Adaptive offset dual pinhole positioning fixture

Abstract

This utility model provides an adaptive deviation double-pin hole positioning fixture, relating to the field of machine tool fixtures. It includes a base, a first base plate, a second base plate, a vertical moving mechanism, and a pre-positioning pin. The base has a receiving cavity. The vertical moving mechanism is fixed within the receiving cavity. The first base plate is fixed to the base. A positioning hole is vertically formed on the first base plate. The receiving cavity opening of the base is directly below the positioning hole. The vertical moving mechanism includes a telescopic end that can move vertically. The telescopic end extends upward from the positioning hole. A tightening sleeve is fixed to the upper side of the telescopic end. The tightening sleeve is cylindrical, and its cylindrical axis is vertical. The second base plate is fixed to the base. The pre-positioning pin is fixed to the second base plate, and its shaft is vertical. This adaptive deviation double-pin hole positioning fixture solves the problem in the prior art where a large tolerance in the spacing between the double pin holes reduces positioning accuracy, thus reducing the impact of the double-pin hole spacing tolerance on positioning accuracy.

Description

Technical Field

[0001] This utility model relates to the field of machine tool fixtures, and in particular to a double pin hole positioning fixture with adaptive deviation. Background Technology

[0002] Double pin positioning means that the workpiece to be processed has two pin holes, and the fixture has two pin shafts. The two pin shafts pass through the two pin holes of the workpiece to be processed and position it.

[0003] However, traditional double-pin positioning typically uses a cylindrical pin and a diamond pin for positioning. The positioning accuracy of double-pin positioning is limited by the spacing deviation between the two pin holes. When the pin hole and spacing tolerances are large, the positioning accuracy will be significantly reduced.

[0004] In the prior art, such as the double-pin positioning mechanism disclosed in Chinese Patent Application No. 201110285994.2, the structure and working principle of double-pin positioning are disclosed. Although its fixed pin and movable pin have a frustum-shaped shape with a small upper diameter and a large lower diameter, the frustum shape can only improve the tolerance of insertion into the two holes of the part. When there is a deviation in the distance or diameter of the two pin holes of the workpiece, because the upper diameter of the pin is small, the workpiece can first be inserted obliquely into the upper end of the pin and then slowly lowered. However, after insertion, there will be a gap between the workpiece and the pin, resulting in poor positioning accuracy. Utility Model Content

[0005] To address the aforementioned technical problems, the adaptive deviation double pin hole positioning fixture provided by this utility model can reduce the impact of the double pin hole spacing tolerance on positioning accuracy.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: The adaptive deviation double-pin hole positioning fixture provided by this utility model includes a base, a first base plate, a second base plate, a vertical moving mechanism, and a pre-positioning pin. The base has a receiving cavity. The vertical moving mechanism is fixed within the receiving cavity. The first base plate is fixed to the base. The first base plate has a positioning hole in the vertical direction. The opening of the receiving cavity of the base is directly below the positioning hole. The vertical moving mechanism includes a telescopic end that can move vertically. The telescopic end extends upward from the positioning hole. A tightening sleeve is fixed to the upper side of the telescopic end. The tightening sleeve is cylindrical, and its cylindrical axis is vertical. The second base plate is fixed to the base. The pre-positioning pin is fixed to the second base plate, and its shaft is vertical.

[0007] The adaptive deviation double pin hole positioning fixture provided by this utility model preferably further includes a pad; the pad is fixed on the upper side of the first substrate.

[0008] The adaptive deviation double-pin hole positioning fixture provided by this utility model preferably includes a telescopic end comprising a first cylindrical segment and a second cylindrical segment; the second cylindrical segment is coaxially disposed on the upper side of the first cylindrical segment; the diameter of the second cylindrical segment is smaller than the diameter of the first cylindrical segment; a cylindrical expansion through hole is vertically formed on the upper cylindrical side of the expansion sleeve; a plurality of strip-shaped deformation holes are formed in the expansion through hole outward from the center; a cylindrical fixing hole is formed on the lower cylindrical side of the expansion sleeve; the cylindrical diameter of the expansion through hole is larger than the diameter of the first cylindrical segment; the second cylindrical segment is inserted into the fixing hole with an interference fit; the first cylindrical segment extends out from the expansion through hole.

[0009] The adaptive deviation double pin hole positioning fixture provided by this utility model preferably has a plurality of strip-shaped adaptive deformation holes that diffuse outward from the center of the fixing hole; all the strip-shaped deformation holes are arranged in a circumferential array at equal intervals along the cylindrical axis of the expansion sleeve; all the adaptive deformation holes are arranged in a circumferential array at equal intervals along the cylindrical axis of the expansion sleeve; the angle between the adaptive deformation hole and the two adjacent strip-shaped deformation holes is the same.

