal end of the mandrel is slidably attached to the tip of the shaft of the drive device so as to thrust against the mandrel. A stopper of a rod that is biased in the insertion direction of the circular hole through a force control elastic spring and is mounted on the shaft and integrally extends from the base end is capable of engaging and separating from the stopper of the shaft, On the other hand, the above-mentioned holding cylinder is press-biased toward the above-mentioned circular hole so as to be able to engage and disengage freely via another elastic spring provided between the insertion hole of the workpiece holder and the drive device. This study included the following.

<Function> The tip of the holding cylinder of the tapering tool is designed to taper a pair of concentric circular holes in the workpiece simultaneously and separately by conical venishing, thereby making it easier to adjust the machining allowance. A guide fitting with a concentric circular cross section is provided, and a holding cylinder is exposed to one circular hole, and the shaft of the driving device is biased forward by an elastic spring for controlling the thrust force against the mandrel, and is set in the workpiece holding tool. Then, the plurality of tapered rollers arranged in the circumferential direction of the holding cylinder are externally moved by the tapered portion of the tip of the mandrel pushed by the stopper via the above-mentioned elastic spring provided between the stopper of the shaft and the stopper of the holding cylinder. The thrust force of the tapered roller (roller load) is
is controlled by the above-mentioned elastic spring, and while machining the taper part, the tip guide fitting of the holding cylinder is inserted into the other circular hole through its tapered part and fitted, thereby positioning and cutting the tapered part of the circular hole. In order to form taper parts in a pair of circular holes with high machining accuracy, the two taper parts formed in both circular holes are aligned concentrically and can be machined within the set tolerance range. The thrust load of the tapered roller can be controlled using only an elastic spring, eliminating the need for a thrust force detection device, a pressure detection device, an electric control circuit, etc.

<Embodiment> Next, an embodiment of this invention will be described below with reference to FIGS. 5 and 6 and based on FIGS. 1 to 4. Note that the same parts as in the drawings from FIG. 7 onwards will be described using the same reference numerals.

The illustrated embodiment has a pair of pin holes 2, 2 of a piston 1 of an internal combustion engine as a workpiece, similar to the conventional embodiment described above.
This is an embodiment in which conical burnishing is performed on the tapered portion 3 of the exit portion A, and the pair of pin holes 2, 2 of the piston 1 are respectively similar to the above-mentioned conventional embodiment.

16 is a taper machining device which constitutes the gist of this invention, and the middle part of the holding cylinder 5 with a bottom at its tip is similar to the conventional embodiment shown in FIGS. 7 and 8, and has a set number of slits in the circumferential direction. Taper rollers 6, 6, . . . of a set size are prevented from coming off in the radial direction via 7, 7, .

Inside the holding cylinder 5, a tapered part 8 with a slight angle similar to the conventional embodiment shown in FIG. 7 is formed at the tip so as to be movable concentrically in the axial direction, and is inscribed in each tapered roller 6, 6... A mandrel 9 is inserted.

Each tapered roller 6 is restricted from moving in the axial direction with respect to the holding cylinder 5 by a slit 7.
Furthermore, the mandrel 9 and the holding cylinder 5 can not only slide relative to each other in the axial direction, but also can be relatively displaced in the rotational direction, and the taper rollers 6, 6, . . . can rotate and revolve relative to the mandrel 1. It is made to be.

As shown in FIGS. 2 and 3, the tip of the holding cylinder 5 is fitted with a pin hole 2 that is slidably fitted into the pin hole 2 and has a diameter slightly smaller than that of the pin hole 2, for example, φ0.01. A guide fitting 17 having an outer diameter of about 0.04 mm has a tapered portion 18 formed at its tip, and is fixed concentrically and integrally with a bolt 19.

Then, the workpiece of the piston 1 is held in a predetermined holder 2.
0, and the insertion hole 21 of the holder 20 for the holding cylinder 5 is bored concentrically with the pin hole 2 of the workpiece 1.

On the other hand, 22 is a drive device, and a flange 24 integrally fixed with bolts 23 has a boss 25 that is concentric with the pin hole 2 of the piston 1 and the insertion hole 21 of the holder 20. A shaft 27 having a stopper 26 screwed onto the tip thereof is fixed to the boss 25 with a screw and extends integrally to the front.

And, inside the shaft 27, there is a mandrel 9.
A stopper 28 extends concentrically from the rear end.
The rod 29 screwed onto the tip is a spline,
Alternatively, it can be freely slid in the axial direction and restrained in the rotational direction by an appropriate means such as a square tube, so that it can move forward and backward, and the load (thrust force) of each tapered roller 6 can be applied between the shaft 27 and the stopper 28. A control spring 30 is interposed.

Further, a stopper 31 for the holder 20 is screwed and fixed to the large diameter part of the rear end of the holding cylinder 5, and a flange 32 is further provided at the rear end.
A flange 33 which is similarly screwed and is sheathed on the shaft 27 and fixed to the flange 24
An elastic spring 34 is interposed between the retainer 20 and the retainer 20 to hold the retainer cylinder 5 together with the stopper 31 and flange 32.
It is biased towards the side.

