Technical Information

A-1 Large-Sized Parts Machining Technologies Supporting Large-Sized Machine Products

A-1 Large-Sized Parts Machining Technologies Supporting Large-Sized Machine Products

Toshiba Machine is engaged in the machining of large cast parts varying in size and able to accommodate up to 4.5m in width × 15m in length and weight capacities up to 100 ton. Amongst some of the largest sized machining of parts whose length exceeds 5meter.We continue to excel with our advanced technologies and manufacturing procedures, which cover a broad range from the machining from blank to dimensionally precise machine parts. We are proud to introduce to you this very unique technology for the machining of high-precision and large-sized machine parts.

[Platform]
A. Professional manufacturing, assembling and measuring technologies
[Applications]
Ultra-large-sized machines such as machine tools and injection molding machines

[Technical Highlights]

  • Maximum machining ability of plano milling machine. Machining of mainly cast parts of up to 4.5m in width × 15m in length (weight 100t).
  • Multi-point centering (or alignment) method setup that can minimize distortion and torsion of large-sized parts.

1. Introduction

When machining the large-sized parts, some of the key points to the success of holding tight and accurate geometry tolerance is to minimize deflection caused by the part or equipments or directly attributed to heat generation that occurs during machining.

2. Large-sized parts machining technologies

2.1 Alignment

Fig. 1 Example of long part

Fig. 1 Example of long part

Among some of the large-sized parts of machine tools, we occasionally encounter challenging parts to machine that have profiles which are thin and long which can easily distort or twist and bend during machining.
Fig. 1 shows such a part and the question becomes "how do we minimize distortion and torsion caused by self weight?" This can become an obstacle and a challenge.

Fig. 2 Rhombus quadrilateral method

Fig. 2 Rhombus quadrilateral method

For example when aligning a part and applying the rhombus quadrilateral method (4 points balance) shown in Fig. 2 deflection by its free weight is natural. The arrows shown point to the directions in which torsion or "flexing" are irregular to prevent this from occurring. We use our special multi point alignment method.
Also thermal distortion caused by machining is also minimized upon completion of machining the finished surface displays line or no deflection.

2.2 Machining environment (temperature) and accuracies

Fig. 3 Change in straightness of long part (8m-long bed)

Fig. 3 Change in straightness of long part (8m-long bed)

When machining large-sized parts, the environment and conditions influence the accuracies of the parts. Several variables which are introduced are as follows the machine and parts material (physical feature, and profile, internal stress), work holding posture, setup, inserts, cutters tool holders, and of course heat temperature generated during machining, measurement, temperature control, etc. Amongst other critical factors are the environment and the vicinity of the machining operation most importantly (temperature control) If there was 1 degree-Celsius temperature difference between the top and bottom surfaces of the work-piece, the defelection of 0.02mm occurs over 4m long. Such a deflection is caused while the part is left unattended. If the part is machined under an environment in which the temperature fluctuates heavily, then you can expect distortion combined with other conditions to have a direct influence on the part. If the does occur or happens an even more difficult problem or issue can prevail, one that can cause accuracy deteriorates.

Fig. 4 Large-sized surface grinding machine and wind shield wall

Fig. 4 Large-sized surface grinding machine and wind shield wall

To get a grasp on these issues and in order to take necessary countermeasures, We need to take into consideration atmospheric conditions such as machine temperature, part temperature, and ambient temperature.Once we identify and control these variables before and after machining then high accuracy machining of a part is achieved.
An air-conditioned plant that is temperature controlled seasonal and consistently set to ±2°C and where parts are not exposed to direct air from the air conditioner. Fig. 3 shows the change in straightness of a slide way 8m long when exposed to air alone versus direct air from an air conditioner for one minute results are area1 straightness changed approx 5μm. As shown from this test, high accuracy machining is difficult to obtain when condition are not stable, to minimize this problem a wind shield wall as shown in Fig. 3 is installed around the machine. Around the machine that needs high accuracy machining, set windshields to minimize temperature change, and machining only after measure and confirm the effects. (Fig. 4)

3. Conclusion

Fig. 5 Floor type horizontal boring and milling machine (Ram movement 23m × table width 4.5m)

Fig. 5 Floor type horizontal boring and milling machine (Ram movement 23m × table width 4.5m)

Large-sized structures which include machine tools, injection molding machines, and die casting machines developed by Toshiba Machine are built by the large-sized machining facilities, Fig. 5, illustrates a floor type boring and milling machine. We have discussed some of the challenges & factors that influence the manufacturing and production of large-sized machines which described the following plant environment excellent machining technologies & techniques we at Toshiba Machine look forward to continually be your number one choice and will always strive to maintain our reputation and be your premier solution.