CN107695727B

CN107695727B - Universal clamp for structural parts and use method thereof

Info

Publication number: CN107695727B
Application number: CN201711070507.4A
Authority: CN
Inventors: 刘文进
Original assignee: Xian Aerospace Precision Electromechanical Institute
Current assignee: Xian Aerospace Precision Electromechanical Institute
Priority date: 2017-11-03
Filing date: 2017-11-03
Publication date: 2019-12-17
Anticipated expiration: 2037-11-03
Also published as: CN107695727A

Abstract

The invention relates to a universal fixture for structural parts and a using method thereof. The universal fixture comprises an upper body and a lower body which are fixedly connected; the upper body is a first cylinder with a notch in the middle, and a positioning pin hole is formed between the uppermost part of the notch of the first cylinder and the upper end face of the first cylinder; the lower body is a second cylinder, the connecting position of the first cylinder and the second cylinder is processed into a circular arc-shaped large chamfer, and the connecting position of the notch and the first cylinder is also processed into a circular arc-shaped large chamfer. By using the universal fixture disclosed by the invention and matching with a processing machine tool, clamping and positioning of different types of structural parts can be realized, and the clamping and positioning speed is high and the precision is high.

Description

universal clamp for structural parts and use method thereof

Technical Field

the invention belongs to the technical field of machining, and particularly relates to a universal clamp for a structural part and a using method of the universal clamp.

background

at present, in the development and production of structural parts, a special fixture is designed to reduce the complex process of clamping workpieces and the time for alignment and tool setting, so that the processing process is simple, and meanwhile, in order to ensure the processing precision and the processing efficiency of the parts or solve the problem of the safety height of the bottom surface of multi-axis equipment and a machine tool, the special fixture is almost required to be manufactured for processing each part (such as a five-axis equipment processing hexahedral part and preferably five surfaces to be mounted and processed at one time) which needs to be positioned by a positioning hole or needs to be fully exposed in the processing process on the multi-axis equipment, so that the development and production period is prolonged, meanwhile, a large amount of special fixtures are manufactured, so that the material waste is caused, 1-2 parts of some types of products are not produced, and the special fixture is used for replacing similar parts or only can be used for waste treatment.

Based on the non-universality of the special clamp, a combined clamp is also used at present, and the assembly of the combined clamp is the whole process of assembling the combined clamp elements into the clamp required by a machined part according to certain steps and requirements. The method is generally divided into the steps of preparation, planning of an assembly scheme, trial assembly, connection and adjustment of fastening elements, inspection and the like, so that the assembly is complex and difficult by adopting the combined clamp, and the rigidity of the combined clamp in the use process cannot meet the preset requirement.

the special clamp for the existing part structure parts comprises the following parts:

As shown in fig. 1, a special fixture for mounting positioning hole irregularities, a special fixture for four-point supporting and positioning shown in fig. 2, a special fixture for three-point supporting and positioning shown in fig. 3, and a special fixture for mounting a screw in a five-axis device, which are shown in fig. 4, are required to be mounted once to finish five-surface processing, the special fixtures for mounting the screw are required to be mounted from bottom to top, and the conventional special fixtures have the following problems:

1. The manufacturing period of the clamp is long, and once the production of the part is stopped, the special clamp is basically scrapped;

2. the production period of the developed product is prolonged;

3. The clamp alignment is slow, and the central coordinate system of the clamp cannot be quickly determined;

4. resulting in waste of the jig material.

in addition, the conventional modular fixture has a fixture body as a base member for connecting all the components of the fixture together (the fixture body of the modular fixture shown in fig. 5). If auxiliary elements such as a positioning piece, a screw, a pressing plate, a supporting piece, a tool setting guide device, a connecting piece and the like are needed to finish the structure part clamp, the shape similar to that shown in the attached drawings 1-4 is finished through assembly, but the problems are obvious:

1. the rigidity of the combined clamp is poor;

2. the element reserve is large;

3. The combination precision is easy to change;

4. the structure is not compact;

5. assembly is time consuming.

disclosure of Invention

in order to solve the problems in the background art, the invention provides a universal fixture which is universal for various structural parts and has high clamping speed and high positioning precision and a use method thereof.

the specific technical scheme of the invention is as follows:

the invention provides a universal fixture for structural parts, which comprises an upper body and a lower body which are fixedly connected;

