First, the main types of drilling fixture
Drill jig is short for drill jig, which is mainly used to process holes and threads. It mainly consists of a drill sleeve, a drill template and a clamp body of a positioning and clamping device. Its main types are as follows.
(1) Fixing fixture is in use. This fixture has a fixed position on the machine tool and high machining accuracy. It is mainly used to process large diameter single hole on vertical drilling machine or parallel hole system on rocker drilling machine.
(2) Rotary jig This jig has an indexing device, so it is possible to process several axial or radial holes distributed around the axis on the workpiece.
(3) The turnover fixture is mainly used for machining holes on different surfaces of small workpieces, and the aperture is less than F8 ~ F 10 mm ... which can reduce the installation times and improve the position accuracy of machining holes. Its structure is simple, and the jig is generally turned by hand, so the fixture and workpiece should be less than 10 kg.
(4) Flat drilling die This drilling die has no clamping body, and its positioning element and clamping device are directly installed on the drilling template. The drilling template is clamped on the workpiece, which is suitable for machining small holes on larger workpieces. Clamp, simple and light structure, easy to remove chips; However, it takes time to assemble and disassemble the fixture from the workpiece every time, so the mass of the fixture should generally not exceed 10 kg.
(5) Sliding jig Sliding jig is a universal adjustable fixture with lifting drilling template. This kind of fixture has the advantages of simple structure, convenient operation, quick action and short manufacturing cycle, and is widely used in production.
Second, the key points of fixture design
1. Short drill
The drill sleeve is installed on the drilling template or fixture body, which is used to determine the position of the machining hole on the workpiece, guide the machining of the tool, improve the rigidity of the process system in the machining process and prevent vibration. Drill sleeves can be divided into standard drill sleeves and special drill sleeves.
(1) Fix the drill sleeve
(2) replaceable drill sleeve
(3) quickly replace the drill sleeve
(4) Special drill sleeve
2. Drilling template
The drilling template is used to install the drilling sleeve to ensure the correct position of the drilling sleeve on the drilling template. The drilling template is usually installed on the fixture body or bracket.
Common drilling templates are:
(1) Fixed drilling template
(2) Hinged drilling template
(3) Detachable (separated) drilling template
(4) hanging the drilling template
(2) Design features of boring machine fixture
Boring machine fixture, also known as boring die, is mainly used to process precision holes and hole systems on box or bearing parts. It is mainly composed of boring die holder, bracket, boring sleeve, boring bar and necessary positioning and clamping device. According to the arrangement of guide brackets, the types of boring machine fixtures are divided into double-support boring dies, single-support boring dies and unsupported boring dies.
Typical structure of boring machine fixture
(1) Front and rear double support boring dies
(2) Unsupported boring machine fixture
Second, the design points of boring machine fixture
1. Guide mode and guide bracket
The guiding mode of boring bar is divided into single support guiding and double support guiding. With single support, the boring bar is rigidly connected with the spindle of the machine tool, and the rotation accuracy of the spindle affects the boring accuracy, which is suitable for machining small holes and short holes. Double support, boring bar and machine tool spindle adopt floating connection. The position accuracy of boring depends on the position accuracy of the two guide holes of the boring die, and has nothing to do with the spindle accuracy of the machine tool. Boring die guide bracket is mainly used to install boring sleeve and bear cutting force. Because it requires sufficient rigidity and stability, it is generally necessary to have a large installation foundation and necessary reinforcing ribs in the structure; Moreover, it is not allowed to install a clamping mechanism on the bracket to bear the clamping reaction force, so as to avoid the deformation of the bracket and destroy the accuracy.
2. Drilling sleeve
The structure and accuracy of the boring sleeve directly affect the accuracy of the machined hole. Commonly used boring sleeves are:
(1) The fixed boring sleeve has the advantages of small overall size, simple structure and high guiding accuracy. However, the boring bar rotates and moves axially in the boring sleeve, and the boring sleeve is easy to wear, which is only suitable for low-speed boring.
(2) The rotary boring sleeve rotates with the boring bar, and there is only relative movement between the rotary boring sleeve and the boring bar, but there is no relative rotation. This kind of boring sleeve greatly reduces wear and will not be "stuck" due to friction and heating. So it is suitable for high-speed boring.
3. Drill pipes and floating joints
Boring rod is an important part of boring die. The diameter d and length of boring bar are mainly determined according to the drilling diameter d and the tool section size B×B (see table 1 1. 1). The diameter d of boring bar should be as large as possible, and the L/D of its double guide part should be ≤ 10. The l/d of the protruding part is less than 4 ~ 5, so that it has enough rigidity to ensure the machining accuracy. There are two kinds of boring bar lead-in structures of fixed boring sleeve: integral type and strip type. When boring, the boring rod and the spindle of the machine tool are connected in a floating way through the floating joint.
Fixture design of rotary drilling rig (as shown above)
Analysis of machining requirements for drilling () 6H9 holes in parts The machined surfaces before this process are:
(1)()40H7 hole and two end faces.
(2) Outer diameter () 90g6 two end faces.
The machine tool used in this process is Z5 125 vertical drilling machine. The cutter is a general standard cutter.
Second, determine the fixture type
The three holes (() 6H9) machined by this process are evenly distributed on the circumference of the working outer diameter () 90g6, which has the characteristics of small aperture, light workpiece weight, overall size and productivity. , so the rotary drilling jig is adopted.
(3) Draw up the positioning scheme and select the positioning elements.
(1) Positioning Scheme According to the structural characteristics of the workpiece, there are two positioning schemes:
1) Take () 40H7 hole and end face B as the locating surface, and one side of the split washer as the anti-rotation locating surface, and limit 6 degrees of freedom. This positioning scheme has datum misalignment error, which will cause large positioning error.
2) With the hole () 40H7 and the end face C as the locating surfaces, there is no datum misalignment error, so b = 0.
Comparing the above two positioning schemes, the second scheme is preliminarily determined.
Drawings can't be sent; These hopes will help you.