[0010] The adaptive deviation double pin hole positioning fixture provided by this utility model preferably has a chamfered edge on the bottom edge of the cylindrical prepositioning pin.

[0011] The above technical solution has the following advantages or beneficial effects: This utility model provides an adaptive deviation double-pin hole positioning fixture, relating to the field of machine tool fixtures. It includes a base, a first base plate, a second base plate, a vertical moving mechanism, and a pre-positioning pin. The base has a receiving cavity. The vertical moving mechanism is fixed within the receiving cavity. The first base plate is fixed to the base. The first base plate has a positioning hole in a vertical direction. The opening of the receiving cavity of the base is directly below the positioning hole. The vertical moving mechanism includes a telescopic end that can move vertically. The telescopic end extends upward from the positioning hole. A tightening sleeve is fixed to the upper side of the telescopic end. The tightening sleeve is cylindrical, and its cylindrical axis is vertical. The second base plate is fixed to the base. The pre-positioning pin is fixed to the second base plate, and its shaft is vertical. This adaptive deviation double-pin hole positioning fixture solves the problem in the prior art where a large tolerance in the spacing between the double pin holes reduces positioning accuracy, thus reducing the impact of the double-pin hole spacing tolerance on positioning accuracy. Attached Figure Description

[0012] The present invention, its features, shape, and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Like reference numerals denote like parts throughout the drawings. The drawings are not intentionally drawn to scale; the focus is on illustrating the gist of the invention.

[0013] Figure 1 This is a schematic diagram of the overall structure of the adaptive deviation double pin hole positioning fixture provided in Embodiment 1 of this utility model.

[0014] Figure 2 This is a schematic diagram of the expansion sleeve structure of the adaptive deviation double pin hole positioning fixture provided in Embodiment 1 of this utility model.

[0015] Figure 3 This is a schematic diagram of the adaptive deviation double pin hole positioning fixture provided in Embodiment 1 of this utility model when fixing the workpiece. Detailed Implementation

[0016] Example 1: The adaptive deviation double-pin hole positioning fixture provided in Embodiment 1 of this utility model, such as Figures 1 to 3 As shown, the system includes a base 1, a first substrate 2, a second substrate 3, a vertical moving mechanism 4, and a pre-positioning pin 5. The base 1 has a receiving cavity 11. The vertical moving mechanism 4 is fixed within the receiving cavity 11. The first substrate 2 is fixed to the base 1. The first substrate 2 has a vertically oriented positioning hole 21. The positioning hole 21 is directly below the opening of the receiving cavity 11 of the base 1. The vertical moving mechanism 4 includes a telescopic end 41 that can move vertically. The telescopic end 41 extends upward from the positioning hole 21. A tightening sleeve 6 is fixed to the upper side of the telescopic end 41. The tightening sleeve 6 is cylindrical, and its cylindrical axis is vertical. The second substrate 3 is fixed to the base 1. The pre-positioning pin 5 is fixed to the second substrate 3, and its shaft is vertical.

[0017] The adaptive deviation double pin hole positioning fixture provided in Embodiment 1 of this utility model is used to position the workpiece. The workpiece has two corresponding pin holes that match the pre-positioning pin 5 and the expansion sleeve 6 respectively. During positioning, one pin hole of the workpiece is first fitted into the pre-positioning pin 5 on the second base plate 3 (the upper end of the pre-positioning pin 5 is higher than the upper end of the expansion sleeve 6 in the initial state), and at the same time, the other pin hole of the workpiece is aligned with the expansion sleeve 6 above the first base plate 2, with the pin holes of the workpiece coaxially corresponding; then, the vertical moving mechanism 4 in the receiving cavity 11 of the base 1 is activated, and its telescopic end 41 moves upward in the vertical direction, extending upward from the positioning hole 21 of the first base plate 2, driving the expansion sleeve 6 fixed on the upper side of the telescopic end to move upward synchronously, so that the expansion sleeve 6 enters the corresponding pin hole of the workpiece. When the expansion sleeve moves with the telescopic end, it will expand radially, and the driving force of the vertical moving mechanism will make the expansion sleeve 6 fit tightly against the inner wall of the pin hole of the workpiece, ultimately achieving rigid fixation of the workpiece. Compared to existing technologies, when the tolerance between the two pin holes on the workpiece is large, it is difficult for the two pins of the fixture to be inserted into the two pin holes simultaneously. Even if the top of the pin is chamfered, after insertion, there will be a gap between the pin and the pin hole because the axis of the pin cannot be aligned with the axis of the pin hole, resulting in loose positioning. This embodiment utilizes the deformation function of the expansion sleeve 6 itself. Even if the cylindrical axis of the expansion sleeve 6 is offset from the axis of the workpiece pin hole, the outer wall of the expansion sleeve 6 can still deform towards its own cylindrical axis, thereby maintaining tight contact with the inner wall of the pin hole, thus enabling more stable positioning.

[0018] The adaptive deviation double pin hole positioning fixture provided in Embodiment 1 of this utility model solves the problem in the prior art that when the tolerance of the double pin hole spacing is large, the positioning accuracy will be reduced, and the influence of the double pin hole spacing tolerance on the positioning accuracy can be reduced.

[0019] In this embodiment, a pad 7 is also included; the pad 7 is fixed on the upper side of the first substrate 2. The pad 7 is fixed above the first substrate 2 and serves as the direct support surface for the workpiece. It is used to protect the first substrate 2 and prevent the first substrate 2 from being squeezed and deformed by the workpiece, thereby preventing the surface of the first substrate 2 from wearing down after long-term use, which would lead to a decrease in its flatness and affect the clamping of subsequent workpieces.

[0020] In this embodiment, the telescopic end 41 includes a first cylindrical section 411 and a second cylindrical section 412; the second cylindrical section 412 is coaxially disposed on the upper side of the first cylindrical section 411; the diameter of the second cylindrical section 412 is smaller than the diameter of the first cylindrical section 411; a cylindrical expansion through hole 61 is vertically opened on the upper cylindrical side of the expansion sleeve 6; a plurality of strip-shaped deformation holes 62 are opened in the expansion through hole 61 outward from the center; a cylindrical fixing hole 63 is opened on the lower cylindrical side of the expansion sleeve 6; the cylindrical diameter of the expansion through hole 61 is larger than the diameter of the first cylindrical section 411; the second cylindrical section 412 is inserted into the fixing hole 63 with an interference fit; the first cylindrical section 411 extends out from the expansion through hole 61. The lower fixing hole 63 of the expansion sleeve 6 is interference-fitted with the second cylindrical section 412 of the telescopic end to ensure that the vertical movement of the telescopic end 41 can be stably transmitted to the expansion sleeve 6, avoiding expansion failure due to loose connection. The diameter of the first cylindrical section 411 of the telescopic end is larger than that of the second cylindrical section 412. The strip-shaped deformation holes 62 around the expansion through hole 61 diffuse outward from the center, cutting the upper part of the expansion sleeve into several elastic petal-shaped structures. These groove-shaped holes provide radial deformation allowance for the expansion sleeve. When the telescopic end 41 moves vertically upward to insert the expansion sleeve 6 into the pin hole, the elastic petal-shaped structure of the upper part of the expansion sleeve can deform towards the second cylindrical section 412. The inner wall of the elastic petal-shaped structure is at the limit position of elastic deformation when it contacts the second cylindrical section 412, avoiding the plastic deformation of the expansion sleeve 6 from affecting the subsequent clamping operation.

[0021] In this embodiment, the fixing hole 63 is provided with a plurality of strip-shaped adaptive deformation holes 64 spreading outward from the center; all the strip-shaped deformation holes 62 are arranged in a circular array at equal intervals along the cylindrical axis of the expansion sleeve 6; all the adaptive deformation holes 64 are arranged in a circular array at equal intervals along the cylindrical axis of the expansion sleeve 6; the angle between the adaptive deformation hole 64 and the two adjacent strip-shaped deformation holes 62 is the same. The deformation-adaptive holes 64 provided around the fixing hole 63 also cause the lower end of the expansion sleeve 6 to form multiple elastic petal structures. When the elastic petal structure on the upper side of the expansion sleeve 6 deforms, the elastic petal structure on the lower side of the expansion sleeve 6 can reduce the stress caused by the deformation on the upper side of the expansion sleeve 6 through deformation. Since the spacing tolerance between the two pin holes may have positive and negative deviations, all the strip deformation holes 62 in this embodiment are arranged in a circular array with equal spacing along the axis, and the elastic petal structures on the upper part of the expansion sleeve 6 are evenly distributed. When the first cylindrical section 411 pushes upward, the expansion amount of each elastic petal structure is consistent, so as to adapt to the situation where the spacing tolerance between the two pin holes is too large or too small. The purpose of having the same angle between the deformation-adaptive hole 64 and the two adjacent strip deformation holes 62 is to make the deformation of the elastic petal structures in the upper and lower parts staggered, so as to avoid the appearance of a weak area in the vertical direction due to the alignment of the strip deformation holes 62 and the deformation-adaptive hole 64.