The upper body is a first cylinder with a notch in the middle, and a positioning pin hole is formed between the uppermost part of the notch of the first cylinder and the upper end face of the first cylinder;

the lower body is a second cylinder, the connecting position of the first cylinder and the second cylinder is processed into a circular arc-shaped large chamfer, and the connecting position of the notch and the first cylinder is also processed into a circular arc-shaped large chamfer.

furthermore, in order to prevent the orifice of the locating pin hole from deforming due to frequent contact between the center of the machine tool and the locating pin hole in the universal fixture, one end, close to the upper end face of the first cylinder, of the locating pin hole is provided with an excessive taper hole matched with the taper of the center of the machine tool, and meanwhile, in order to prevent a pin from being inserted into the locating pin hole normally, an 18-degree transition hole is additionally arranged between the excessive taper hole and the locating pin hole; specifically, the taper of the over taper hole is 60 °.

Furthermore, a clearance groove is formed in the lower end face of the second column body.

Specifically, the first cylinder and the second cylinder are both circular cylinders.

in order to facilitate production and manufacture, the upper body and the lower body are manufactured in an integrated forming mode.

based on the above description of the structure of the universal fixture, a method for using the universal fixture is described, which specifically includes the following steps:

1) determining that the number of the positioning holes of the structural part to be machined is N, measuring coordinate values of N positioning holes in the structural part to be machined, and inputting the coordinate values into a control system of a machining tool;

2) preparing general type clamps with the same quantity according to the N quantity of the positioning holes confirmed in the step 1);

3) positioning a structural part to be processed;

placing a first universal fixture under the center of a working platform of a processing machine tool, manually controlling the center of the processing machine tool to approach the universal fixture, and manually adjusting the position of the universal fixture to enable the center of the processing machine tool to be coaxial with a transition taper hole of the universal fixture and tightly prop the universal fixture on the working platform of the processing machine tool;

4) fixing the structural parts to be processed;

fixing a first universal fixture on a working platform of a machining bed by utilizing a pressing plate or a clearance groove;

5) According to the coordinate values of N positioning holes of the structural part to be processed, which are input into the control system of the processing machine tool in advance in the step 1), repeating the step 3) and the step 4), and sequentially and fixedly mounting the rest universal fixtures on the working platform of the processing machine tool;

6) the structure part to be processed and the universal fixtures are respectively and fixedly connected through the positioning screws, so that the structure part to be processed is clamped.

When the required machining precision of the part to be machined is higher:

The step 5) is specifically as follows:

5.1) according to the coordinate values of N positioning holes of the structural part to be processed, which are input into a control system of the processing machine tool in advance in the step 1), repeating the step 3) and the step 4), sequentially and fixedly mounting other N-2 universal fixtures on a working platform of the processing machine tool, reserving one universal fixture, and only performing the step 3) without performing the step 4);

5.2) placing the structural part to be processed on the N universal fixtures, and inserting the structural part to be processed into a positioning hole of one fixed universal fixture and a positioning hole of an unfixed universal fixture from the structural part to be processed respectively by using pins;

5.3) taking the pin in the positioning hole of the universal fixture fixed in the step 5.2) as a rotating shaft, taking the whole of the to-be-machined structural part and the unfixed universal fixture as a rotating body, correcting the machining reference edge of the to-be-machined structural part by using a dial indicator, adjusting the angular orientation of the to-be-machined structural part and the unfixed universal fixture to meet the precision requirement, and then fixing the universal fixture on a working platform of a machining lathe by using a pressing plate or a cutter blank groove; thereby completing the fixing of the N universal clamps.

the invention has the advantages that:

1. In order to adapt to production and processing of most structural parts, the clamp is designed to be composed of 3-4 cylinders, the zero position of the central coordinate system of the clamp can be set in the machine tool coordinate system according to the requirements of the shape and the size of the part in the using process, then the placing position of the cylinders is determined, and then the positions of the cylinder mounting holes are directly positioned by utilizing the machine tool coordinate system according to the positions of the part mounting positioning holes. The special fixture for single parts is replaced, and the fixture is suitable for most structural parts.

2. The universal fixture can replace most special fixtures for use, step pins can be taken out from the lower portion of the fixture conveniently (when pin holes of the fixture are larger than pin mounting positioning holes of parts), or the positioning holes are blind holes and five-axis equipment, parts for completing five-surface machining need to be clamped once, the parts comprise parts for additionally arranging process mounting positioning holes, parts for fixedly mounting screws from bottom to top and the like, and hollow parts of a fixture cylinder are particularly increased.

