Abstract: The comb forming process of 10 small grooves on the axle parts of V30 door opener is discussed. The forming knife is designed. The cutting parameters and cutting amount are calculated. The durability of the tool is discussed. The working effect is good through workshop.

Figure 1 Parts sketch

The V30 door opener axle is a key component on the elevator door opener. The material is LC4 and the shape of the part is shown in Figure 1. In order to ensure the accuracy of 10 small grooves in the part, the author designed and manufactured the DS/1006 comb forming knife.

1 Material structure and geometric parameters of the tool

1. material

The material used for the V30 door opener axle is super-hard aluminum alloy LC4 with a hardness of 150HB<8HRC (177HB is equivalent to 8HRC). There are 10 small grooves to be machined on the outer circumference of the workpiece, which has high processing precision, complex shape and long knife width. In view of the material hardness and shape characteristics of the workpiece, we chose W18Cr4V high speed steel.
2. 1.2 Tool structure

Forming turning tools can be divided into two types: flat (flat) and round: round forming knives have a longer life than sheet-shaped (flat) forming knives. This forming knife has a complicated manufacturing process and high cost. To this end, we have chosen a sheet-shaped (flat-body) forming knife, which consists of a blade-shaped blade and a knife bar. The tool bar and the blade are separated, the blade is interchangeable, and the tool bar can be reused. The blade machining only needs to process the upper and lower corners, and the tool rake angle is naturally formed during installation. The tool manufacturing process is good, the cycle is short, and the low cost is the biggest feature of this type of forming knife. The DS/1006 comb forming knife is a flat-shaped structure (Fig. 2). The tool structure is the mode of the machine clamp. The blade is a 10-toothed comb structure. There is also a positioning surface in front of the 10 teeth to ensure 1.8mm from the center line to the end of the first tooth on the workpiece. This ensures quality and is easy to use. The positioning surface of the arbor requires a roughness of Ra0.8μm. It is used to adjust the edge of the comb knives parallel to the axis of the workpiece during tool installation to ensure that the shape of the 10 small grooves of the workpiece is correct and the depth is consistent.


Figure 2 Tool sketch

3. Geometric angle selection
1. The rake angle of the forming tool g ₀ is usually a small value to ensure the shape, but a large rake angle can be used when processing aluminum. Taking into account various factors and data of relevant data, the front angle of the DS/1006 forming turning tool is 8°. The forward angles of the blades are not equal, and the forward angle is from 8° to 0° and from 0° to 8°.
2. The shape of the back angle a ₀ forming turning tool is complicated, the back angle is generally taken to a small value, and the processed aluminum material can be used with a larger back angle. Considering various factors, the back angle of the forming blade is determined to be a ₀ = 10°. The normal relief angles around the blade are also unequal, with the normal relief angle from 10° to 0° and from 0° to 10°.

2 Calculation of cutting force

1. Expanded length of the machined surface
The unfolded length of the machined surface (Fig. 3)
It is known that the tooth top fillet R = 0.4 mm, r = 0.2 mm, the tooth angle is 40 °, and the tooth pitch is 2.34 mm. Calculated by ΔABC
In the quadrilateral AEOE'
In the quadrilateral BF'O'F
One slot length
10 slots are: 50.1mm
It can be seen that the calculated processing expansion length is 50.1mm.
2. The relevant information on cutting force calculation: "Aluminum alloy has good cutting performance, cutting force is much smaller than when cutting brass and steel. When the cutting amount is the same, the force and energy consumption of the tool is better than cutting brass and steel. Correspondingly low." According to the cutting force formula
   

   Figure 3 trough size

   F _z =C _Fz a ^{x _Fz} pf ^{y _Fz} v ^{n _Fz} k _{F z} formula C _{F z} =490, x _{F z} =1, y _{F z} =1, n _{F z} =0
   When the forming turning tool width is ≥50mm and the feed amount is f=0.025～0.055mm/r, the feed amount can be substituted into the above formula. F _z = 490 × 50.11 ¹ × 0.025 ¹ × 1 × k _{F z} = 614k _{F z}
   F _z = 490 × 50.11 ¹ × 0.055 ¹ × 1 × k _{F z} =1350k _{F z}
   k _{F z} is the correction factor of the cutting force, which is determined by the mechanical properties of the material to be processed, the rake angle, the lead angle, and the radius of the tool nose. The empirical formula for the cutting force when machining steel is: F _z =2000 a _p fv, and the empirical formula for the cutting force when machining cast iron is: F _z =1000 a _p fv. That is to say, when cutting steel, its cutting force is about 2000N, and when cutting cast iron, its cutting force is about 1000N. Compared with the above data, it is proved that the cutting force of the forming blade is feasible.

3 tool durability

The total cutting time of the tool from the start of the cutting to the wear level to the blunt standard is defined as the tool durability, expressed in T. It does not include non-cutting times such as measurement and tool setting. The higher the tool durability during the same amount of cutting and blunting, the slower the tool wears or the better tool cutting performance.
The relationship between tool durability and cutting capacity can be expressed by the extended Taylor formula, and the turning speed v is The coefficients and indices in the formula are available in Table 4. When the processing material is hard aluminum, the processing form is an outer longitudinal wheel, and the tool material is high speed steel, f≤0.20mm/r, C _v =388, x _v =0.12, y _v =0.25, m=0.28, substituting After the formula, vT ^0.28 = 363 was obtained.
According to the above relationship, the following table can be obtained (set: a _p = 50.11 mm, f = 0.20 mm/r).

Correspondence between durability and cutting speed in hard aluminum turning

Durability T (min)		500	1000	2372	4000	7915
Cutting speed v(m/min)	External longitudinal car	63.7	52.5	41.2	35.6	29.4
	Form turning	54.2	44.6	35.0	30.3	25.0

4 Selection of cutting amount

1. The amount of knife used for cutting a _p DS/1006 forming knives varies, and the amount of knives from small to large as the depth of the knife increases is up to 50.11 mm.
2. Feed amount f The main factor limiting the feed rate during roughing is the cutting force. The main factor limiting the feed rate during finishing is the surface roughness. When the DS/1006 forming knife is roughing, the amount of the knife is changed from small to large. To ensure that the cutting force is not too large, the feed rate is gradually reduced from 0.20 mm/r, and becomes smaller as small as 0.02 mm when finishing. r.
3. Cutting speed v When a _p and f are selected, the cutting speed v is selected on this basis. The cutting speed is limited by the durability of the tool, and the maximum cutting speed must be selected to ensure the reasonable durability of the tool. During the turning process, the coolant is kerosene. After the above cutting force and durability analysis plus years of processing experience, the final cutting amount is: in the whole process of processing, two cutting speeds are used to process. In the initial roughing process, the width of the knife is not large, the cutting speed is 35m/min, and the feed rate is 0.20~0.05mm/r. As the cutting width increases, the cutting force increases gradually. . When the cutting width reaches about 30 mm, the cutting speed is changed to 25 m/min, and the feed amount is 0.05 to 0.02 mm/r, which is gradually decreased. The parts processed by this method fully meet the technical requirements, and the production efficiency is increased by 10 times, which reduces the production cost.

5 Conclusion

In the tool design, the processing quality, durability and cost depend on whether the tool material selection is reasonable and correct. The structure of the DS/1006 comb-forming knife adopts a machine-clip split structure. It has better processing technology and better interchangeability than the circular forming knife. Tool geometry parameters: the front angle is 8° and the back angle is 10°. The forward and back angles are changed.
To accommodate the specific conditions of a knife width of 50.11 mm, the DS/1006 comb forming knife uses a varying feed rate and two lower convertible cutting speeds to complete a part process. At normal cutting times, the cutting force is between 1000 and 2000 N, which is usually within the range allowed by the cutting force of the tool.
The Taylor formula is an important calculation formula for durability. The durability of the DS/1006 comb-forming knife was calculated according to the extended Taylor formula: 2,372 min for roughing (v=35 m/min) and 7915 min for finishing (v=25 m/min). The correct amount of cutting is required to ensure the durability of the tool. According to the data, the durability of the tool can process about 1000 V30 door opener axles.
The DS/1006 comb forming knife ensures the processing quality of the V30 door opener axle, which makes the multi-wedge belt drive of the door opener smooth, low noise, large transmission power and long service life.

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