도구 모니터링용 측정 시스템

초고감도 압전(force) 센서를 스위스형 자동선반의 공구 홀더에 직접 통합하여, 절삭력이 가장 크게 작용하는 공구 절삭날 근처에서 가공 전 과정(황삭부터 마무리 가공까지)의 절삭력을 간접적으로 정밀·고해상도로 측정할 수 있습니다.

Kistler의 마이크로 가공 전용 솔루션은 Piezo Tool System (PTS linear)의 퀵체인지 시스템 ‘리니어 유닛(Linear Unit)’을 기반으로 하며, Paul Horn GmbH와의 협업으로 개발되었습니다. 센서는 기계 인터페이스와 베이스 플레이트 사이에 배치되어 있어, 빠른 공구 교환의 장점은 유지하면서 다양한 공구 홀더를 모니터링할 수 있습니다.

마이크로 가공에서 매우 작은 절삭력을 실시간으로 계측하면, 초고해상도 절삭력 데이터가 생성됩니다. 이를 통해 공정 중 발생하는 미세한 힘의 변동과 진동까지 포착할 수 있으며, 이는 공구 마모로 인한 공정 이상을 조기에 식별하는 중요한 지표가 됩니다. PTS를 통한 절삭력 측정은 사용자가 공구 마모나 파손으로 인한 손상 발생 전에 적시에 개입(예: 기계 정지) 할 수 있도록 지원합니다.

Kistler의 CNC 선반 및 다축 선반용 맞춤형 솔루션은 Paul Horn GmbH와 공동 개발한 Piezo Tool System (PTS) 공구 홀더를 기반으로 하며, 이 안에는 Kistler의 압전(force) 센서가 통합되어 있습니다. 회전 공구 시스템에서는 텔레메트릭 계측 시스템(TMS)이 회전하는 기계 요소로부터 신호를 전송합니다.

다양한 터닝(선삭) 응용에 적용 가능한 PTS 공구 홀더 시스템은 절삭력을 측정하고, 공구 마모로 인한 공정 편차를 나타내는 미세한 절삭력 변화를 감지할 수 있습니다. PTS의 실시간 절삭력 측정을 통해 가공 중에도 적시에 개입(예: 기계 정지)이 가능하여, 황삭부터 마무리 가공까지 공구 마모나 파손으로 인한 손상을 사전에 방지할 수 있습니다.

Changing tools during rough machining of workpieces on CNC machines with tool turrets is a rapid process involving high cutting forces. Tool wear is significant and increases the risk of tool breakage. Excessive cutting forces damage the material and can result in thermal deformations, cracks and rough surfaces, which can cause damage to tools and necessitate reworking. Once again, monitoring of cutting forces is the means of choice to check for rapid tool wear and prevent tool breakage. 

Cost-efficient solution from Kistler:

For this purpose, we integrate a piezoelectric force sensor directly under the bolt that secures the turret housing on the slide in order to measure the moment transferred to the bolt by the cutting forces. This system is especially suitable for rough machining processes, where the cutting forces are high enough to be transferred within the machine structure and measured relatively by the sensor. The precision of this kind of measurement is mainly dependent on the stiffness of the structure and the magnitude of the cutting forces. Thanks to the highly sensitive piezo technology, even the smallest changes in the process can be recorded.

Advantages of process monitoring and tool monitoring in CNC machining centers with tool turrets through the integration of piezoelectric force sensors:

• Reduction of tool costs thanks to optimized tool lifetimes 
• Less scrap and higher, more uniform quality of workpieces
• Minimization of machine downtime

One method for monitoring the tool status in single-purpose machines is the integration of piezoelectric strain sensors and force sensors into the machine structure. Cutting forces cause strain in the machine structure. Depending on the positioning and how the forces acting on the machining point are transferred to the machine structure, this strain can be monitored very well in relative terms via highly dynamic measurement using piezoelectric sensors. An increase in cutting forces results in greater strain in the structure of the machine. This, in turn, allows us to draw conclusions about the degree of tool wear or anomalies in the machining process. The system is easy to retrofit on existing systems. 

Advantages of machine monitoring and tool monitoring in single-purpose machines through the integration of strain and force sensors: 

• Extension of tool lifetimes 
• Minimization of machine downtime
• Machine stoppage in the case of process deviations
• Material batch comparison and monitoring
• Separation of potential scrap parts

When it comes to procuring a new machine tool for end customers, the ideal solution for monitoring the machining process and the tools themselves is often a fully integrated monitoring solution that requires no additional installation work and which displays measurement data directly in the machine control. Many machine tool manufacturers already offer corresponding solutions that tend to observe machining processes via active current monitoring of machine spindles. 

These kinds of systems are sufficient for a broad spectrum of applications. However, when it comes to workpieces with extremely small diameters and therefore the smallest force-measuring ranges, these solutions often reach their technological limits. As an expert development and technology partner, this is where we come in: with piezoelectric measurement solutions for machine tools – from early concept development to prototype testing all the way to market launch. 

Advantages of a collaboration to develop monitoring solutions in machine tools:

• Benefit from Kistler’s expertise and core competency in the field of piezoelectric measurement technology
• Draw on an extensive product range of generic sensors, load amplifiers and integration possibilities in machines

Collaborative development of innovative measurement solutions for integration into machine tools

Coverage of customer-specific requirements using Kistler’s entire generic measurement technology portfolio

Legend

1. Broad portfolio of sensors for different measurands

2. Components for signal transmission and machine integration

3. Industrial charge amplifiers and data acquisition systems

4. Data integration into the machine tool

Collaborative development of innovative measurement solutions for integration into machine tools

Coverage of customer-specific requirements using Kistler’s entire generic measurement technology portfolio

Legend:

1. Broad portfolio of sensors for different measurands 

2. Components for signal transmission and machine integration

3. Dedicated processs monitoring systems

4. Digital output signals to interact with the machine