3. in order to solve the problems of strength, rigidity, precision and the like of the universal clamp, a single column of the clamp is subjected to thinning processing. The universal fixture has the advantages that the diameter of the lower end of the universal fixture is larger, the corners are excessive due to the use of large arcs, and the cutter grooves are reserved on the bottom surface.

4. in order to prevent the phi 14 pin hole orifice from deforming due to the fact that the machine tool center is frequently contacted with a 60-degree center hole in a universal fixture, and a pin cannot be normally inserted, an 18-degree transition taper hole is specially added.

5. for parts with higher requirements on the precision of the clamp, the universal clamp is used for positioning a plurality of universal clamps, then the dial indicator is used for aligning the reference edge of the structural part to be machined, and after the angular direction of the structural part to be machined meets the precision requirement, all the clamps and the structural parts to be machined are fixed, so that the precision of the whole clamp is ensured, and the positioning precision can reach 0.005 mm.

drawings

FIG. 1 illustrates a conventional special fixture for mounting irregular positioning holes;

FIG. 2 is a diagram of a conventional special fixture for four-corner support positioning;

FIG. 3 is a prior art special fixture for three-point support positioning;

fig. 4 shows a conventional special clamp for installing a screw from bottom to top.

FIG. 5 is a view showing a structure of a conventional modular fixture;

FIG. 6 is a block diagram of the universal fixture of the present invention;

FIG. 7 is a cross-sectional view of FIG. 6;

FIG. 8 is an enlarged view of a portion of FIG. 7;

FIG. 9 is a schematic view of a universal fixture mounting orientation;

FIG. 10 is a schematic view of the universal fixture and the structural component to be machined;

The reference numbers are as follows:

1-notch, 2-first column, 3-positioning pin hole, 4-second column, 5-arc large chamfer, 6-transition taper hole, 7-undercut groove and 8-transition hole.

Detailed Description

first, the structure of the universal type jig provided by the present invention will be described with reference to fig. 6 to 8:

The universal fixture comprises an upper body and a lower body which are fixedly connected;

the upper body is a first cylinder 2 with a gap 1 in the middle, and a positioning pin hole 3 is arranged between the uppermost part of the gap 1 of the first cylinder 2 and the upper end surface of the first cylinder 2;

The lower body is a second cylinder 4, the connecting position of the first cylinder 2 and the second cylinder 4 is processed into an arc-shaped large guide angle 5, and the connecting position of the notch 1 and the first cylinder 2 is also processed into the arc-shaped large guide angle 5 (the arc-shaped large chamfer angle is arranged here to ensure the attractive and elegant appearance of the clamp on the premise of ensuring the rigidity of the clamp). Further, the first cylinder and the second cylinder are both circular cylinders.

in order to install and position the positioning pin simply and quickly, one end of the positioning pin hole 3 close to the upper end face of the first cylinder 2 is provided with an excessive taper hole 6 matched with the taper of the tip of the processing machine tool, and specifically, the taper of the excessive taper hole 6 is 60 degrees.

in order to prevent the deformation of the hole opening of the positioning pin hole caused by the frequent contact of the machine tool center and the positioning pin hole on the universal fixture and prevent the normal insertion of the pin, a transition hole 8 for preventing the deformation of the hole opening of the pin is arranged between the positioning pin hole 3 and the excessive taper hole 6.

in order to facilitate the installation of the universal fixture on a working platform of a processing machine tool, a clearance groove 7 is formed in the lower end surface of the second column body 4.

In order to facilitate processing and manufacturing and save materials, the upper body and the lower body of the universal fixture are manufactured in an integrated forming mode.

in light of the above description of the universal fixture, how the universal fixture is used in conjunction with a processing machine to achieve positioning of structural parts will now be described with a specific embodiment:

1) Supposing that four mounting holes are arranged on the structural part to be processed, the coordinate size of each mounting positioning hole is as follows: the point A (98, 98), the point B (-98, 98), the point C (-98 ) and the point D (98, -98) input the four coordinate values into a control system of the processing machine tool;

2) Preparing 4 universal type clamps; wherein: the A point corresponds to the A universal fixture, the B point corresponds to the B universal fixture, the C point corresponds to the C universal fixture, and the D point corresponds to the D universal fixture;

3) Positioning a structural part to be processed;