In addition, in the original position of the taper processing device 16,
The stopper 31 is in a separated state without contacting the holder 20, and the stoppers 28 and 26 are in a contact state.

As shown in FIG. 1, the mandrel 9 is not pushed forward by the shaft 27 integrated into the drive device 22, but by the load (thrust force) determined by the spring constant of the elastic spring 30 for thrust force control. ), and therefore the drive device 22
Therefore, as shown in FIG. 2, each tapered roller 6 moves to the edge of the pin hole 2 through the cam action caused by the advancement of the tapered portion 8 at the tip of the mandrel 9. The pressing force of the processing load is applied to the tapered portion 3 of A to cause plastic deformation, but in this case, if the inner diameter 15 of the pin hole 2 of the piston 1 is small, the amount of compression of the elastic spring 30 increases. As a result, the expansion amount 13 of the pin hole 2 decreases, and conversely, when the inner diameter of the pin hole 2 is large, the elastic spring 3
0 will decrease, and the expansion amount 13 of the pin hole 2 will increase, and as a result, the width of the tapered portion 3 will become proportional to the compression amount of the elastic spring 30 for thrust force control. Therefore, only by appropriately adjusting the mounting load of the elastic spring 30 for thrust force control, a constant amount of expansion 13 can always be secured, regardless of the manufacturing error 14 of the taper angle of the taper roller 6. Further, even without measuring the inner diameter 15 of the pin hole 2, it is possible to perform taper processing within an acceptable range of accuracy.

In the above-described configuration, when the taper processing device 16 is in its initial state, waiting at the original position, the stopper 31 does not come into contact with the holder 20, as described above.
Therefore, the elastic spring 34 is in a natural state, and the mandrel 9 is in a forward extended position with a full stroke due to the elastic spring 30, and the stopper 28 is in contact with the stopper 26. is in a state of

Therefore, when performing the taper burnishing process on the pin holes 2, 2 of the piston 1, the piston 1 is clamped in a predetermined position with the holder 20, and the axis of each pin hole 2 and the axis of the insertion hole 21 of the holder 20 are When the taper processing device 16 is started with the centers aligned, the drive device 22 moves forward and the guide tool 17 at the tip of the holding cylinder 5 passes through the tapered portion 18 into one pin hole 2.
and guide the holding cylinder 5 into the pin hole 2, and furthermore, the guide tool 17 enters the pin hole 2 on the opposite side,
The concentric state of each tapered roller 6 with respect to the pin holes 2, 2 is adjusted.

As the drive device 22 moves forward, the holding cylinder 5
The stopper 31 comes into contact with the holder 20 and stops,
Each tapered roller 6 stops at a position facing the tapered portion forming area of the work 1.

Therefore, when the drive device 22 moves forward while rotating, the mandrel 9 is able to freely slide its rod 29 in the axial direction with respect to the shaft 27, and the elastic spring 30 for thrust force control is restrained in the rotational direction. Intermediate stopper 2
As a result, each tapered roller 6 performs a taper process on the exit portion A of the pin hole 2 of the workpiece 1 while rotating and revolving on its own axis, and is moved by the elastic spring 30. The tapered portion 3 is formed by applying a rolling force through a thrust force to cause plastic deformation and applying compressive stress.

In this process, the expansion amount 13 of each tapered roller 6 is determined by the elastic spring 3 for thrust force control.
0, and regardless of the front end position of the shaft 27, when the inner diameter 15 of the pin hole 2 is small, the expansion amount 13 is proportionally small, and when the inner diameter 15 of the pin hole 2 is large, the expansion amount 13 is proportionally small. By increasing the expansion amount 13, the expansion amount 13 can be determined only by adjusting the mounting load of the elastic spring 30 for thrust force control, regardless of the influence of the accuracy of the inner diameter 15 of the pin hole 2.

Therefore, in this invention, since the initial load of the elastic spring 30 for controlling the thrust force is set in advance, the amount of expansion 13 of the tapered portion 3 by the tapered rollers 6, 6, etc. is always constant within the range of setting accuracy. can be formed.

When the machining of the tapered portion 3 of the exit portion A for one pin hole 2 is completed, the drive device 22 is retracted to separate the holding cylinder 5 and the guide tool 17 from the holder 20, and the holder 20 is removed. By rotating it by 180°, the taper portion 3 is processed at the exit portion A of the other pin hole 2 in the same manner as in the above-described process.

During this process of forming the tapered portion 3, the guide tool 17 is fitted into the other pin hole 2, so that the taper portion 3 can be processed with the pin holes 2 concentric.

In this way, the processing of the tapered portion 3 of the exit portion A of each pin hole 2 can be completed without measuring the inner diameter 15 of the pin hole 2 and without going through any complicated man-hours.
The piston 1 has been processed with the tapered part 3 of the exit part A of each pin hole 2, and the exit part A of each pin hole 2 has been precisely machined, and the part A is in a state where compressive residual stress is applied. Therefore, when the engine is assembled and put into operation, there is no problem even if the impact force is repeatedly applied to the crankshaft pin during each explosion process.

It is needless to say that the embodiment of this invention is not limited to the above-mentioned embodiment, and various embodiments may be adopted, such as attaching a ball roller to the guide, for example.

Furthermore, it goes without saying that the application of this invention is not limited to pin holes of pistons, but can be applied to circular holes of workpieces of other mechanical devices.

<Effects of the invention> As described above, according to this invention, basically, in a taper processing device that performs conical burnishing of a pair of circular holes in a workpiece, such as the exit portion of a pin hole of an engine piston, It is almost unaffected by the manufacturing error of the taper roller that directly performs the machining, and there is no need to measure the inner diameter of each circular hole every time the machining is performed, so concentricity is always maintained when machining a pair of circular holes. The excellent effect is that the number of processes is reduced, the taper process can be performed smoothly, and the accuracy error of the product can be kept within a certain range.

Therefore, the load (thrust force) on the tapered roller
Since it can be controlled using only spring force, it has advantages in terms of cost, reliability, durability, etc.

Therefore, there is an advantage that complicated control equipment such as a thrust force detection device, a pressure detection device, an electric control circuit, etc. is unnecessary.

If the sliding resistance changes, it will affect the accuracy of the roller expansion pressure, so it is necessary to always ensure the accuracy of each sliding part, but this can be reliably achieved, producing an excellent effect.

Therefore, the effect of increasing the reliability of the obtained product is achieved.

Therefore, in the taper processing device of this invention, regardless of the position of the front end of the shaft of the device,
When the mandrel is pushed forward by the thrust load of the elastic spring for thrust force control, and the inner diameter of a circular hole such as a pin hole is small, the expansion amount of the taper roller is small, and when it is large, the expansion amount is large. Therefore, as described above, an excellent effect is achieved in that accurate conical burnishing can be performed without measuring the inner diameter of the circular hole every time.

Therefore, the excellent effect that conical burnishing processing is always performed within a certain precision range is achieved without requiring any skill in operation.

Also, due to the design, while one circular hole is being tapered, the guide fitting is always fitted into the other circular hole, so both of the formed taper parts automatically become concentric and become out of alignment. This provides an excellent effect in that the conical burnishing process is formed accurately as designed.

[Brief explanation of the drawing]

Figures 1 to 4 are explanatory diagrams of one embodiment of this invention, in which Figure 1 is a schematic vertical cross-sectional view of the whole, Figure 2 is a cross-sectional view of the tapered roller associating with the work, and Figure 3 is a partial cross-sectional side view of the same. , Fig. 4 is a sectional view of the taper roller and the exit edge of the circular hole in the same taper processing process, Fig. 5 is a sectional view of the positional relationship of the pin hole of the piston, and Fig. 6 is an enlarged sectional view of part A in Fig. 5. Fig. 7 is a partial vertical sectional view of a taper processing tool based on the prior art, Fig. 8 is a - sectional view of Fig. 7, Fig. 9 is a partial sectional view of the taper processing process from one side, and Fig. 10 is FIG. 11 is a partial cross-sectional view of the taper process from both sides, and a cross-sectional view of each positional relationship during the taper process. DESCRIPTION OF SYMBOLS 1... Workpiece, 2... Circular hole, 6... Taper roller, 7... Slit, 5... Holding cylinder, 8... Taper part, 9... Mandrel, 16... Taper processing device, 27... Shaft, 30... Resilience spring, 29... Rod, 28... Rod stopper, 26... Shaft stopper, 20... Holder, 21... Insertion hole, 34... Other elasticity spring.

Claims (1)

[Scope of utility model registration request] A plurality of tapered rollers of the same size are slidably fitted into one of a pair of circular holes formed concentrically in the workpiece, and a plurality of tapered rollers of the same size are provided in an annular shape in the circumferential direction and parallel to the axis of the circular hole. Taper machining in which a holding cylinder is held via a corresponding slit so as to be movable in the radial direction and is slidable within the holding cylinder, and is equipped with a mandrel having a tapered portion at its tip that engages each tapered roller from the inside. In the apparatus, the holding tube has a guide fitting fitted into the other circular hole at its tip, which is integrally fixed with a tapered part formed therein, and the proximal end of the mandrel is driven. A stopper of the rod is slidably mounted on the tip of the shaft of the device and is biased in the insertion direction of the circular hole via an elastic spring for controlling thrust force against the mandrel, and integrally extends from the base end. is engaged with and disengaged from the stopper of the shaft, while the holding cylinder is engaged with and disengaged from the insertion hole of the workpiece holder via another elastic spring provided between the drive device and the circular hole side. A taper processing device characterized in that the taper processing device is press-biased.