[0022] In this embodiment, the bottom edge of the cylindrical upper surface of the expansion sleeve 6 is chamfered; the bottom edge of the cylindrical upper surface of the prepositioning pin 5 is also chamfered. The chamfer will form an inclined guiding surface on the upper edge of the prepositioning pin 5 and the expansion sleeve 6. When there is a slight deviation in the central axis of the workpiece pin hole, the edge of the workpiece pin hole will first contact the inclined surface of the chamfer, and the position will be automatically corrected by the guiding effect of the inclined surface.

[0023] In summary, this utility model provides an adaptive deviation double-pin hole positioning fixture, relating to the field of machine tool fixtures. It includes a base, a first base plate, a second base plate, a vertical moving mechanism, and a pre-positioning pin. The base has a receiving cavity. The vertical moving mechanism is fixed within the receiving cavity. The first base plate is fixed to the base. The first base plate has a positioning hole in the vertical direction. The opening of the receiving cavity of the base is directly below the positioning hole. The vertical moving mechanism includes a telescopic end that can move vertically. The telescopic end extends upward from the positioning hole. A tightening sleeve is fixed to the upper side of the telescopic end. The tightening sleeve is cylindrical, and its cylindrical axis is vertical. The second base plate is fixed to the base. The pre-positioning pin is fixed to the second base plate, and its shaft is vertical. The adaptive deviation double-pin hole positioning fixture provided by this utility model solves the problem in the prior art where a large tolerance in the spacing between the double pin holes reduces positioning accuracy, thus reducing the impact of the double-pin hole spacing tolerance on positioning accuracy.

[0024] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the contents of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. A self-adapting offset dual pin-hole positioning fixture, characterized in that, It includes a base, a first substrate, a second substrate, a vertical moving mechanism, and a pre-positioning pin; The base is provided with a receiving cavity; the vertical moving mechanism is fixed in the receiving cavity; The first substrate is fixed on the base; the first substrate has a positioning hole in the vertical direction; the positioning hole is directly below the receiving cavity opening of the base; the vertical moving mechanism includes a telescopic end that can move vertically; the telescopic end extends upward from the positioning hole; a tightening sleeve is fixed on the upper side of the telescopic end; the tightening sleeve is cylindrical; the cylindrical axis of the tightening sleeve is vertical. The second substrate is fixed on the base; the prepositioning pin is fixed on the second substrate; the prepositioning pin shaft is vertical.

2. The self-adapting offset dual pin bore fixture of claim 1, wherein, It also includes a pad; the pad is fixed to the upper side of the first substrate.

3. The adaptive deviation double-pin hole positioning fixture as described in claim 2, characterized in that, The telescopic end includes a first cylindrical segment and a second cylindrical segment; the second cylindrical segment is coaxially disposed on the upper side of the first cylindrical segment; the diameter of the second cylindrical segment is smaller than the diameter of the first cylindrical segment; The expansion sleeve has a cylindrical expansion hole vertically opened on the upper side of the cylinder; the expansion hole has a number of strip-shaped deformation holes that spread outward from the center. The lower cylindrical side of the expansion sleeve is provided with a cylindrical fixing hole; The diameter of the expansion hole is larger than the diameter of the first cylindrical segment; The second cylindrical section is inserted into the fixing hole with an interference fit; The first cylindrical section extends out from the expansion through hole.

4. The adaptive deviation double-pin hole positioning fixture as described in claim 3, characterized in that, The fixing hole is provided with a number of strip-shaped deformation-adaptive holes that spread outward from the center; All of the strip-shaped deformation holes are arranged in a circumferential array at equal intervals along the cylindrical axis of the expansion sleeve; All of the aforementioned adaptive deformation holes are arranged in a circumferential array at equal intervals along the cylindrical axis of the expansion sleeve; The angles between the adaptive deformation holes and the two adjacent strip deformation holes are the same.

5. The self-adapting offset dual pin bore fixture of claim 3, wherein, The bottom edge of the cylindrical expansion sleeve is chamfered.

6. The self-adapting offset dual pin bore fixture of claim 1, wherein, The bottom edge of the cylindrical prepositioning pin is chamfered.

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