Placing a No. A universal fixture under the center of a working platform of a processing machine tool, manually controlling the center of the processing machine tool to approach the No. A universal fixture, and manually adjusting the position of the No. A universal fixture to enable the center of the processing machine tool to be coaxial with a transition taper hole of the No. A universal fixture and tightly prop the universal fixture on the working platform of the processing machine tool;

4) fixing the structural parts to be processed;

fixing the No. A universal fixture on a working platform of a processing machine tool by utilizing a pressing plate or a clearance groove;

5) According to the coordinate values of N positioning holes of the structural part to be processed, which are input into the control system of the processing machine tool in advance in the step 1), repeating the step 3) and the step 4), and sequentially and respectively fixedly mounting the No. B, C, D universal fixture on the working platform of the processing machine tool;

6) the structure part to be processed and the 4 universal clamps are respectively and fixedly connected through the positioning screws, so that the structure part to be processed is clamped.

in order to meet the requirement of higher positioning accuracy, the positioning method of the invention also makes the following optimized scheme, as shown in figures 9-10,

according to the requirements of the steps, firstly, the steps 1-4 are carried out on the general fixture A,

5.1) according to the coordinate values of 4 installation positioning holes of the structural part to be processed which is input into the control system of the processing machine tool in advance in the step 1), repeating the step 3) and the step 4) to fixedly install the No. B universal fixture and the No. C universal fixture on the working platform of the processing machine tool in sequence, reserving the No. 4 universal fixture and only carrying out the step 3), not carrying out the step 4)

5.2) placing the structural parts to be processed on 4 universal fixtures, and inserting the structural parts to be processed into the positioning holes of the universal fixture B and the universal fixture D respectively by using pins;

5.3) taking the pin in the positioning hole of the universal fixture B in the step 5.2) as a rotating shaft, taking the whole of the structural part to be processed and the universal fixture D as a rotating body, correcting the processing reference edge of the structural part to be processed by using a dial indicator, adjusting the angular directions of the structural part to be processed and the universal fixture D to meet the precision requirement, and then fixing the universal fixture D on a working platform of a processing and machining machine by adopting a pressing plate or a clearance groove; thus completing the fixing of 4 universal-type clamps.

and (3) pulling out pins on the universal fixture B and the universal fixture D, and tightening the pin screws on the 4 mounting positioning holes of the structural part to be processed and the positioning pin holes of the 4 universal fixtures again to complete the clamping and positioning of the part. The two pins and the supporting surface of the universal fixture position X, Y-axis two degrees of freedom of movement and rotation of the part and Z-axis degree of freedom of rotation, and the clamping screw limits the Z-axis degree of freedom of movement of the part, so far, 6 degrees of freedom of the part are limited.

when the diameters of the positioning installation hole on the part and the positioning pin hole on the universal fixture are different, the part can be made into a step pin, the step pin needs to be pulled out before the screw is screwed, the step pin can be determined according to the size of the hole when the pin is pulled out, when the hole on the part is large, the part is pulled out from the direction of the part, and when the hole on the fixture is large, the part is pulled out from the lower part of the fixture.

Claims

1. The utility model provides a general type anchor clamps of structure class part which characterized in that:

comprises an upper body and a lower body which are integrally formed;

the lower body is a second cylinder, the connecting position of the first cylinder and the second cylinder is processed into an arc-shaped large chamfer, and the position where the gap is connected with the first cylinder is also processed into an arc-shaped large chamfer;

one end of the positioning pin hole close to the upper end face of the first cylinder is provided with a transition taper hole matched with the taper of the tip of the processing machine tool; the taper of the transition taper hole is 60 degrees;

And a transition hole with the taper of 18 degrees is also arranged between the transition taper hole and the positioning pin hole.

2. The universal fixture for structural parts as claimed in claim 1, wherein: the lower end surface of the second column body is provided with a clearance groove.

3. the universal fixture for structural parts as claimed in claim 2, wherein: the first cylinder and the second cylinder are both circular cylinders.

4. The use method of the universal fixture for the structural parts is characterized by comprising the following steps:

3) positioning a structural part to be processed;

4) Fixing the structural parts to be processed;

fixing a first universal fixture on a working platform of a processing machine tool by utilizing a pressing plate or a clearance groove;

6) The structure part to be processed and the universal fixtures are respectively and fixedly connected through the positioning mounting holes and the screws, so that the structure part to be processed is clamped.

5. the use method of the universal fixture for the structural parts as claimed in claim 4, wherein the universal fixture comprises: when the required machining precision of the part to be machined is higher:

The step 5) is specifically as follows: